Best Practices for Indoor Air Quality Monitoring

We spend most of our lives indoors, and that can be a problem if the air quality isn’t good. Poor air quality can lead to symptoms such as headaches, fatigue, allergy flare-ups, increased incidences of respiratory infections, and even decreased lung capacity. For employers, that means a workforce that’s never feeling at their best, and a potential liability if the air quality in your workplace is particularly poor.

Monitoring the air quality of your premises is a simple, effective way of determining if air quality is a problem you should be concerned about. Care homes, apartment complexes, office buildings, schools, churches, and more can all benefit from taking simple steps to review and improve their air quality in order to reduce sickness, boost performance, and improve the quality of life of employees, guests, and visitors.

    Best Practices for Indoor Air Quality Monitoring

    What is indoor air quality

    Indoor air quality refers to the chemical composition of the air inside a particular building, especially as it relates to human health. At sea level, “air” is typically 78% nitrogen, 21% oxygen, and trace amounts of other gases, such as carbon dioxide (0.03%), methane (0.0002%), and hydrogen (0.00005%). At normal levels, harmful gases such as carbon monoxide and ammonia exist only in tiny amounts, too little to do us any noticeable harm.

    When indoor air quality is poor, harmful gases build up to levels that can cause irritation or worse. Many workplaces are closed environments, with sealed windows and heating or cooling systems recirculating air. Under these conditions, even a small increase in a harmful gas can lead to prolonged exposure, increasing the severity of the reaction. That’s why understanding your indoor air quality is important, to protect the health of everybody who enters or works in your premises.

    Some workplaces are bound by guidelines for what is considered acceptable indoor air quality. Air quality guidelines for schools are set by the Environmental Protection Agency (EPA), for example, because children’s lungs are still developing and exposure to harmful gases could have detrimental long-term effects on their health.

    Contagious respiratory infections are also at the forefront of everybody’s minds since the onset of the COVID-19 pandemic. Eliminating harmful gases and pollutants from the air isn’t the only way to protect others, and following the EPA’s guidelines for air quality in schools during COVID-19 is a good way of protecting your property and those who live or work there.

    Indoor air quality in healthcare facilities is also of paramount concern because of the heightened risk of airborne transmission of infections, and the immunocompromised state of most patients. Year-round, but especially during flu season and throughout the coronavirus pandemic, indoor air quality in hospitals should be closely monitored to ensure the health and wellbeing of all inside. This limits contagion and also protects medical equipment that may be sensitive to temperature, humidity, and electrostatic buildup.

    Best Practices for Indoor Air Quality Monitoring

    Indoor air quality standards

    So what are the standards for indoor air quality, and who governs them? Most premises are covered by EPA guidelines, which provide information about what contaminants are considered dangerous, and in what quality. For example in domestic homes, radon gas, mold, carbon monoxide, and allergens should be monitored and controlled wherever possible. For commercial buildings, the American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE) provides guidelines for architects, property owners, and contracting professionals to help improve airflow and overall air quality.

    The Occupational Safety and Health Administration (OSHA) doesn’t provide any standards for indoor air quality, although it does regulate ventilation and specific contaminants. Generally speaking, businesses should test their premises for harmful gases such as radon and carbon monoxide, ensure adequate ventilation, and take measures to protect employees from hazards such as exposure to asbestos or construction dust.

    It is possible to be within the tolerable indoor air quality parameters of EPA/OSHA guidelines and still create an environment with poor indoor air quality, which is why additional monitoring is good practice. Poor air quality is detrimental to the health and wellbeing of anyone inside the building, and can have a negative impact on workplace productivity and morale.

    Indoor air pollutants

    Many substances are classed as pollutants in indoor air, from gases such as carbon monoxide, to lead and asbestos particles, secondhand smoke, and more. These pollutants get into the air in a variety of ways, from deliberate introduction to construction byproducts, machinery malfunctions, or even from the surrounding atmosphere. Therefore building managers must take a multifaceted approach to mitigating potential pollutants. Indoor air monitoring is advisable because it can quickly identify contaminants and allow property owners to focus on the appropriate remedies, especially as some pollutants are odorless, colorless gases.

