The Silent Threat: How Poor Indoor Air Quality Affects Health

In most regions, the cost of ventilating facilities during the hot and cold months is a major driver for HVAC energy use by schools and businesses. Traditionally, ventilation has been the primary way to create a healthy and comfortable indoor environment. But this comes at a high cost. We hear from many facilities managers and engineers that ventilation can be very expensive, with the need to heat cold air in the winter and cool air in our increasingly hot summers. 

ASHRAE recognized the challenge with their new Standard 241, which advocates for the use of air cleaners, like Metalmark Tatama, in combination with outdoor air ventilation for meeting indoor air quality targets and controlling the spread of infectious aerosols. 

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The limitations of ventilation were also made obvious over the summer with the wildfire smoke cloud that brought unprecedented air pollution to a large swath of the U.S. – areas that were hundreds and even thousands of miles from the fires themselves. The threat is forecast to continue throughout the year and the coming annual wildfire seasons. This is the new normal. 

Yet another barrier to ventilation is that day-to-day outdoor air in urban areas is often unhealthy to breathe. The American Lung Association says that over a third of Americans live in areas with unhealthy air. 

Air pollution, often referred to as the silent killer, is becoming an even more pervasive environmental threat impacting communities globally. There are many causes of air pollution. Transportation emissions often come to mind first. As mentioned previously, in recent years, another trend has been on the rise around the world: wildfire smoke. In the US and Canada, for instance, wildland fires have resulted in miserable outdoor and indoor air quality across both countries. Data from the US EPA shows that wildfire smoke accounts for about 3x that of PM 2.5 emissions from transportation sources! More broadly, this air pollutant is raising concerns about a public health crisis across the globe because smoke particles can trigger acute health problems such as heart attacks, especially for those with chronic conditions, as well as lead to long-term issues such as dementia. 

Below, we’ll address how breathing polluted air affects our health and some of the environmental and climate consequences of common solutions for treating indoor air quality (IAQ).

Understanding Indoor Air Quality

IAQ is influenced by the composition of airborne particles and gases within enclosed spaces as a result of various sources such as building materials, occupant respiration and activities, cleaning products, outdoor pollutants infiltrating indoors (e.g., natural events such as wildfire smoke), and more. 

Even though wildfires have caused severe damage to properties and communities directly impacted by such disasters, recent research shows that wildfire smoke can be 10 to 100 times more lethal than the fire itself. For example, according to a report from the National Bureau of Economic Research analysis, wildfire smoke contributes to 16,000 deaths annually.  Economically, wildfire smoke is a growing burden, with its total annual cost in the U.S. estimated at $394 billion to $893 billion. This includes $117.5 billion to $202.5 billion in healthcare costs linked to wildfire smoke exposure and driving illnesses like asthma, respiratory, and cardiovascular issues.

These figures highlight the far-reaching and devastating consequences of wildfires beyond just the flames.

The Health Impact of IAQ

Recent studies suggest that polluted air affects our health in multiple ways, from respiratory issues to cardiovascular and even causing DNA damage and mental health problems.

Professor Francesca Dominici, a leading data scientist at Harvard University’s Chan School of Public Health (HSPH), focusing on public health, has been working on analyzing the healthcare records of Americans, especially those linked with exposure to fine/airborne particles. In the study, “Long-term Effect of Fine Particulate Matter on Hospitalization with Dementia”, (Lee et al., 2019), researchers found that a longer exposure to fine particles increased hospitalization for Alzheimer’s disease. 

Furthermore, a longitudinal study of over 1.2 million Californians shows that breathing in wildfire smoke particles, in particular, increases the risks of dementia by 21%. What’s more, this effect is more pronounced with smoke than other PM pollutants. These findings are consistent with those of other research and highlight the need to take measures to mitigate air pollution, especially in the ever-neglected indoor environment. 

So, how does air quality affect health? HSPH’s Professor Marc Weisskopf suggests that fine particles not only damage our cardiovascular system but can also reach the brain and affect our immune system and health in general. Direct physiological studies in mammals demonstrate that smoke can cause long-lasting inflammation in the brain, specifically targeting the hippocampus—a region critical for learning and memory. Studies on mice exposed to smoke showed that this neuroinflammation can persist for over a month, leading to potential long-term neurological effects, including behavioral changes and cognitive impairments.

The situation gets worse in tightly insulated environments, such as those of highly energy-efficient buildings, if air quality is not treated properly. When polluted air becomes trapped indoors, it adversely affects the cognitive performance of occupants. The effects could be felt in the form of anxiety to lower accuracy and ease of problem-solving.

Let’s look at these impacts in greater detail:

Pulmonary Problems: Long-term exposure to air pollution can trigger respiratory issues, including asthma, bronchitis, and other lung diseases. Fine particles can irritate the respiratory duct, resulting in coughing, difficulty breathing, and sneezing. It can also lead to chronic illness, such as reduced lung function and increased risks of lung cancer.  

Cardiovascular Complications: Research shows that air pollution affects the cardiovascular system, including triggering heart attacks and strokes. The toxic pollutants can lead to inflammation in arteries that results in complications like abnormal heart rhythms. 

Brain Disorders: The latest research corroborates that long-term exposure to fine particles can increase the chances of Dementia–such as Alzheimer’s disease–Parkinson’s, and other neurocognitive diseases.

According to the US EPA, people spend around 90% of their time indoors, and indoor exposure to air pollutants is, therefore, highly consequential.

Vulnerable Population

Children, the elderly, and individuals with pre-existing health conditions are susceptible to polluted air, and protecting their health should be a top priority.

How to Mitigate the Effects

Addressing IAQ concerns requires proactive measures to ensure a healthy indoor environment. While we cannot directly control the outdoor environment, we can effectively manage indoor air impurities by implementing the following strategies:

• Control Indoor Sources: Identify and address sources of indoor air pollution, such as smoking and vaping, choices of building materials and furniture, and volatile organic compounds (VOCs) from paint, finishings, and cleaning products. Utilize exhaust fans to remove pollutants at their source.
• Keep Indoor Spaces Ventilated when Possible: If outdoor air quality is reliably clean, implement proper ventilation and filtration systems or open windows to allow fresh air to enter and stagnant air to exit. 
• Use Air Cleaners: Invest in air cleaners equipped with high-efficiency particulate air (HEPA) filters to capture and remove airborne pollutants effectively.

Air Cleaning and Climate Impact

With increasing threats from outdoor sources, such as wildfire smoke, and indoor sources like airborne viruses, it is essential for commercial buildings—including schools, hospitals, and offices—to implement proper air cleaning measures.

Most traditional HVAC systems in these commercial spaces operate sub-optimally, especially given the demand for improved IAQ. Upgrading to advanced air cleaning systems with higher ventilation effectiveness is crucial. This shift involves moving beyond theoretical air change rates or efficiency metrics to adopt solutions with proven ventilation equivalent efficiencies. Air cleaning technologies must not only filter contaminants entering the HVAC systems but also enhance the overall quality of air cleaning.

Improving IAQ is not only a matter of health; it tightly intersects with climate and energy considerations. HVAC systems drive about 40% of building energy use, contributing to massive greenhouse gas emissions. By investing in air-cleaning technologies that enhance air cleaning and reduce the dependence on ventilation, buildings can reduce HVAC energy use by as much as 50%, thereby decreasing their overall energy consumption.

Concluding Thoughts

While air pollution is a pervasive threat to health, taking preventive measures and improving facility management practices can help. More specifically, addressing IAQ problems requires comprehensive and innovative solutions for treating indoor air pollutants effectively, safely, responsively (to data), and energy efficiently.