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​​​​Recent Air Pollution Events

​​Outdoor air quality has become a hot topic recently, most notably with the Canadian wildfires and the unsafe levels of air pollution they produced across large areas of the United States. These types of air pollution events are likely to increase in frequency and intensity in the future due to worsening climate change. In this article, we’ll discuss air pollution levels and common pollutants, we’ll look at the specific instance of air pollution from the Canadian wildfires and we’ll establish ways to protect ourselves from poor outdoor air quality.

​Air pollution is broadly defined as chemicals or particles in the atmosphere that pose threats to human health and the environmental. Air pollution can be emitted directly into the atmosphere from a source (known as primary air pollutants), or the pollution can be formed within the atmosphere by chemical reactions of precursors (known as secondary air pollutants). The most common air pollutants are called Criteria Pollutants (as defined in the U.S. Clean Air Act​) and consist of ground-level ozone, particulate matter, sulfur dioxide, carbon monoxide, nitrogen oxides and lead.^1​ Among these, the two pollutants most likely to cause unsafe air quality on a daily basis are ground-level ozone (also known as smog) and particulate matter (especially particulate matter under 2.5 micrometers in size, known as PM2.5). Smog is typically produced through reactions of nitrogen oxides (NOx) and volatile organic compounds (VOC) in the presence of heat and sunlight.^2​ Particulate matter can be emitted directly from sources like smokestacks or fires, or formed by complex chemical reactions of other pollutants, like those produced by power plants, industries and automobiles.^3​ The combustion of fossil fuels and biomass is strongly associated with these pollutants and their precursor compounds.^4​ Climate change is expected to make the conditions for the formation of these pollutants more favorable.^4​ For example, heat and sunlight make it more likely to form smog and hot, dry weather can promote wildfires and dust storms.

The level of air pollution is measured with the Air Quality Index (AQI). An AQI is established by the EPA for five of the six Criteria Pollutants mentioned above (with the exception being lead). The AQI for each pollutant runs from 0 to 500, with 100 established as the short-term air quality standard for protection of public health.^5​ AQI values below 100 are considered acceptable, while values over 100 are unhealthy.^5​ Values just over 100 are mostly of concern only to sensitive groups, while values around 200 indicate unhealthy air quality for everyone.^5​ AQI values over 300 are considered hazardous and can pose serious health threats to all humans.^5​ Health effects from short-term exposure to air pollution include irritation of the respiratory system, coughing, decreased lung function, wheezing, shortness of breath and asthma attacks.^6​ The health effects can become severe at high AQI values or for sensitive individuals at lower AQI values, including bronchitis, increased susceptibility to respiratory infections, aggravated lung or hearth disease, heart attacks and even death.^7​ Long-term exposure to air pollution has been linked to reduced lung function, chronic bronchitis, stroke, heart disease, COPD, cancer and premature death.^7​

The 2023 wildfire season has been the worst in Canadian history, with over 10 million acres burned.^8​ For reference, the state of Maryland consists of around 6 million acres of land.^9​ The wildfire season has almost certainly been exacerbated by climate change, causing longer and more intense periods of hot and dry weather. The air pollution from the Canadian wildfires reached a peak for many in the U.S. around June 7, with New York City recording Air Quality Index (AQI) measurements greater than 250 and Bethesda recording AQI measurements of over 150.^10​ The wildfires continue to pose a threat weeks later, with Chicago measuring AQI levels over 200 on June 28.^11​

This easiest way to protect ourselves from outdoor air pollution is to simply stay inside! Most of our homes and offices are isolated from outdoor air enough to prevent high levels of air pollution from getting inside. If you must go outside during high AQI values, keep your outdoor activities brief and low intensity with periodic indoor breaks. Additionally, facemasks that filter high levels of fine particulates and that form an effective seal to your face, like N95 or KN95 masks, can reduce your exposure to air pollution. Know the AQI levels for your area​ and use those to determine stronger precautions when air pollution is particularly high. If you are sensitive to air pollution (children, older adults and people with asthma, lung disease or heart disease) have an action plan in case you start experiencing health effects from the decreased air quality. Avoid using volatile solvents or combustion engines when it is hot and sunny since you could promote the local formation of smog. We can also promote air quality by reducing our fossil use, which reduces primary pollutants and the precursors of many secondary pollutants. Reduced fossil fuel use also helps combat climate change, which has a tendency to worsen air quality. Air pollution does not always affect the local area where it is generated, as we’ve seen with the Canadian wildfires. We should each strive to be an environmental steward to protect air quality for ourselves and everyone around us!​

​Spotlight                                                                                                                                                                                                                                                                                     

Air Quality with Joseph Musa ​​Joseph Musa, P.E., is an Environmental Engineer in the Division of Environmental Protection (DEP) and serves as the subject matter expert on issues related to air quality regulations for the NIH Bethesda Campus.​ LEA​RN MORE​​​​

​​Take Action                                                                                                                                                                                                                                                                              

Protection from Air Pollution ​ ​It is important to take the proper steps to protect yourself from the harmful effects of air pollution. In this article, we list some steps you can take to reduce your exposure.​​ LEARN MORE​

NEMS Training                                                                                                                                                                                                                                                                         
Did you know? Approximately 20 PM2.5 particles side-by-side are equal width as a human hair. These tiny particles travel deep into the lungs and can cause severe health effects. To learn more about air pollution, please visit the NEMS Training webpage to view a short (20 minute) NIH environmental awareness training video.