Mother checking daughter's temperature at home, unaware of asymptomatic contagion risks.

The Invisible Threat: Why We Can’t Rely on Symptoms to Detect Contagion

by Blog

The human body is remarkably deceptive when it comes to infectious diseases. We’ve been conditioned to think of illness in terms of visible symptoms: the telltale fever, the persistent cough, the runny nose that signals it’s time to stay home. But this symptom-centric view of contagion represents a dangerous blind spot in our understanding of how diseases spread—one that has significant implications for public health and workplace safety. 

The Myth of Symptomatic Contagion 

Most people operate under the assumption that contagious individuals are easily identifiable. They’re the ones calling in sick, reaching for tissues, or sporting that unmistakable look of someone fighting off an infection. This belief creates a false sense of security that has been repeatedly shattered by epidemiological evidence. 

The reality is far more complex and concerning. Many of the most common infectious diseases spread efficiently during periods when infected individuals feel perfectly fine and show no outward signs of illness. This phenomenon, known as asymptomatic or presymptomatic transmission, challenges our fundamental assumptions about contagion. 

Take influenza, for example. Research shows that people can shed infectious viral particles for 24-48 hours before symptoms appear, and some individuals remain contagious for days while experiencing no symptoms whatsoever. COVID-19 demonstrated this principle on a global scale, with studies indicating that asymptomatic individuals accounted for a significant portion of transmission events. 

The Fever Fallacy 

Perhaps no single symptom has been more relied upon as a screening tool than fever. Temperature checks became ubiquitous during the COVID-19 pandemic, creating an illusion of safety based on a fundamentally flawed premise. The assumption that fever serves as a reliable indicator of contagiousness has been thoroughly debunked by scientific evidence. 

Fever patterns vary dramatically across different pathogens and individuals. Some highly contagious diseases, including certain strains of norovirus and respiratory syncytial virus (RSV), frequently present without fever. Even in diseases where fever is common, it often appears after the peak contagious period has already begun. Moreover, individual immune responses vary so significantly that some people simply don’t develop fevers despite active infections. 

The reliance on fever screening has created what epidemiologists call a “screening paradox”—the most dangerous individuals from a transmission standpoint are often those who feel well enough to go about their daily activities, unknowingly spreading pathogens to others. 

The Contagion Technology Gap

In an era where we can detect trace amounts of explosives in airport security lines and identify specific allergens in food products, it’s striking that we lack commercially available technology to detect the presence of common pathogens in real-time. This technological blind spot represents one of the most significant challenges in modern infection control. 

Current pathogen detection methods are largely confined to laboratory settings, requiring specialized equipment, trained personnel, and processing times that make them impractical for routine screening. While rapid antigen tests have become more prevalent, they suffer from significant limitations: they’re pathogen-specific, often require symptoms to be present for accurate results, and can miss infections during early stages when individuals may be most contagious. 

The absence of portable, real-time pathogen sensors means we’re essentially flying blind when it comes to assessing the biological safety of shared spaces. We can measure air temperature, humidity, and chemical pollutants with consumer-grade devices, but we cannot detect the invisible clouds of respiratory droplets containing infectious agents that may be circulating around us. 

Several companies and research institutions are working on next-generation biosensor technology, including devices that could potentially detect viral or bacterial signatures in exhaled breath or environmental air samples. However, these technologies remain in development stages, facing challenges related to sensitivity, specificity, cost, and regulatory approval. 

Beyond Individual Responsibility 

The limitations of symptom-based screening and the absence of practical pathogen detection technology point to a fundamental shift needed in how we approach infection control. Rather than relying on individual self-assessment or basic screening measures, we must acknowledge that infectious agents may always be present in shared environments. 

This perspective isn’t about fear-mongering—it’s about realistic risk assessment based on scientific evidence. Just as we don’t wait to see smoke before installing fire suppression systems, we shouldn’t wait for visible symptoms before implementing measures to reduce pathogen transmission. 

The Contagion Mitigation Imperative 

The logical conclusion of this evidence-based analysis is clear: the only reliable way to protect occupants in any shared space is to assume that pathogens are always present and to implement mitigation strategies accordingly. 

This approach, sometimes called “universal precautions” in healthcare settings, involves creating layered defense systems that don’t depend on identifying infected individuals. These strategies include improved ventilation systems with proper air filtration, regular disinfection protocols, design modifications that reduce contact with shared surfaces, and when appropriate, personal protective equipment. 

The investment in continuous mitigation measures pays dividends beyond infectious disease prevention. Improved air quality benefits everyone, regardless of pathogen presence. Reduced surface contamination creates healthier environments for all occupants. These measures represent a shift from reactive to proactive health protection. 

In workplaces, schools, and public buildings, this means moving beyond policies that rely solely on sick individuals staying home. While personal responsibility remains important, it’s insufficient as a standalone strategy. Environmental controls, architectural modifications, and systematic approaches to air quality management become essential components of a comprehensive health protection strategy. 

The invisible nature of pathogen transmission demands visible, consistent action. In a world where we cannot reliably detect when threats are present, our only rational response is to act as if they always are. This isn’t paranoia—it’s preparedness based on scientific reality. 

Downtown Phoenix skyline with the ASHRAE 2025 Annual Conference logo overlayed.

ASHRAE 2025: The Future of Indoor Air Quality is Taking Shape

by Blog

A few weeks ago, I joined several thousand colleagues in Phoenix, Arizona for the ASHRAE 2025 Annual Conference, one of the two pivotal meetings where the organization conducts its most important business. This year’s conference felt particularly significant as we welcomed our new President, Bil McQuade, and his compelling theme for the 2025-26 ASHRAE Society Year: “Healthy Buildings: Designing for Life.”

As McQuade eloquently states on his Presidential Page, “Balancing energy efficiency with good IEQ ensures that buildings are not only environmentally sustainable but also conducive to the health and productivity of their occupants, creating a win-win situation for both people and the planet.” This philosophy perfectly captures where our industry is heading.

ASHRAE Standards in Motion: Progress Worth Celebrating

During the conference, I participated in numerous committee meetings—Guideline 42, SSPC 62.1, SSPC 241, EHC, SSPC 185.5, SSPC 145, and TG2.RAST among others. While my primary focus remains indoor air and environmental quality, including pathogen reduction on both air and surfaces, I was struck by a common thread running through every discussion: the urgent need to improve indoor spaces for occupant safety and health.

ASHRAE 2025: The Pathogen Standard is Coming

One of the most exciting developments is the progress of the 241 standard on controlling infectious aerosols. After completing its public review and comment period (a process that allows anyone to influence changes to existing and new standards), we’re expecting publication in spring 2026. This represents a major milestone—the first-time pathogens will be formally integrated into indoor air quality standards as an ANSI standard that can be adopted into building codes.

The response was overwhelming, with a high volume of comments indicating strong industry interest. While no standard is perfect, this continuous improvement approach allows us to evolve with new technologies and research findings.

