The Case for an Indoor Air Quality (IAQ) Index in Health Care


Air quality.

(Adobe Stock 496425320 by stokkete)

The methods for quantifying the impacts or strength of science have evolved throughout history.

Venn Diagram: Three-Circle Venn Diagram: Air Monitoring and Purification

(Credit: Authors)

This Venn diagram explores how 3 essential elements of air purification and monitoring intersect:

Effective Air Monitoring

•Collects real-time data

•Analyzes air quality

•Detects pollutants and allergens

Ceiling Mount Air Purifiers

•Permanently installed

•Cover large areas

•Operate quietly

Rolling Floor Air Purifiers

•Are portable

•Position flexibly

•Clean the air with a targeted approach

Intersections

• Effective Air Monitoring and Ceiling Mount Air Purifiers mean continuous air quality control and high-efficiency purification for large spaces.
• Effective Air Monitoring and Rolling Floor Air Purifiers provide real-time air quality feedback with mobile air cleaning solutions for adaptable environments.
• Ceiling Mount Air Purifiers and Rolling Floor Air Purifiers offer a comprehensive air purification strategy utilizing both fixed and portable units for maximum coverage.
• Combining all 3—Effective Air Monitoring, Ceiling Mount Air Purifiers, and Rolling Floor Air Purifiers—gives you an integrated system to achieve 4-log purification (99.99%) of airborne particles, pathogens, and their carriers down to 0.1 microns.
• This setup offers extensive air quality monitoring and versatile purification options, ensuring optimal indoor air quality in any setting.

For example, the Richter Scale, developed by Charles F. Richter in 1935, used seismograph technology to measure the strength of earthquakes on a logarithmic scale from 1k to 8.6 (the largest earthquake on record).¹ It simplified complicated data through an at-a-glance magnitude index to help public health and safety officials anticipate impacts.

The Moment Magnitude Scale largely replaced Richter’s scale in the late 1970s,² and advances in seismograph technology enabled early warning systems such as the US Geological Service (USGS) ShakeAlert that detects the rumblings of potentially large temblors and sends alerts to communities before major shaking starts.³

Standardized, more sensitive, and accurate ways of measuring earthquakes improve our ability to cope with related impacts and exposures.

Similarly, advances in Indoor Air Quality (IAQ) monitor technology—see Sidebar, Technological Advancements in IAQ Monitors—suggest a scale that helps anticipate IAQ impacts by indexing levels of exposure in real-time; eg wall-mounted units can detect tremors of exposure to 0.1-micron particles linked to viral load and transmission based on particle size and shape profiling a heightened sensitivity that extends to volatile organic compounds (VOCs), chemical and other pollutants enhancedbyplug-and-play modules that detect certain contaminant types. (See Sidebar: “The Role of Shape in Identifying Microscopic Particles as Viruses” below article.)

Like a supercharged Richter Scale, an IAQ Exposure Index (Indoor Air Quality Exposure Index)—as a complement to EPA’s outdoor Air Quality Index or AQI — can help:

The Richter Scale, developed by Charles F. Richter in 1935, measured earthquake strength on a logarithmic scale, simplifying data to help public safety officials anticipate impacts. (Rafferty 2024) Replaced by the Moment Magnitude Scale in the late 1970s, advances in seismograph technology enabled early warning systems like USGS ShakeAlert, which detects rumblings and sends alerts before major shaking begins.³

Similarly, advancements in Indoor Air Quality (IAQ) monitor technology suggest creating an IAQ Exposure Index, complementing EPA’s Air Quality Index (AQI). Wall-mounted IAQ units now detect 0.1-micron particles linked to viral loads and VOCs, providing real-time exposure levels to better anticipate impacts.

The IAQ will

• Determine the scope of airborne exposures using a simple at-a-glance metric,
• Provide an early warning system, and
• Remediate indoor air by better managing airflow, ventilation, and purification to reduce infectious illness and other exposures.
  

The Need in Health Care

Health care facilities serve the needs of high-risk individuals—such as chemotherapy patients, the immune-compromised, those with respiratory conditions, neonates, and older persons—who are most susceptible to airborne exposures. Health care work also tops the list of high-proximity jobs involving close contact with others. Thus, a scale that provides an instant exposure metric for airborne pollutants may seismically impact this vulnerable community.