    Top 10 types of indoor air pollutants

    Carbon monoxide (CO)
    Fossil fuel combustion — vehicle exhausts, space heaters, furnaces
    Odorless, invisible gas
    Fatigue, headaches dizziness, nausea, confusion, and death
    Nitrogen dioxide (NO2)
    Fossil fuel combustion
    Strong, harsh odor. Liquid at room temperature, or reddish-brown gas
    Irritating to eyes, nose, throat, bronchitis, pulmonary edema
    Breakdown of radioactive materials in the ground
    Odorless, invisible gas
    Increased risk of lung cancer
    Used in construction materials (composite woods, glues, paints, fabric, and paper products)
    Colorless gas with a strong, pickle-like odor
    Irritating to eyes, nose, throat, increased risk of some cancers
    Tobacco smoke
    Burning tobacco products
    Gray-white smoke with distinctive odor that leaves a yellow residue behind
    Irritating to eyes, nose, throat, pneumonia, bronchitis, increased risk of lung cancer
    Lead particles
    Breakdown of lead paint (used before 1978)
    Fine blue-white dust 
    Damage to brain, nervous system, kidneys, and red blood cells
    Asbestos particles
    Breakdown of asbestos-containing products (floor and ceiling tiles, textured ceilings)
    Fine or stringy white-gray dust
    Coughing, lung inflammation, mesothelioma, asbestosis, lung cancer
    Volatile organic compounds (VOCs)
    Emitted by paint, solvents, adhesives, cleansers, and disinfectants
    Invisible gases that may or may not smell
    Irritation to eyes, nose, throat, headaches, kidney and nervous system damage, fatigue, increased cancer risk
    Fungal growths in damp areas
    Musty-smelling, green, gray, or black blotches on walls and surfaces
    Trigger allergies and asthma, eye and throat irritation, difficulty breathing, headaches, fatigue
    Chemicals introduced to treat or prevent infestations
    A variety of gases, liquids, powders, and pellets
    Irritating to eyes, nose, throat, damage to nervous system, liver and kidneys, increased risk of cancer

    The prevalence of each pollutant in a property will depend on a multitude of factors. Some, such as lead and asbestos, are more commonly found in older buildings. Others, such as mold, usually only occur when there is an underlying problem such as a water leak or condensation buildup. And some can be introduced through natural sources like the ground the property is built on.

    The first effect of poor indoor air quality is usually low-level irritation. Runny eyes and noses, coughs, and increased occurrences of asthma and allergy flare-ups can all be a sign that there’s something bad in the air. Prolonged exposure can result in a range of chronic conditions such as bronchitis, fatigue, and damage to the central nervous systems, kidneys and liver. In worst-case instances, people in environments with high levels of air pollutants could develop cancers or pulmonary edemas. Inhaling carbon monoxide or nitrogen dioxide can even cause death outright.

    Best Practices for Indoor Air Quality Monitoring

      Causes of indoor air pollution

      Identifying the source of potential pollutants in the air is an important step in maintaining good overall indoor air quality. There are five main areas to consider.

      • Furnaces and heaters

      The source of some of the most imminently dangerous indoor pollutants is usually the furnace or heaters. Burning fossil fuels like natural gas produces several dangerous compounds, including carbon monoxide and nitrogen dioxide. Always ensure your heating equipment is properly installed and routinely maintained. If you don’t invest in any other kind of indoor air monitoring, ensure you have a carbon monoxide detector.