Beyond Minimum: The Guideline 42 Opportunity

Here’s something every engineer and building owner should understand: standards like 62.1 represent minimum requirements. When you design a building to meet these standards, you’re providing the baseline level of protection from airborne contaminants—not optimal protection.

This is where Guideline 42 becomes invaluable. It provides practical guidance for creating facilities that exceed minimum requirements. Currently undergoing updates to reflect current best practices (potentially including pathogen considerations), this guideline represents the bridge between “code compliant” and “truly healthy” buildings.

Emerging Technologies: The Testing Revolution

The work happening in TG2.RAST (Technical Group on Reactive Air and Surface Technologies) demonstrates how seriously we’re taking next-generation IAQ solutions. Unlike traditional single-pass effectiveness tests designed for filters and UV technologies, new testing standards like 185.5 and 145.3 focus on duct-mounted technologies that actively work within occupied spaces.

Standard 185.5 recently completed its public comment period, and we’re optimistic about its upcoming publication. These developments signal a shift toward more comprehensive approaches to indoor air quality.

The Bigger Picture: Why This Matters

While technology adoption in our industry can feel glacially slow, the progress is real and accelerating. The collaborative efforts of manufacturers, engineers, technicians, academics, and scientists ensure that only proven, viable technologies gain widespread adoption.

We’ve long known that good filtration and fresh air are fundamental to indoor air quality. However, as I’ve discussed in previous posts, these solutions alone aren’t sufficient. The future lies in balanced systems that combine traditional approaches with modern active technologies—a comprehensive solution addressing all aspects of IAQ and IEQ.

Seeing ASHRAE embrace this holistic direction gives me tremendous optimism for our industry’s future.

ASHRAE 2025 Call To Action: Your Voice Matters

Whether you’re an engineer, building owner, scientist, academic, or simply someone passionate about the built environment, ASHRAE needs your perspective. The standards and guidelines shaping tomorrow’s buildings are developed through volunteer expertise and diverse viewpoints.

Ready to contribute to healthier buildings? Visit ASHRAE.org to learn more about membership and how you can make a difference.

The path to truly healthy buildings isn’t just about meeting minimum standards, it’s about reimagining what’s possible when we prioritize occupant health alongside energy efficiency. The work happening now will define the built environment for generations to come.

Ductwork layout with building plans illustrating ASHRAE ventilation design.

Beyond Fresh Air: Why ASHRAE’s Ventilation Standards Need Active Air Cleaning

by Blog

The COVID-19 pandemic fundamentally changed how we think about indoor air quality. Suddenly, terms like “air changes per hour” and “MERV ratings” entered everyday conversations. But as we’ve learned more about airborne pathogen transmission, a critical question has emerged: Is bringing in fresh outdoor air enough to keep us safe? Recent research suggests the answer is more nuanced than we might expect. While ASHRAE ventilation standards provide essential foundations for healthy buildings, they may not be sufficient on their own for rapid pathogen control—especially when every minute counts for infection prevention. 

The Gold Standard: ASHRAE Ventilation Rate Procedure 

ASHRAE has long been the authority on indoor air quality standards. Their Standard 62.1, particularly the Ventilation Rate Procedure (VRP), serves as the backbone for ventilation design in buildings across North America. 

What Makes the VRP Valuable 

The VRP isn’t just about pumping in outdoor air—it’s a comprehensive system that addresses multiple aspects of indoor air quality: 

  • Tailored Ventilation Rates: Rather than a one-size-fits-all approach, the VRP prescribes specific outdoor air rates based on space type and occupancy. A computer lab has different requirements than a science laboratory or office space, reflecting the unique contamination sources and occupancy patterns of each environment. 
  • Holistic System Design: The standard goes far beyond ventilation rates, covering everything from building envelope design to prevent moisture problems, proper filter specifications (MERV-8 or higher), and strategic placement of outdoor air intakes to avoid contamination sources. 
  • Smart Air Management: Perhaps most importantly, the standard classifies indoor air into four categories based on contamination levels, with strict rules about where that air can be recirculated. This prevents contaminated air from spreading throughout a building. 
  • Continuous Evolution: ASHRAE standards are living documents, regularly updated based on the latest research and real-world performance data. 

The Fresh Air Limitation: New Research Reveals Critical Gaps 

While the VRP provides excellent general indoor air quality, recent research by ASHRAE members Brett Duffy and Dr. Margaret Scarlett has revealed a significant limitation when it comes to rapid pathogen control. 

Their study compared traditional ASHRAE ventilation methods against continuous active in-room air cleaning devices (CA-IRAC) using bacteriophage MS2—a surrogate for dangerous pathogens like SARS-CoV-2 and influenza viruses. 

The 4-Minute Problem 

The results were striking. In the critical first four minutes of exposure: 

  • Active air cleaning: 70% pathogen reduction 
  • ASHRAE 62.1 ventilation: Just 1.5% reduction 
  • Enhanced ventilation (Standards 170 & 241): 32-50% reduction 

Why does this matter? Because respiratory infections can occur within minutes of exposure to infectious particles. By the time traditional ventilation achieves significant pathogen reduction, exposure may have already occurred. 

Dilution vs. Elimination: A Fundamental Difference 

The research highlights a crucial distinction: outdoor air ventilation dilutes pathogens by mixing contaminated indoor air with clean outdoor air and exhausting the mixture. Active air cleaning devices eliminate pathogens by destroying them within the space. 

Think of it this way: dilution is like adding clean water to muddy water—you reduce the concentration, but the mud particles are still there. Elimination is like filtering out the mud entirely. 

The Path Forward: Complementary Strategies to ASHRAE Ventilation

This doesn’t mean we should abandon fresh air ventilation—quite the opposite. The research suggests that the most effective approach combines both strategies: 

Why We Still Need Fresh Air 

Outdoor air ventilation remains essential for: 

  • Removing carbon dioxide and body odors 
  • Controlling humidity levels 
  • Diluting chemical contaminants from building materials and furnishings 
  • Providing the psychological benefits of fresh air 
Where Active Air Cleaning Excels 

Continuous active air cleaning devices provide: 

  • Rapid pathogen reduction when it matters most 
  • Consistent performance regardless of outdoor air quality 
  • Energy efficiency compared to heated/cooled outdoor air 
  • Protection against both known and unknown airborne threats 

Practical Implications for Building Operators 

For facility managers and building operators, this research suggests several actionable steps: 

Immediate Actions: 
  • Assess current ventilation performance against ASHRAE standards 
  • Consider portable or installed active air cleaning devices for high-risk spaces 
  • Ensure existing ventilation systems are properly maintained and commissioned 
Long-term Planning: 
  • Design new systems with both adequate ventilation and active air cleaning 
  • Monitor emerging ASHRAE guidance on integrated approaches 
  • Consider spaces with high transmission risk (meeting rooms, cafeterias, classrooms) as priorities for enhanced air cleaning 

Looking Ahead: The Future of Indoor Air Quality 

The pandemic taught us that indoor air quality isn’t just about comfort—it’s about health and safety. As ASHRAE continues to evolve its standards based on emerging research, we can expect to see greater integration of active air cleaning technologies alongside traditional ventilation approaches. 