Placement of sensors is critical due to the way air moves through indoor spaces,

Since air is “liquid,” understanding widening exposures from an ocean oil spill helps convey the movement of pollutants in indoor air.

Understanding Airborne Exposures

Petroleum particles spread into and permeate the environment during an oil spill. Cleanup involves removing what you can see (eg, globs of oil), as well as unseen particles and gaseous pollutants wafting on currents. Over time, these may be the most harmful as they often escape detection and removal. When remediating a spill, well-placed optical, electrochemical, ultrasonic, and conductivity sensors detect oily particles and byproducts.⁴

Well-placed air sensors help detect what’s in the ocean of indoor air (see Sidebar, Common Air Pollutants in Health Care Facilities), and from an infection prevention perspective, viruses, bacteria, and fungi that may circulate in the air attached to other particles Trojan-horse style.⁵ (See Sidebar, "Airborne Pathogens 0 .1 Micron or Larger" below article.)

An Early Warning System for IAQ

As a seismograph detects even slight and unusual increases in ground motion in real time, providing an early-warning system for seismologists, a system driven by an IAQ Exposure Index can alert IPC and EVS staff of potential IAQ issues and spikes.
Continuous monitoring of air quality—and, say, providing a 1 to 10 metric for airborne viral load—will help enable early detection and intervention as a surveillance system to spot outbreaks and facilitate prompt responses to mitigate the spread of infections.

By identifying and quantifying levels of airborne pollutants, an IAQ Exposure Index can focus on eliminating sources of pollutants where possible, better managing airflows, improving ventilation, and integrating air purification with building management systems.⁶
A 3-circle system of air monitoring, ceiling-mount, and floor-based air purification best summarizes a system to reduce airborne-source infections. This system is based on the principle that purifiers closer to the breathing zone of occupants are most effective.⁷ (See Sidebar: “Three-Circle Venn Diagram: Air Monitoring and Purification” below article.)

Remediate by Managing Airflow, Ventilation, and Purification

Air—though life-giving—is a carrier of pollutants. Controlling the air through room pressurization and directing airflow is vital but insufficient. Since infectious exposure often occurs near the source, HVAC systems must remove, filter, and dilute contaminated air.

Room- or area-based sensors integrated with ceiling-mounted or freestanding air purifiers enable crucial proximity air cleaning to intercept pollutants at the source, protect the immediate exposure zone, and lower HVAC costs since cleaner air reaching the HVAC system reduces filter changes, electricity for operating cycles, and motor wear.

Conclusion
Success in protecting air quality based on an IAQ Exposure Index involves using an at-a-glance metric to simplify identifying complex airborne exposures. This metric provides an early warning system for airborne pathogens and lowers HVAC costs. It also produces a seismic shift in protecting human health by integrating real-time monitoring (diagnosis) and purification (treatment) to improve indoor air in health care facilities.

Sidebar: Technological Advancements in IAQ Monitors

The concept of monitoring indoor air quality (IAQ) began taking shape in the late 20th century, driven by increasing awareness of the health impacts of indoor pollutants. The first IAQ monitors were rudimentary devices that primarily measured particulate matter and basic gases such as carbon dioxide (CO₂) and carbon monoxide (CO). These early monitors provided limited data and required manual reading and recording, often making them cumbersome and less effective for continuous monitoring.

Numerous technological advancements have marked the evolution of IAQ monitors, making today's devices more accurate, user-friendly, and versatile. These advancements include improvements in sensor technology, integration with smart technologies, and enhanced data analytics capabilities.

Sensor Technology

Modern IAQ monitors use advanced sensor technology to detect a broader range of pollutants with greater precision. Sensors have become more sensitive and can now measure fine particulate matter (PM2.5 and PM10), volatile organic compounds (VOCs), humidity, temperature, and other parameters. Remarkably, some units can detect 0.1 micron-sized particles and particle shapes, promising an early warning system for viral exposure (see Sidebar: “The Role of Shape in Identifying Microscopic Particles as Viruses”).

