How Is Air Quality Measured?

Smog. Pollen. Wildfire smoke. Even something as simple as breathing can be complicated by outside forces. How do we measure changes to the air we breathe to survive? The air quality index was created by the U.S. Environmental Protection Agency to communicate whether the air quality and air pollution level in an area is healthy or unhealthy. The EPA updates U.S. maps every 8 or 24 hours with information on current air conditions. Countries around the world use the AQI to communicate air quality conditions to their citizens. Air quality is monitored for six pollutants:
particulate matter
ground-level ozone
sulfur dioxide
nitrogen dioxide
carbon monoxide
and lead. The AQI is calculated using a standardized rubric of air pollutant levels. An AQI of 0–50 is considered “green,” or satisfactory. The air poses little to no risk to those breathing it. An AQI of 301 or higher, however, is considered “maroon”: emergency conditions where everyone is more likely to be affected. Any AQI over 100 is considered unhealthy. High levels of air pollution are especially harmful for people in certain groups, including children, those over 65, and people with asthma. Chronic exposure to air pollution, though, is harmful for everyone. It carries an increased risk for chronic diseases and even cancer.