Indoor Air Quality: Hidden Health Risks & How to Improve the Air You Breathe
It might surprise you to know that Americans spend about 90% of their time indoors, where concentrations of some pollutants are 2 to 5 times higher than outdoors. Between worsening air conditions and the survival of remote work, the amount of time that Americans spend outside the home each day has dropped by nearly half since 2020. Not only are people spending more time than ever indoors, but many don’t realize the hidden dangers of indoor air pollution and its effects on their health. Learning how to improve indoor air quality is essential to reducing these risks.
Americans spend about 90% of their time indoors, where concentrations of some pollutants are 2 to 5 times higher.
Despite the increasing amount of time that people are staying indoors, poor indoor air quality (IAQ) is continuously being linked as a contributing factor to a myriad of serious health issues. Poor IAQ is a risk factor for several of the world’s leading causes of death, including heart disease, pneumonia, stroke, diabetes, and lung cancer, making it one of the leading risk factors for death globally. In fact, the World Health Organization (WHO) has called indoor air pollution "the world's largest single environmental health risk."
The World Health Organization has called indoor air pollution "the world's largest single environmental health risk."
It’s estimated that $10 billion to $70 billion is spent annually on Sick Building Syndrome (SBS) in commercial workplaces. SBS is caused by poor indoor air quality, typically characterized by headaches and chronic respiratory problems. In 2022, the U.S. Environmental Protection Agency (EPA) created and pushed the Covid-catalyzed Clean Air in Buildings Challenge, a call-to-action to building owners, operators, and leaders, recommending principles and actions designed to improve indoor air quality. The goal was to reduce the spread of the virus, airborne particles, and other contaminants to support occupant health.
With so many factors at play, it’s no wonder that interest in improving indoor air quality (IAQ) is increasing - indoor air quality is the most researched building attribute and was also presumed to be the most important by building professionals. IAQ is a fast-growing wellness trend for good reason - it affects almost every system of health that we at Frequency prioritize: cardiovascular health, circadian health, cognitive health, emotional sustainability, resilience, and respiratory health.
What is Good Air Quality
So, how do you determine what qualifies as good indoor air quality and what steps can you take to improve it? The EPA’s Air Quality Index (AQI) helps people determine good air quality from poor air quality at a glance, but at the end of the day, what determines the quality of air is its concentration of pollutants. When the AQI is between 0-50, the air is considered safe, and the concentration of pollutants in the air is considered negligible. However, as the concentration of pollutants increases, people begin to suffer from the effects of poor air quality, starting with people who are sensitive to changes in air quality, such as people with asthma or heart disease.
Since poor air quality causes a host of health issues, it may be tempting to think that the effect of good air quality is simply the absence of poor health; that it removes the negative effects of poor air quality. So rather than providing added benefits, good air quality simply removes the negative effects of poor air quality. However, the old definition of health as “the absence of disease” is rightfully being replaced with something more like this from the World Health Organization: “the state of complete physical, mental, and social well-being, and not merely the absence of disease or infirmity.”
What Air Quality Affects
Poor air quality affects almost every system of health that we at Frequency prioritize. The following studies, and more, convinced us that IAQ should be a focal point in our research:
Poor air quality negatively affects cardiovascular health: A 2023 study linked a decline in air pollution with a decline of heart attacks and premature deaths caused by cardiovascular diseases. In 2024, the EPA determined that air pollution can exacerbate existing cardiovascular disease. This is significant, given that heart disease is the leading cause of death in the U.S.
Air quality affects circadian health: A 2023 study found an association between air pollution and reduced sleep quality, while a 2020 study discovered that pollutants play a role in disrupting the circadian rhythm.
Air quality has an effect on cognitive health: Researchers found in a 2022 study that even short term exposure to air pollution is associated with cognitive and executive dysfunction, while a 2022 review concluded that air pollution may impair cognitive function over the course of a person’s life. Additionally, a 2023 meta-analysis from Harvard researchers concluded that certain common indoor air pollutants might be a risk factor for dementia.