Cloud computing and advanced data analytics have further revolutionized IAQ monitoring. Data collected by IAQ monitors can now be stored and analyzed over time, providing valuable insights into airflow patterns and trends in air quality.

An IAQ Exposure Index can predict potential air quality issues and suggest or initiate proactive steps—eg, ventilation, directed airflow, and sensor-integrated purification—to protect human health.

Sidebar: The Role of Shape in Identifying Microscopic Particles as Viruses

Viruses come in various shapes, each reflecting their unique structures. Here are the primary shapes:

Icosahedral: Think of Adenoviruses. They have an icosahedral shape, which means they have 20 triangular faces. This shape provides stability and symmetry.⁸

Helical: Consider the Tobacco mosaic virus. It is rod-like, formed by protein subunits spiraling around a central axis.

Complex: Look at bacteriophages. These viruses are complex, combining icosahedral and helical features, often with added structures like tails.

Summing Up: The shape of microscopic particles is crucial in identifying them as viruses.

Using advanced techniques like electron microscopy, X-ray crystallography, and Cryo-EM, scientists can see and differentiate these pathogens based on their unique forms. This knowledge is vital for diagnostics, vaccine development, and tracking outbreaks.

Sophisticated air monitoring systems can now also help identify viral shapes, ultimately helping us understand distribution patterns and prevent viral infections.

Sidebar: Common Air Pollutants in Health Care Facilities

Particulate Matter (PM)
Particulate matter (PM) is a mixture of airborne solid particles and liquid droplets. These particles, when inhaled, can impact health. Sources of PM in healthcare facilities include:

•Linens and bedding generate fine textile dust.

•Skin flakes from patients and staff. An average person sheds about 600,000 skin flakes every day, or 1.5 pounds of skin cells shed per year.⁹

•Indoor Activities: Certain medical procedures and laboratory activities can produce particulate matter.

•Construction Activities: Renovation and construction work within health care facilities can generate dust and other particulate matter.

•Outdoor Air: Particulate matter from outside can infiltrate the building through ventilation systems.

Pathogens
In health care settings, airborne pathogens are a significant concern, including:

•Bacteria

•Viruses

•Fungi: Molds and other fungi can grow in damp areas and release spores that may cause allergic reactions and infections.

Volatile Organic Compounds (VOCs)
Volatile Organic Compounds (VOCs) are chemicals that become airborne as vapors or gases. They are released from various sources within healthcare facilities, including:

•Cleaning agents: Many disinfectants and cleaning solutions emit VOCs, contributing to respiratory and other health problems.

•Medical equipment and materials: Some medical devices and materials can release VOCs.

•Building materials: Paints, adhesives, and synthetic materials used in the construction and maintenance of health care facilities often emit VOCs.

Chemical Contaminants
Health care facilities often use various chemicals that can contaminate the air, including:

•Disinfectants and sterilants

•Pharmaceutical compounds

Gaseous Pollutants

Gases such as carbon monoxide and nitrogen dioxide can originate from:

•Combustion processes: Heating systems, generators, and other combustion sources can emit harmful gases.

•Medical gas systems: Leaks and emissions from medical gas systems can introduce pollutants into the indoor air.

Sidebar: Airborne Pathogens 0.1 Micron or Larger

Influenza Virus: Commonly known as the flu, it can be spread through respiratory droplets.

• Rhinoviruses: These are a major cause of the common cold.
• Adenoviruses: These can cause respiratory, gastrointestinal, and other infections.
• Respiratory Syncytial Virus (RSV): A common cause of respiratory infections, especially in young children and older adults.

The sizes¹⁰ of some airborne bacteria in microns are as follows:

• Staphylococcus bacteria (commonly known as staph) are generally between 0.5 to 1.5 microns in diameter.
• Pseudomonas aeruginosa: Typically, these bacteria measure 1 to 2 microns in diameter and 5-8 microns in length.
• Mycobacterium tuberculosis: These bacteria are about 0.2 to 0.5 microns in diameter and 2-4 microns in length.
• Acinetobacter baumannii: Generally, they are roughly 0.9 to 1.6 microns in diameter.
• Legionella pneumophila is a bacteria approximately 0.5 to 0.7 microns wide and 1 to 3 microns long