The goal isn’t to choose between fresh air and air cleaning—it’s to use both strategically. Fresh air provides the foundation for healthy indoor environments, while active air cleaning provides the rapid response needed for pathogen control. 

In our interconnected world, where people spend up to 90% of their time indoors, this dual approach may well become the new standard for truly safe and healthy buildings. 

 

This analysis is based on research by ASHRAE members Brett Duffy and Dr. Margaret Scarlett, published in peer-reviewed studies on ventilation effectiveness and pathogen control. Building operators should consult with qualified HVAC professionals when implementing changes to ventilation or air cleaning systems. 

Engineers reviewing building design plans to ensure compliance with ASHRAE Standards for indoor air quality and safety.

Bridging the Gap: How ASHRAE Standards Lead Building Codes and the Case for Early Adoption

by Blog

The relationship between ASHRAE standards and building codes represents one of the most significant dynamics in modern construction and building performance. While building codes establish the minimum legal requirements for construction, ASHRAE standards often serve as the technical foundation that eventually shapes these codes. However, a critical lag time exists between when ASHRAE publishes updated standards and when these improvements are incorporated into enforceable building codes—creating both challenges and opportunities for forward-thinking building owners and designers. 

The Standards-to-Code Pipeline: Understanding the Lag 

ASHRAE continuously develops and updates technical standards based on the latest research, technology advances, and lessons learned from field experience. These standards undergo rigorous peer review and public comment periods before publication. However, the journey from ASHRAE standard to enforceable building code follows a complex path that can span several years. 

The process typically unfolds in stages: ASHRAE publishes or updates a standard, which then must be reviewed by code development bodies such as the International Code Council (ICC). These organizations evaluate the standard for incorporation into model codes like the International Building Code (IBC) or International Energy Conservation Code (IECC). Even after inclusion in model codes, individual jurisdictions must adopt these updated codes—a process that varies significantly by location and can add additional years to implementation. 

This lag time means that newly constructed buildings designed to meet only current code requirements may already be using outdated technical approaches by the time they’re completed. The disconnect becomes more pronounced in rapidly evolving areas like energy efficiency, indoor air quality, and building resilience. 

ASHRAE Standards Early Adoption Advantage: Extending Facility Useful Life 

Building owners and designers who choose to implement current ASHRAE standards ahead of code requirements position themselves for significant long-term advantages. Early adoption serves as a form of future-proofing that can substantially extend a facility’s useful life and market relevance. 

When buildings incorporate advanced standards before they become mandatory, they avoid the costly retrofits that competitors may face when codes eventually catch up. This proactive approach also positions buildings to meet evolving tenant expectations, regulatory requirements, and market demands. Properties designed with forward-looking standards often command higher rents, attract quality tenants more easily, and maintain their value longer in competitive markets. 

Early adoption also provides operational benefits. Buildings designed to exceed current codes typically demonstrate superior energy performance, resulting in lower operating costs throughout their lifecycle. Enhanced indoor air quality and comfort features improve occupant satisfaction and productivity, creating value that extends far beyond initial construction costs. 

ASHRAE 62.1: The Ventilation Standard That Shapes Indoor Air Quality 

ASHRAE Standard 62.1, “Ventilation for Acceptable Indoor Air Quality,” exemplifies how standards evolve to address emerging health and performance concerns. This standard has undergone numerous updates to incorporate new understanding about ventilation effectiveness, contaminant control, and the relationship between indoor air quality and occupant health. 

The standard’s evolution reflects growing awareness of indoor air quality’s impact on productivity, health outcomes, and overall building performance. Recent updates have addressed issues like demand-controlled ventilation, natural ventilation credits, and enhanced filtration requirements—improvements that often don’t appear in building codes until years after ASHRAE publication. 

Buildings designed to current 62.1 requirements rather than older code-mandated versions typically provide superior indoor environments that support occupant wellbeing and organizational productivity. This translates to reduced sick leave, improved cognitive performance, and enhanced overall satisfaction among building users. 

ASHRAE 241: The Game-Changer for Infection Control 

ASHRAE Standard 241, “Control of Infectious Aerosols,” represents a paradigm shift in how buildings address airborne disease transmission. Developed in response to lessons learned during the COVID-19 pandemic, this standard provides comprehensive guidance for reducing infection risk through building design and operation. 

Standard 241 addresses ventilation, filtration, air cleaning, and other strategies for controlling infectious aerosols in buildings. It establishes equivalent clean airflow rates and provides frameworks for assessing and improving infection control in various building types and spaces. 

If applied to all new construction, Standard 241 would create buildings significantly more resilient to airborne disease transmission than those meeting only current building code requirements. The standard addresses gaps in traditional codes that focus primarily on comfort and basic air quality rather than specific infection control measures. 

Early adoption of Standard 241 principles offers building owners a competitive advantage in attracting tenants who prioritize health and safety. In a post-pandemic world, buildings that can demonstrate superior infection control capabilities often command premium rents and experience lower vacancy rates. The standard also positions buildings to adapt more easily to future health crises or evolving public health requirements. 

ASHRAE Standards Strategic Implementation: Making the Case for Excellence 

The decision to exceed current code requirements requires balancing additional upfront costs against long-term benefits. However, the most successful projects often find that implementing advanced ASHRAE standards during initial design phases adds minimal cost compared to retrofitting later. 

Design teams can leverage current standards to create buildings that remain relevant and valuable for decades rather than becoming obsolete as codes evolve. This approach requires collaboration between owners, designers, and contractors to identify which standards offer the greatest long-term value for specific project types and markets. 

The key lies in viewing ASHRAE standards not as optional enhancements but as insights into the future of building performance requirements. By implementing these standards before they become mandatory, building owners and designers create facilities that lead rather than follow market expectations. 

Conclusion: ASHRAE Standards Leading the Future of Building Performance 

The lag between ASHRAE standard updates and building code implementation creates opportunities for forward-thinking building owners and designers to create superior facilities that maintain their value and relevance longer. Standards like 62.1 and 241 demonstrate how technical excellence can translate into operational advantages, occupant satisfaction, and market competitiveness. 

Rather than viewing current building codes as targets to meet, successful projects increasingly treat them as minimum starting points while using current ASHRAE standards as guides to excellence. This approach creates buildings that serve occupants better, operate more efficiently, and adapt more readily to evolving requirements and expectations. 

The question for building owners and designers isn’t whether to exceed current codes, but rather which standards offer the greatest value for creating facilities that will thrive throughout their intended lifespans. In an era of rapid technological advancement and evolving understanding of building performance, early adoption of ASHRAE standards represents sound risk management and strategic positioning for long-term success. 

Gloved hand holding petri dish used to study microbes for understanding the pathogen elimination hierarchy in disinfection.