      • Leaks and condensation

      Mold loves wet environments, and an untended leak will quickly attract its own colony. While most molds are harmless, some, such as black mold (Stachybotrys chartarum) can be dangerous to humans. Black mold grows on high-cellulose materials such as wood, gypsum board, and paper. That means if you have a leak in a building, it provides an ideal environment for black mold to grow. Check your water pressure and usage to spot leaks fast, and pay attention to corners where condensation regularly occurs. You can treat surfaces with antifungal washes to prevent mold growth, and increasing air circulation can stop condensation from forming.

      • Construction materials

      Most property owners are aware of the risk of asbestos, which was widely used in construction materials such as floor and ceiling tiles and textured surface coating. Even today asbestos remains in use in the USA, although it is regulated by the EPA. Asbestos is still commonly found in roofing products, gaskets, and more. Asbestos is only harmful when it is inhaled, so as long as it remains intact it doesn’t pose any known health risk. However all potential sources of asbestos should be tested by a professional prior to any construction work, and removed by specialist companies if asbestos is detected. Care should also be taken to prevent damage to any materials that may contain asbestos.

      Related: How to do a post-construction clean properly

      Even if your premises is new enough for asbestos to be of little concern, modern construction materials may pose other risks to those inside. Formaldehyde is a common preservative used in the manufacture of composite wood products (hardwood plywood, particleboard and medium-density fiberboard), building insulation, glues, lacquers, paints, fabrics, and more. Almost every building will contain several sources of formaldehyde. While individually they may not produce enough formaldehyde to become a problem, building managers should ensure there is adequate ventilation, especially in new or recently renovated properties.

       The final concern construction materials pose is from VOCs. These are gases emitted from materials such as paints, varnishes, solvents, preservatives, cleaners, disinfectants, construction materials, copy paper, and marker pens. That sharp scent most of us enjoy of “fresh paint” or “new car” is often a hallmark of VOC emissions, although not all VOCs have an aroma. Most VOC exposure occurs indoors, where concentrations can be up to ten times higher than outside. While the majority of VOCs cause low-level irritation, prolonged exposure to some can result in liver, kidney, or nervous system damage, so it’s important to keep areas well ventilated. 

      • Human activity

      Some indoor pollutants are introduced either deliberately or through carelessness. If you’re busy fighting a fly infestation in the office kitchen, you might not think about the effects the bug spray you’re using is having on the air quality in the rest of the building. As a rule of thumb, whenever you want to introduce pesticides into a building, it’s better to hire a pro to do the job. Not only will they use the most effective treatments, they’re also trained in how to use their products safely around people.

      Tobacco smoke and vehicle exhaust fumes can also inadvertently end up affecting indoor air quality, even in smoke-free buildings. If smokers congregate near doors or open windows, for example, the smoke can easily waft inside. And if the building is in a city center or other high-traffic area, consider the impact of vehicle fumes before opening a window.

      • The environment 

      Sometimes pollutants occur naturally in the surrounding environment. The most obvious example is radon gas, which is caused by the breakdown of natural radioactive elements in the ground. The EPA monitors radon levels in the USA and while there is no “safe” amount of radon exposure, they advise that homes with radon levels of four picocuries per liter (pCi/L) or higher should take measures to address the problem. (A picocurie is a measure of radioactive decay.)

      Counties are categorized according to three risk zones. Zone 1 counties have the highest potential to exceed 4pCi/L of radon. Zone 2 counties are predicted to measure 2-4pCi/L, and Zone 1 counties are the lowest risk, averaging less than 2pCi/L. While there is some variation between counties depending on the geological makeup of each specific area, the south-eastern states and north-westernmost counties are in the lowest risk zone, while much of the Midwest and Appalachia is in the highest risk zone. Regardless of zone, each property should undergo its own radon assessment, as small pockets of radioactive material in the ground can cause one building to have high radon readings even if all the neighboring buildings are below the danger threshold.

      Best Practices for Indoor Air Quality Monitoring

      How to improve indoor air quality

      Although poor indoor air quality is a common problem, it can be easily remedied. The first step is to understand the current condition of your building’s indoor air through monitoring for pollutants and taking action against specific problems. An indoor air quality monitor costs around $100, and is a great investment for any business. 