Poor air quality even affects our emotional sustainability: According to a 2023 review, there’s emerging evidence that exposure to air pollutants may lead to neurocognitive disorders and affect mental health. Additionally, a 2019 study of large U.S. and Denmark populations discovered that air pollution is associated with increased risk of psychiatric disorders, including depression, schizophrenia, bipolar disorder and personality disorder. A 2022 review found that 73% of reviewed studies reported higher mental illness symptoms and behaviors in people who had more exposure to air pollution. The review’s lead researcher, Clara G. Zundel, said of the study in a World Economic Forum report, “People who breathe polluted air experience changes within the brain regions that control emotions, and as a result, they may be more likely to develop anxiety and depression than those who breathe cleaner air.”
People who breathe polluted air experience changes within the brain regions that control emotions, and as a result, they may be more likely to develop anxiety and depression than those who breathe cleaner air.
Poor air quality affects our resilience: A 2021 study found that exposure to larger particulates is associated with reduced heart rate variability (HRV), which is a measure of a person’s ability to react to physical and mental stressors. Higher HRV means that you’re able to recover more quickly from stressors. Additionally, the results of a 2022 study suggest that long-term exposure to air pollutants, specifically smoke, reduces HRV functioning.
Perhaps least surprisingly, poor air quality has a negative effect on our respiratory health: According to a 2021 review, the effects of indoor air pollution are wide ranging, affecting lung development in childhood, incidence of lower respiratory tract infection, and both disease development and morbidity for COPD and asthma. In fact, according to a Global Burden of Disease (GBD) study, 6.7 million deaths were regarded as being caused by air pollution in 2019.
How to Prioritize Good IAQ
If you're wondering how to improve indoor air quality at home, there are a few key steps you can take. From HEPA air purifiers to HVAC filtration, here’s how to get started. First, you can upgrade your filtration systems or, for renters, add smaller air filtration systems to your space. We have different recommendations for air purification depending on the desired solution.
For individualized, room-level air purification, we recommend standalone HEPA13 or EPA12 units. This is a generic product, but multiple different brands supply these filtration units. Be sure to place these units in centralized or high traffic areas, and make sure they’re not blocked or hidden, so that they work properly. We recommend these filtration units to all projects that don’t have a proper HVAC fit for the other types of purification, and members of our team use them in their personal homes.
For whole-building HVAC integration, we recommend electrostatic in-duct filtration. This type of filter is low maintenance. It effectively captures all particle sizes, and reduces face loading, which is when the surface of a filter becomes so clogged with dust and dirt that airflow and filtering efficiency is reduced. We ran a study on the efficacy of this tech in a Washington, D.C. co-living building where the units remain. We’re currently pushing to get them approved by the California Air Resources Board to fit with California Title 24 requirements for air filtration.
For HVAC-integrated purification, and microbial and VOC reduction, we recommend bi-polar ionization (BPI) solutions. BPI uses the same process of ionization found in nature. BPI works by releasing ions via a generator which bind to particulates and cause them to cluster together. The clustered particulates are then large enough to become trapped by your existing air filter when they would have otherwise been microscopic enough to pass through. When the generator’s sensor detects pollutant levels that are too high, the system kicks on and operates until the sensor verifies that the air is purified. We at Frequency are currently running pilots of this tech in a yoga studio, a gym, a 55+ multifamily community, and our team members’ personal homes.
Another tool that can be used to effectively filter indoor air is a green wall. Green walls serve a dual purpose: not only do they naturally filter air, but they help us feel safe and relaxed. Plants contain biophilic patterns (naturally occurring mathematical patterns), and we’ve evolved to view the presence of uninterrupted biophilic patterns as indication that an environment is free of predators.
Given its comprehensive effect on so many different facets of health, both mentally and physically, it’s easy to see why indoor air quality is important and should be prioritized. To learn more about indoor air quality and its effects, check out Episode 14 of the Finding Frequency Podcast as well as an earlier article covering indoor air quality that we published on our blog.