Understanding Pathogen Elimination: A Hierarchy of Resistance

by Blog

Effective pathogen elimination and control is critical in healthcare settings, food safety, and water treatment. As the lab results demonstrate, different microorganisms exhibit varying levels of resistance to disinfection methods. This resistance hierarchy has important implications for infection prevention strategies. 

The Pathogen Elimination Hierarchy 

The test results reveal a clear progression from “easiest to kill” to “hardest to kill” pathogens: 

  1. Enveloped Viruses (Easiest to Kill) 
    • Enveloped viruses like SARS-CoV-2 (coronavirus) and H1N1 influenza have a lipid membrane that’s vulnerable to disruption. These pathogens are relatively fragile and typically respond well to most disinfection methods. Importantly, enveloped viruses are often much more contagious than their non-enveloped counterparts, which is part of what makes them particularly dangerous in community settings. Their higher transmissibility means they can spread rapidly through populations despite being relatively easy to eliminate with proper disinfection. 
  2. Bacteria (Moderate Difficulty) 
    • Moving up the difficulty scale, bacteria require more robust disinfection approaches. This category includes common pathogens such as MRSA (Staph infections), Escherichia coli, Listeria, Pseudomonas (Pneumonia), and Enterococcus faecalis. 
  3. Fungi (Higher Difficulty) 
    • Fungi present greater challenges due to their cell walls and adaptive capabilities. Examples shown in the results include Candida Auris and Trichophyton interdigitale (Tinea Pedis or athlete’s foot). 
  4. Non-enveloped Viruses (Very Difficult) 
    • These viruses lack the lipid envelope that makes their enveloped counterparts vulnerable. They show significant resilience to many disinfection methods. This category includes MS2 Bacteriophage (commonly used as a coronavirus surrogate) and Feline calicivirus. Non-enveloped viruses are generally less contagious than enveloped viruses, which makes them safer to work with in laboratory settings. Their reduced transmissibility, combined with their greater resistance to disinfection, makes them ideal candidates for surrogate testing. 
  5. Bacterial Spores (Hardest to Kill) 
    • At the far end of the spectrum, bacterial spores like Clostridium difficile (C. difficile) represent the ultimate challenge for disinfection technologies. 

The Cascading Effectiveness Principle 

A fundamental concept in disinfection strategy is the “cascading effectiveness principle”: if your disinfection method can effectively eliminate pathogens higher on the difficulty scale, it will generally be even more effective against those lower on the scale. 

This is why the ASHRAE 241 standard uses MS2 bacteriophage as a surrogate organism for testing. As a non-enveloped virus, MS2 is significantly more resistant to disinfection than many common pathogens like coronaviruses. When a disinfection system demonstrates effectiveness against MS2, you can be confident it will perform well against less resistant organisms. 

Practical Implications 

Understanding this hierarchy offers several advantages: 

  • Strategic Disinfection Planning: Target your approaches to address the most resistant organisms relevant to your environment. 
  • Cost-Effective Solutions: By knowing which pathogens pose the greatest challenge, resources can be allocated efficiently. 
  • Validation Methods: Using resistant organisms like MS2 bacteriophage as testing surrogates provides confidence in disinfection system performance. 
  • Comprehensive Protection: A system proven effective against non-enveloped viruses or bacterial spores will likely provide robust protection against the full spectrum of microbial threats. 

Pathogen Elimination Hierarchy

By understanding this hierarchy, infection control professionals can implement more effective strategies that account for the full spectrum of microbial threats. 

For facilities implementing disinfection technologies, this cascading effectiveness principle offers reassurance: a system validated against highly resistant organisms like MS2 bacteriophage or C. difficile spores will almost certainly provide exceptional protection against less resilient pathogens. 

This science-based approach to pathogen control ensures more comprehensive protection and better outcomes in healthcare environments, food processing facilities, and other settings where infection prevention is critical. 

Diagram illustrating the Hierarchy of Controls: Elimination, Substitution, Engineering Controls, Administrative Controls, and Personal Protective Equipment (PPE).

The Hierarchy of Controls: A Systematic Approach to Pathogen Management

by Blog

When it comes to protecting people from pathogens and other workplace hazards, not all control measures are created equal. The Hierarchy of Controls is a systematic approach that prioritizes the most effective strategies for preventing exposure to hazards, including infectious agents. 

What is the Hierarchy of Controls? 

The Hierarchy of Controls is a framework used by safety professionals to implement effective control solutions. Developed by the National Institute for Occupational Safety and Health (NIOSH), this approach organizes hazard control strategies from most to least effective: 

  1. Elimination – Physically remove the hazard 
  2. Substitution – Replace the hazard 
  3. Engineering Controls – Isolate people from the hazard 
  4. Administrative Controls – Change the way people work 
  5. Personal Protective Equipment (PPE) – Protect the worker with PPE 

Most Effective: Elimination and Substitution 

At the top of the hierarchy are the most effective control measures: 

  • Elimination involves completely removing the hazard from the workplace. For pathogens, this might mean identifying and removing infected individuals from the environment or eliminating conditions that allow pathogens to survive. 
  • Substitution replaces a hazard with a less dangerous alternative. While challenging to apply directly to pathogens, it might involve replacing high-risk procedures with safer alternatives that achieve the same outcome. 

Engineering Controls 

Engineering controls are physical changes to the workplace that isolate people from hazards. These are particularly valuable for pathogen control and include: 

  • Advanced Disinfection Technologies 
  • Negative pressure rooms for airborne pathogens 
  • High-efficiency air filtration systems 
  • Physical barriers like sneeze guards 
  • Proper ventilation to reduce airborne transmission 

Administrative Controls 

Administrative controls change the way people work to reduce exposure: 

  • Developing policies for sick leave and remote work 
  • Implementing hygiene protocols 
  • Creating cleaning and disinfection schedules 
  • Training employees on infection prevention 
  • Adjusting work schedules to reduce crowding 

Least Effective: Personal Protective Equipment 

At the bottom of the hierarchy is PPE, which includes: 

  • Respirators and face masks 
  • Gloves 
  • Face shields 
  • Gowns and protective clothing 

While essential, PPE is considered the last line of defense because it relies on proper use by individuals and doesn’t eliminate the hazard at its source. 

Why The Hierarchy of Controls Works 

The Hierarchy of Controls provides a structured method for addressing pathogen risks. By focusing on elimination and engineering controls first, organizations can implement more reliable protections before resorting to measures that depend on individual compliance. 

For effective pathogen management, the best approach usually combines multiple controls across different levels of the hierarchy, creating layers of protection against infectious disease transmission. 

To learn more, check out the information at the source – The CDC.

Crowded indoor space with ASHRAE logo, representing efforts toward better indoor air quality.

Breathe Easy: ASHRAE’s Guidelines for Better Indoor Air

by Blog

Ever wonder what makes the air inside buildings healthy to breathe? ASHRAE publishes standards and guidelines for indoor air quality. Here’s what you need to know in plain language. 