      Another valuable source of information is the EPA’s daily Air Quality Index (AQI) report. This report measures five major air pollutants and assigns a number from 0-500, based on current air conditions. The higher the number, the poorer the air quality. For ease, this number is also color coded into six bands based on the overall quality of the air.


      Pollutants measured by the EPA

      • ground-level ozone
      • particle pollution (also known as particulate matter, including PM2.5 and PM10)
      • carbon monoxide
      • sulfur dioxide
      • nitrogen dioxide

      EPA AQI Index

      Air poses little or no risk
      Slight risk to those sensitive to pollution
      Unhealthy for sensitive groups
      Sensitive groups experience health effects, general public typically unaffected
      General public experience health effects, sensitive groups experience serious health effects
      Very unhealthy
      All population at risk of increased health effects
      Emergency conditions, everyone affected

      While there is no indoor air quality index, knowing the conditions outside is a good way of determining increased risk inside a building.

      How indoor air quality testing works

      Small monitors placed in testing areas analyze the air for gas and particulate matter, and report findings either as a unit display or through smartphone apps. Many consumer-grade models test for common pollutants such as CO2, formaldehyde, and particulate matter, as well as temperature and humidity. Most also have VOC sensors, and more expensive models will also test for radon and less common gases.

      These machines are great for providing a fast overview of your building’s indoor air quality and assist in ongoing monitoring, although they are rarely sensitive enough to provide accurate readings of all major pollutants. Mold, for example, is often identified by indoor air quality products when they detect particulate matter. It takes a separate test to confirm the presence of mold (rather than, say, harmless dust particles of approximately the same size) and to identify the mold species that is present. You can also test for bacteria and other pathogens and get instant results using ATP meters.

      If you identify a problem with your indoor air, it’s worth the extra expense of a specialized test to identify exactly what’s going on. These unobtrusive tests usually absorb a sample of the air using charcoal, which is then analyzed in a lab to give an exact measure of what’s in your air.

      Best Practices for Indoor Air Quality Monitoring

      Improving indoor air quality

      Once a pollutant has been identified, it’s important to treat the source. That could be as simple as opening windows and introducing fans to increase ventilation after construction work has finished to allow VOCs and formaldehyde to escape, or it could mean more extensive remediation to treat decaying lead or asbestos products, a water leak, or radon gas. A portable indoor air quality sensor can help identify the origin of a pollutant if it’s sensitive enough to pick up differences in pollution levels nearer or farther away from the source.

      If there is no specific source, just general poor air quality caused by external air conditions and low ventilation, there are still ways to address the problem and improve the air in your property. 

      Improving indoor air quality starts with HVAC maintenance. If your premises already has a heating and cooling system, you can harness it to circulate the air and remove pollutants. More and more businesses are using hospital-grade air filtration systems to protect employees and visitors, and to reduce exposure to airborne allergens and pathogens. But whatever your HVAC system, you can use it to improve your indoor air quality by taking just a few simple steps.

      • Change HVAC filters regularly
      • Invest in UV lights for your HVAC system to disinfect the air
      • Open vents to allow increased airflow
      • Install a humidifier to minimize dust and allergens

      Other indoor air quality solutions include cleaning more frequently or thoroughly, reducing clutter that can attract dust, and installing plants. While that potted fern isn’t going to clean the air overnight, plants do reduce a small amount of VOCs from the air, and they have been shown to alter indoor microbial conditions and potentially prevent harmful bacteria from gaining a foothold.

      Related: All about commercial cleaning

      The benefits of good indoor air quality 

      Fresh air doesn’t just feel and smell better, it’s better for us. Monitoring the air quality in your office, school, or medical facility leads to a happier, healthier environment, with higher productivity and less absenteeism. That makes an indoor air quality meter a good investment, whatever your business.