Air Quality Index in Chicago, IL

Common pollutants that affect the air quality index in Chicago include ground-level ozone (O3), which forms when sunlight reacts with vehicle exhaust, industrial emissions, and other pollutants. Particulate matter (PM2.5 and PM10) also contributes to poor air quality, coming from vehicles, construction, and industrial activities. Nitrogen dioxide (NO2), mostly from car emissions and power plants, plays a role in forming ozone and particulate pollution. Carbon monoxide (CO), which comes from cars and industries, can lower air quality and impact health. Volatile organic compounds (VOCs) from vehicles and factories also contribute to ozone formation.

The air quality index in Chicago is usually the worst during the summer months, from May to September. This is when high temperatures and sunlight cause an increase in ground-level ozone, which is a major contributor to air pollution. Air quality can also worsen during periods of stagnant weather with little wind, trapping pollutants in the air. Additionally, wildfires in the region or nearby areas can add particulate matter to the air, further lowering the AQI, especially in late summer and fall.

Some areas in Chicago tend to have better air quality, typically due to more green spaces and less traffic. Neighborhoods like Lincoln Park, Hyde Park, and areas near the lakefront often have cleaner air because of the abundance of parks and the natural air filtration provided by trees and water. Additionally, neighborhoods farther from major highways and industrial zones, such as the North Side, can experience better air quality.