Air Pollution 101

This section offers key information about air pollution and practical steps you can take to protect yourself and reduce exposure.

Types of Pollutants

Primary Pollutants

Emitted directly into the atmosphere from a source. Classically categorized as particulate matter (PM10 & PM2.5), volatile organic compounds, oxide gases (carbon monoxide, nitrogen oxide, sulfur oxide), ozone, lead, and smog.

Secondary Pollutants

Byproducts of primary pollutant interactions in the atmosphere. Emitted directly into the atmosphere from a source. Common examples include ground-level ozone, acid rain (sulfuric & nitric acid), peroxyacyl nitrates, particulate matter, & nitrogen dioxide.

Measuring it All: Common Metrics Used

Air Quality Monitoring Index | EPA

The AQI

Air Quality is primarily measured through the Air Quality Index. The score is measured from 0 - 500, ranging in gradation from good to hazardous. The AQI monitors ground-level ozone, carbon monoxide, sulfur dioxide, nitrogen dioxide, and aerosol levels. Indexes are calculated for each pollutant, where the pollutant with the highest risk factor takes precedence in determining the final score.

Learn more about the calculations used: https://document.airnow.gov/technical-assistance-document-for-the-reporting-of-daily-air-quailty.pdf

Aside from the AQI, raw pollutant concentrations and satellite measurements of various aerosols can better determine nuance in the region’s air quality. Databases from various monitors are being utilized to expand pollutant information globally.

You can follow global monitoring stations here: https://www.iqair.com/unep

Associated Health Risks

Pathophysiology of Air Pollution–Driven Disease. | The New England Journal of Medicine

Increased Disease Prevalence

Air pollution disrupts organ homeostasis through several triggers, like DNA damage, immune system dysregulation, oxidative stress onset, and organ function interference. As a result, air pollution causes chronic disease development and exacerbates existing conditions. Specifically, risks for cancer, as well as the speed of cardiovascular and respiratory disease onsets, are known to increase in polluted environments.

Outdoor air pollution and brain development in early childhood and adolescence | Trends in Neuroscience

Disproportionate Healthcare Risks

In children, air pollution increases respiratory infections, asthma, and bronchitis in adulthood. Prenatal exposure to pollutants disrupt normal fetal development, resulting in several developmental disorders and chronic conditions in early childhood. Women also have an increased risk of postpartum depression in such conditions. For senior citizens, risk of neurodegenerative diseases and osteoporosis increase significantly.

Air Pollution: What Is It and What Does It Mean for Cities? |Topos Magazine

Industry and Mortality Gap

From 2023 to 2024, the American Lung Association (ALA) reported an 11.7 million increase in Americans exposed to unhealthy air environments. In 2019, the WHO estimated that 4.2 million premature deaths were caused by air pollution, making it the second-highest risk factor for noncommunicable chronic illness. Yet, recent studies show a disparity between healthcare professionals' understanding and training on the issue.

Notable Federal Regulations

Clean Air Act (CAA) - 1970 (and Amendments in 1977, 1990)
* Foundation of federal air pollution regulation.
* Authorizes EPA to set National Ambient Air Quality Standards (NAAQS) for key pollutants.
* Regulates emissions from stationary sources (factories, power plants) and mobile sources (cars, trucks).
* Introduced permitting programs for major sources.
* Established enforcement mechanisms and citizen suits.

National Ambient Air Quality Standards (NAAQS)
* Set limits for six “criteria pollutants”: ozone, particulate matter (PM2.5 and PM10), carbon monoxide, nitrogen dioxide, sulfur dioxide, and lead.
* States must develop State Implementation Plans (SIPs) to meet these standards.

National Emission Standards for Hazardous Air Pollutants (NESHAP)
* Controls emissions of toxic air pollutants from specific sources.

* Focus on pollutants causing serious health effects (e.g., benzene, asbestos).

Greenhouse Gas (GHG) Regulations
* EPA authority to regulate GHGs under Clean Air Act (e.g., vehicle emissions standards, power plant emissions).
* Includes programs like the Clean Power Plan (though contested).

For more statistics and information on disease severity and scope, read here.

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