What Are These Guidelines? 

Think of ASHRAE Standard 62.1-2022 as a rulebook for good indoor air in commercial facilities. It sets minimum requirements for ventilation (bringing fresh air in) and other measures to keep indoor air healthy for people. The goal is simple: make sure the air we breathe indoors won’t make us sick. 

Who Do These Guidelines Affect? 

These guidelines apply to most buildings where people spend time, except for residential homes. They’re used when: 

  • Building new structures 
  • Adding to existing buildings 
  • Making certain changes to buildings 
  • Improving air quality in older buildings 

Better Indoor Air: The Main Points Made Simple

Fresh Air Systems 

The guidelines explain how to design, install, and maintain systems that bring fresh air inside and clean the air that’s already there. 

Indoor Air Pollutants 

The rules address things that can make indoor air unhealthy, including: 

  • Outdoor pollution coming inside 
  • Dust and chemicals from construction 
  • Moisture and mold 
  • Cigarette smoke 

Outdoor Air Quality 

Before designing a ventilation system, builders need to check if the outdoor air in the area is clean enough. If it’s not, they must add filters or air cleaners to remove particles and harmful gases. 

Equipment Requirements 

The guidelines have specific rules for air system parts like: 

  • Where outdoor air enters the building (keeping these intakes away from exhaust fans, garbage areas, and other sources of pollution) 
  • Surfaces that the air flows over (making sure they resist mold) 
  • Drain pans (ensuring they don’t become breeding grounds for bacteria) 
  • Humidifiers (devices that add moisture to the air) 

There’s also emphasis on preventing Legionnaires’ disease, a serious type of pneumonia that can spread through water systems. 

Air Classification 

Not all indoor air is equal. The guidelines sort air into four classes based on how contaminated it might be and set rules for when this air can be reused or moved to other areas. 

Determining How Much Fresh Air Is Needed 

Designers can use several methods to figure this out: 

  • A straightforward approach based on room type and size 
  • A more complex method analyzing specific pollutants 
  • Guidelines for systems using natural airflow (like windows) 

Keeping It Clean 

The rules emphasize keeping air ducts clean during construction and making sure fresh air dampers (valves that control airflow) work properly before people move in. 

Ongoing Maintenance 

Regular upkeep of ventilation systems is required to ensure they continue working effectively. 

Checking Results 

For projects using the more complex design method, testing is required after completion to verify the air is actually clean. 

ASHRAE: Your Resource for Better Indoor Air 

These guidelines are constantly being updated as new research emerges. While following them isn’t legally required (unless local building codes say so), they’re widely recognized as the gold standard for healthy indoor air. By understanding these basics, you can better appreciate the behind-the-scenes work that goes into making the air in your workplace, school, or public buildings safe to breathe. To fully understand the standard, you can access a readable version of the entire document by visiting ASHRAE’s Technical Resources. 

 

AHR 2025 logo sign at the entrance of the Orlando conference, welcoming attendees from the HVAC industry.

CASPR Technologies at AHR 2025: Elevating Indoor Air Quality in the HVAC Industry

by Blog
AHR 2025 logo sign at the entrance of the Orlando conference, welcoming attendees from the HVAC industry.
ASHRAE logo displayed at AHR 2025 conference, highlighting the organization’s leadership in HVAC and indoor air quality standards.

The AHR 2025 conference in Orlando was an unparalleled experience for CASPR Technologies, bringing together industry leaders, innovators, and professionals from across the HVAC sector. The event served as the perfect platform for us to connect with experts, exchange ideas, and demonstrate how CASPR’s advanced technology is setting new standards for Indoor Air Quality (IAQ). Conversations throughout the event reaffirmed what we already knew—IAQ is no longer an afterthought. It has become a fundamental pillar of HVAC system design, implementation, and maintenance. As regulatory standards continue to evolve and awareness grows, HVAC professionals are seeking proven, data-driven solutions that ensure both safety and efficiency in every environment. Our team at CASPR Technologies was proud to be at the forefront of these discussions, driving innovation and education within the industry.  


The HVAC Industry is Bigger Than Ever 

AHR 2025 was a testament to the rapid growth and innovation happening within the HVAC industry. Walking the show floor, we were immersed in an environment that showcased the scale, diversity, and impact of the industry’s evolution. With thousands of exhibitors and attendees, it was clear that HVAC is a driving force behind healthier, more efficient indoor environments. The range of technologies on display—from cutting-edge filtration systems to AI-driven building automation—reinforced how IAQ is now woven into the very fabric of HVAC innovation. Whether in large-scale commercial applications, residential solutions, or specialized healthcare settings, there is an increasing demand for smarter, more effective air quality solutions. CASPR Technologies’ role in this landscape was undeniable, as we demonstrated how our continuous disinfection technology is revolutionizing the way air and surfaces are treated for safety and cleanliness. 


Indoor Air Quality Takes Center Stage 

One of the most notable shifts at AHR 2025 was the undeniable mainstream focus on IAQ. In past years, IAQ was often viewed as an added benefit—something to consider after primary HVAC functionalities were addressed. This year, however, it was front and center in every conversation. Whether discussing air purification, improved filtration, or next-generation pathogen treatment, professionals across the board recognized that effective IAQ solutions are essential for occupant health and safety. 

Moreover, we had the opportunity to engage with engineers, facility managers, and industry decision-makers who were all eager to learn how they could integrate validated, long-term IAQ solutions into their existing systems. Our team emphasized the importance of maintaining both air and surface cleanliness, as pathogen mitigation strategies must go beyond traditional approaches to create truly safe indoor environments. As regulatory bodies continue to set stricter standards for indoor air quality, it’s clear that data-backed, continuously active solutions like CASPR’s are becoming a necessity rather than an option. 

CASPR Technologies at AHR 2025 Takeaways: The Growing Importance of Pathogen Treatment 

At AHR 2025, pathogen treatment emerged as one of the most pressing topics in IAQ discussions, highlighting a growing industry-wide realization: true disinfection goes beyond air filtration—it must also address surface contamination. While traditional HVAC solutions have focused primarily on airborne pollutants, there is now an increasing demand for comprehensive, real-time mitigation strategies that tackle both airborne and surface-borne pathogens. 

As awareness grows around the role of pathogens in indoor environments, industry professionals are actively seeking proven solutions that don’t just capture contaminants but actively neutralize them. CASPR Technologies’ continuous disinfection technology captured the attention of engineers, facility managers, and HVAC specialists alike, who recognize that passive filtration alone is no longer enough. The ability to provide ongoing, automated pathogen reduction—without the use of chemicals or manual intervention—is becoming a critical requirement for modern IAQ strategies. 

Pathogen mitigation is no longer a reactive measure—it’s a proactive necessity. Schools, hospitals, commercial buildings, and residential spaces alike are prioritizing IAQ solutions that offer real-time, continuous protection against bacteria, viruses, and mold. Professionals expressed a strong desire for technologies that are not only validated by scientific data but also seamlessly integrate into existing HVAC systems without requiring costly modifications or downtime. 

The consensus was clear: effective, real-time pathogen mitigation is no longer just a competitive advantage—it’s an essential component of any serious IAQ strategy. As regulations tighten and industry standards evolve, there is a heightened expectation for continuous, scientifically backed solutions that can proactively reduce pathogens in the air and on surfaces. 

ASHRAE 241 and the Need for More Data 

A crucial industry discussion at AHR 2025 centered around ASHRAE 241, a new standard designed to provide guidelines for pathogen mitigation in indoor environments. While there is a growing push for IAQ advancements, one major challenge remains—the lack of published data for many existing technologies. Industry leaders stressed the importance of transparency in testing, safety validation, and efficacy reporting to ensure that businesses and consumers can make informed decisions about the technologies they implement. 

“I was surprised to find out how little people knew about IAQ standards and how a lot of the industry has no testing,” stated CASPR Representative Roberto Bonilla. 

CASPR Technologies has long been committed to setting the benchmark for industry standards. As part of our mission to deliver scientifically validated solutions, CASPR was the first technology to be tested for both safety and efficiency under ASHRAE 241 standards. This commitment to data-driven innovation positions CASPR Technologies as a trusted leader in the IAQ space, providing stakeholders with real, measurable results that demonstrate the true impact of our technology. 

CASPR Technologies at AHR 2025: A Packed Room and Engaging Conversations 

One of the highlights for CASPR Technologies at AHR 2025 was the overwhelming turnout for our paper presentation, ‘Assessing Indoor Air Quality in a Comparative Study Among ASHRAE Ventilation Standards Compared to a Control with a Continuous Active In-Room Air Cleaning Device.’  With over 120 industry professionals in attendance, the room was filled with engineers, facility managers, and HVAC experts eager to dive deeper into IAQ advancements. 

The level of engagement and thoughtful questions from attendees reinforced that IAQ is no longer an afterthought—it’s a critical priority for the industry. Throughout the presentation, we discussed the importance of data-driven decision-making in IAQ solutions and how continuous active air cleaning devices can complement ASHRAE ventilation standards. The discussions that followed were not only insightful but also highlighted the growing demand for validated, real-world data on the effectiveness of air purification technologies. 

Many professionals expressed keen interest in how CASPR’s continuous disinfection solutions could be integrated into their existing HVAC systems to enhance air quality and pathogen mitigation. The enthusiasm and dialogue that emerged from this session demonstrated the need for transparent testing, standardized guidelines, and proven results in IAQ technology—something CASPR is committed to delivering. 

AHR 2025 provided the perfect platform to engage with industry leaders and share groundbreaking research, and we’re excited to continue these conversations as we push the boundaries of IAQ innovation. 

Innovation at Every Level 

Innovation in HVAC isn’t just about upgrading large-scale systems—it’s about refining and enhancing every individual component to create a more efficient and effective IAQ strategy. From advanced sensors that monitor air quality in real time to next-generation filtration technologies that capture even the smallest particulates, the industry is experiencing a wave of breakthroughs designed to optimize air circulation, purification, and disinfection. Engineers and manufacturers are focusing on smarter, more adaptable solutions that integrate seamlessly into both new and existing HVAC infrastructures, making high-quality indoor air more accessible than ever before. These advancements are not just about compliance with evolving standards—they are about fundamentally reshaping how we think about air quality in homes, offices, hospitals, and public spaces. 

At CASPR Technologies, we are thrilled to be part of this movement, pioneering continuous disinfection technology that works in tandem with HVAC systems to ensure that indoor environments remain as safe and healthy as possible. Unlike traditional air treatment methods that rely on passive filtration alone, our technology actively neutralizes pathogens in the air and on surfaces, providing a comprehensive approach to IAQ improvement. Whether it’s for schools, healthcare facilities, commercial spaces, or residential buildings, our goal is to make clean, purified air the standard, not the exception. By pushing the boundaries of what’s possible in HVAC and IAQ innovation, CASPR Technologies is committed to shaping the future of indoor air quality—one breakthrough at a time. 

 

CASPR Technologies AHR 2025: A Successful Event with a Bright Future 

Reflecting on our experience at AHR 2025, one thing is clear—the future of IAQ has never been stronger. The sheer level of interest, engagement, and collaboration we witnessed at the event speaks to the growing demand for innovative air quality solutions. The industry is evolving rapidly, and businesses are prioritizing health-focused, sustainable technologies more than ever before. 

For CASPR Technologies, this event was more than just an opportunity to showcase our technology—it was a chance to be part of an industry-wide movement towards better, safer indoor environments. The connections we made, the conversations we had, and the enthusiasm we witnessed all point to an exciting future for IAQ innovation. 

To everyone who stopped by our booth, attended our presentation, and engaged with us in meaningful discussions—thank you. Your passion and curiosity inspire us to continue pushing the boundaries of what’s possible in IAQ and HVAC technology. We look forward to the future, knowing that together, we can redefine indoor air quality and make every indoor space a safer place to live and work. 

 

CDC, HTTPS://WWW.CDC.GOV/ONE-HEALTH/ABOUT/INDEX.HTML

CASPR: A One Health Approach to Fighting Pathogens

by Blog

CASPR, a One Health approach to combat any emerging pathogens indoors

In the US, One Health is an interdisciplinary approach to health usually focused in local and state public health departments, that encompasses a broad array of sectors, including public health, agriculture, animal and meat production, and environmental experts.  The goal is to improve and encourage practices to improve health outcomes and reduce the threat of new, unknown pathogens, while containing exposure to the known pathogens. (1) CASPR technologies offers a comprehensive approach to improving health in our connected world by making indoor air safer, preventing spread of any new pathogen that emerges, as well as existing pathogens.  Simply, CASPR is a prevention component for indoor buildings and facilities through a One Health lens.

We know that antibiotics are highly effective, with an estimated 5.7 million people (about twice the population of Arkansas) dying annually from treatable infections because effective antibiotics are not available to them.  The problem is that antibiotics are overused, when they are improperly or inappropriately prescribed, and create antimicrobial resistance (AMR), in which antibiotics are not effective.  About a quarter of all antibiotic prescriptions in the US are unnecessary.  In addition, taking antibiotics for only a few days, or taking lower quality or the wrong antibiotics can have serious health consequences for the person and can create a path for drug-resistant organisms.

Outside of the US, lack of access to any antibiotic is a bigger problem in producing AMR.  AMR is a global hitchhiker that does not recognize the borders of human, animal, and plant vulnerability.  The astronomical cost of developing new antibiotics to keep pace with new mutations created with AMR is estimated to be about $1 billion (about $3.1 per person in the US) to develop 10 to 15 years to get through proper safety and efficacy testing to be marketed.  Everyone is at risk from AMR, so preventing AMR by reducing indoor pathogens with a continuously active indoor room air cleaner is the best prevention from spreading pathogens indoors, known, and unknown.

In particular, improper use of antibiotics for humans that are given to animals accounts for AMR. It should be noted that more than 70% of new infectious diseases are zoonotic—that is a pathogen “jumps” from animals to humans, sometimes after mutations.  Currently, many are keeping up to date on the latest news regarding Avian Flu (H5N1).  Avian Flu has been recently detected in pigs, who happen to be closer to human genetics capable of spreading new respiratory pathogens than cattle or poultry.  It is crucial to watch this in the coming weeks. 

Without proper facility air and surface controls in animal and meat products, animal products can become contaminated and can spread resistant bacteria by food contamination.  This can occur either by improper processing or cooking of animal products, or from fertilizer spraying of agricultural crops containing animal or human manure with resistant pathogens.  While some producers still use human antibiotics in animals to promote growth, or in feed, these practices can result in the production of resistant organisms, and results in AMR.  Therefore, AMR efforts within One Health should include livestock workers, farmers, and veterinarians, and a re-examination of pathogen reduction in air and surfaces, beyond intermittent surface cleaning or two-week fallow periods.

Evidence exists that antibiotic stewardship—a crucial One Health effort that ensures antimicrobials are used appropriately, only when necessary— reduces antibiotic consumption, slows drug resistance, and can be done without sacrificing patient and animal care.  In a multicountry study, a 7-day course of antibiotics to humans can be equally effective against bloodstream infections as a 14-day regimen, and less likely to create resistant organisms. (2)

Reduction of risk from respiratory pathogens indoors is another key goal of One Health. Respiratory pathogens, like avian flu, seasonal influenza, colds, and Respiratory Syncytial Virus (RSV) are spread through the air. Measles is particularly efficient at spreading indoors, with a 90% risk of transmission to unvaccinated individuals.

While we all want to forget the years of confusion about the COVID-19 pandemic, some key lessons can be learned from the height of the pandemic.  Infectious respiratory particles (IRPs) spread infection quickly from human to human, after “jumping” species from animals to humans.  Now, COVID-19 is still with us, mutating, and is still circulating, with its newest variants.  We are getting ready to hit prime seasonal influenza season, with a looming watch on avian flu, and other respiratory pathogens, like RSV, Simply, the COVID-19 pandemic taught us we need to be prepared and prevent infections indoors.  

So how do you prepare and prevent infections indoors?  We do not know who may be infected with pathogens inside the buildings where we work, play and live.  People could be recently infected but asymptomatic, releasing IRPS continuously, and needing a continuous cleaning process to match the continuous release of those pathogens.  A crucial One Health effort for antimicrobial stewardship promotes the appropriate use of antibiotics to humans, only when necessary, and this slows drug resistance, while assuring healthy outcomes of patients.  Preventing spread indoors with CASPR prevents the spread of AMRs, too, consistent with One Health concepts.

AMR is an important One Health effort because of the global burden of antimicrobial resistance, now and in the future.  In 2021, 4.71 global deaths were attributed to drug-resistant bacterial pathogens, directly responsible for 1.14 million deaths. (2, See also FIGURE 1, Reference 3) And this is expected to continue, with about a 70% increase in the number of annual deaths directly attributable to AMR by 2050, reaching 1.91 million in 2050.  Within the next 25 years, more than 39 million people (about twice the population of New York) are predicted to die from antibiotic-resistant infections over the next 25 years. (2)

Figure 1, Reference 3

This is why continuously reducing IRPs in the air and on surfaces will help to reduce whatever pathogens emerge, as well as existing pathogens.  In addition to antibiotic controls, facility control measures for continuous removal of indoor pathogens are a One Health approach, with CASPR’s continuously active indoor air cleaning.    

CASPR is a One Health Strategy in Preventing Spread of AMR Pathogens

In September 2024, a global AMR conference was held.  Just a few minutes before the start of this meeting,  the prime minister from Barbados stated, “Imagine what happens if you get an infection from going into the garden or having a baby or going to the dentist…These are things that can bring your life to an end within 48 to 72 hours if the particular antibiotics that you’re using [are] not effective.”  It seems like prevention of these AMR outbreaks with CASPR, a continuously active indoor air cleaner, is the continuous vigilance needed, consistent with a One Health approach to protection of humans, animals, plants, and the environment.    

 

 

  1. Centers for Disease Control and Prevention (CDC) website. One Health. Accessed 11/24/2024 at About One Health | One Health | CDC
  2. American Medical Association, Medical News & Perspectives ed. Kate Schweitze Associate Managing Editor: UN Meeting Highlights Antimicrobial Resistance “Epiphany”—Lack of Antibiotic Access Is a Key Driver. Published Online: November 8, 2024. doi:10.1001/jama.2024.21
  3. GBD 2021 Antimicrobial Resistance Collaborators, Global burden of bacterial antimicrobial resistance 1990–2021: a systematic analysis with forecasts to 2050. Lancet, 2024; 404: 1199–22.

 

Avian Flu Blog Banner

Understanding and Addressing the Threat of Avian Flu

by Blog

Recent reports about avian flu, particularly the H5N1 strain, have emerged, with more than 40 cattle facilities testing positive since March 2024, as of this writing. About 20 percent of retail milk tested is positive for the virus.1 Therefore, avian flu poses a significant threat to animal health and a potential threat to human health. Global experts have been closely monitoring this threat, now reality, since 2020.

While only one symptomatic case of avian flu among a farm worker in Texas was investigated last month, experts are closely watching to monitor other farm workers with surveillance testing, and assessment of any symptoms of illness. Concerns about the potential threat of human-to-human transmission has been expressed, with the CDC (Centers for Disease Control and Prevention) now testing wastewater supplies to detect any spikes in flu that could be attributed to Avian Flu. 2

Originally detected among poultry and wild birds, avian flu virus or highly pathogenic avian influenza (HPAI) spreads rapidly, expanding its reach, infecting various animal species. During fall and spring wild bird migrations, avian flu cases can be expected to rise, particularly in-flight migration zones. This is why the US government allocated 200 million dollars towards a rapid response to the spread of avian flu this month. 3

 

CDC Image: https://www.cdc.gov/flu/avianflu/data-map-wild-birds.html

 

How quickly the virus has spread this year has surprised scientists, with this outbreak believed to have begun in December 2023. The origins of bird flu trace back to China’s Guangdong region in 1996, where a new highly pathogenic strain, H5N1, was first identified in a farmed goose. By 1997, the first human deaths from avian flu transmitted among farm workers were reported in Hong Kong. Since then, it has expanded its reach, infecting other animal species. Low pathogenic avian influenza, initially non-fatal in wild birds, can mutate into different strains of HPAIs in farm-raised poultry. HPAIs can, cause severe illness and death among birds. 4

 

Even in remote regions of the world, there is evidence for the global spread of avian flu. These include HPAIs found among wild birds in Antarctica’s Northern Weddell Sea. Veterinary pathologists, like Lineke Begeman, have been at the forefront, braving harsh conditions to analyze the impact of the virus on wildlife. 4 Their efforts provide crucial insights into the virus’s trajectory and its potential consequences. For more than two decades, global and US national public health authorities, defense and civil authorities have worked on avian flu preparedness and response.

 

How it Spreads: Bird flu viruses can infect humans when a sufficient amount of the virus enters a person’s eyes, nose, or mouth, or when inhaled. This transmission can occur through airborne virus particles, such as droplets or potentially dust, that are breathed in by a person. Additionally, transmission can occur when a person touches a surface contaminated with the virus and then touches their mouth, eyes, or nose. 5

Human infections with bird flu viruses typically occur following close, prolonged, and unprotected contact with infected birds. In such instances, individuals may encounter the virus through direct exposure to infected birds or their bodily fluids, such as saliva, mucus, and feces.5 Within poultry facilities, feces may dry out and become airborne during activity. These can be inhaled by workers in some facilities. Protective measures, such as gloves or other personal protective equipment (PPE), are essential to reduce the risk of infection during contact with infected birds or contaminated surfaces.

 

Prevention

Preventing avian flu requires avoiding exposure to sick or dead animals and birds, especially poultry. Protective measures, such as wearing gloves, masks or face shields and other appropriate PPE, are essential when farm workers are handling potentially infected animals. Intermittent cleaning and sanitation of surfaces is important. 5 Continuously operating engineering products can provide an extra layer of protection for reducing both air and surface contamination, like CASPR (Continuous Air & Surface Pathogen Reduction). Hazard and risk reduction is the goal of prevention activities customized for facilities.

 

Impact and Response

While human cases of avian flu remain rare at this writing, the mortality rate among those people infected is disturbingly high, exceeding 50%. However, the virus’s impact on animals has been devastating, leading to the slaughter of millions of farmed birds every year since 2020, mostly in Asia. In addition, avian flu is causing significant mortality among wild bird populations. 4 To assist in mitigation strategies, the US Department of Agriculture shared data, obtained through routine collections of wild bird samples, that identifies areas with an increased AIV risk. 6

 

Efforts to prevent avian flu include enhanced surveillance, biosecurity measures on farms, and vaccination programs with some strains to poultry in high-risk areas. However, challenges remain, including the reluctance of some nations to implement vaccination, due to trade barriers, loss of income to farmers and producers when birds found to be positive are slaughtered, and concerns about disease detection in vaccinated flocks.

 

Since March, the detection of H5N1 among dairy cows in the United States underscores the need for comprehensive monitoring and response strategies for the remainder of this year, and beyond. While the transmission of the virus to humans remains rare, the potential for animal to human transmission highlights the importance of vigilant surveillance and implementation of public health measures to limit the spread.

 

The Importance of Monitoring Spread

All the commercial milk supply in the U.S. comes from farms that participate in the Grade “A” milk program and follow the Pasteurized Milk Ordinance (PMO), ensuring safety. Pasteurization and diversion or destruction of milk from sick cows are crucial measures in the federal-state milk safety system.

 

USDA Image: See https://www.aphis.usda.gov/livestock-poultry-disease/avian/avian-influenza/hpai-detections/livestock

As of May 10, the USDA states that 46 facilities have tested positive, with 1 in 5 retail milk samples analyzed being positive for the virus on May 2, 2024. 7 The virus has been reported to spread from cattle to other mammals, namely a few barnyard cats and a raccoon, in addition to poultry and wild birds. This impacts food safety and security.

Evidence to date indicates that adaptation of the HPAI A(H5N1) virus has occurred, since it has become established among cows. What worries many epidemiologists is the risk to public health, should the virus continue to affect other parts of the food supply, such as pigs. Unlike cattle, pigs often are infected with other influenza A viruses and are genetically closer to being able to infect humans. A few of these influenza viruses have already adapted and infected humans. Should these pig viruses mutate or exchange genetic material with H5N1, a more virulent strain of the virus or even a pandemic strain is possible. Therefore, extra measures are needed to limit the spread of HPAI to pigs, and to carefully monitor pig populations for HPAI.

Recommendations and Conclusion

The FDA recommends against consuming raw milk or raw milk products, particularly from cows showing symptoms of illness or exposure to avian influenza viruses. Producers are urged to take precautions when discarding milk from affected cows to prevent further spread. Destruction of poultry in affected facilities is made with appropriate state and national food/agricultural safety workers and veterinarians.

 

For the last two decades, public health authorities have been developing preparedness plans to combat avian flu as a global health concern. Now, these are being utilized, along with the mobilization of funding for US activities. 8 The recent, rapid emergence and spread of HPAI is a cause for concern, necessitating urgent action for monitoring and surveillance of poultry and pig production farms, while escalating adherence to safety protocols. While human to human transmission has not been reported with this HPAI, efforts are underway and continuing to monitor and limit any additional mutations of HPAIs among animals that could potentially impact humans. The CDC asks health officials to maintain flu surveillance this summer despite transmission of seasonal flu viruses dropping to minimal levels in the Northern Hemisphere. Even in the off-season, staying alert of any signs of human-to-human spread will minimize the risk 9 of H5N1 transmission. Continued collaborative action among food production facilities, public health authorities, communities and civil authorities are essential to safeguard both the food supply and human susceptibility to any further HPAI mutations.

 

The timeline of H5N1’s global spread 4

1996: Detected in poultry in Guangdong, China

1997: First human deaths reported in Hong Kong

2005: Spilled over into wild birds in a major way; new strains emerge

2020: A strain emerges that can sustain in wild bird populations year-round

2020-22: Becomes endemic in wild bird populations

2021: Arrives in North America

2022: Detected in South America

2024: Confirmed in Antarctica

 

Resources
Bird Flu Outbreak in Dairy Cows Is Widespread, Raising Public Health Concerns | Infectious Diseases | JAMA | JAMA Network

 

https://www.reuters.com/business/healthcare-pharmaceuticals/cdc-makes-public-influenza-wastewater-data-assist-bird-flu-probe-2024-05-14/

 

https://www.reuters.com/business/healthcare-pharmaceuticals/us-provide-nearly-200-million-contain-bird-flu-spread-dairy-farms-2024-05-10

 

https://www.bbc.com/future/article/20240425-how-dangerous-is-bird-flu-spread-to-wildlife-and-humans

 

https://www.cdc.gov/flu/avianflu/prevention.htm#anchor_1647619154182

 

https://www.aphis.usda.gov/livestock-poultry-disease/avian/avian-influenza/wild-bird-surveillance-dashboard

 

https://www.bbc.com/future/article/20240510-bird-flu-in-cows-has-caused-concern-amongst-milk-drinkers-experts-say-its-still-safe-to-drink

 

Updates on Highly Pathogenic Avian Influenza (HPAI) | FDA

 

Citing H5N1 threat, CDC urges peak flu monitoring this summer – STAT (statnews.com)