What is the Air Quality Index? part 1

Depending on where you live, your age, sensitivity to airborne constituents and other factors, the air quality index (AQI) could be something that you monitor frequently.

In the U.S., the AQI developed by the Environmental Protection Agency (EPA) is a nationally uniform color-coded index for reporting air quality. Air agencies use the AQI report and forecast daily air quality. In addition to the color code, the AQI reports the most common ambient air pollutants that are regulated under the Clean Air Act, including ozone and particle pollution (PM₁₀ and PM_2.5). Further, it identifies who may be affected and provides steps to take to reduce exposure when pollution levels are unhealthy.

With values from 0 to 500, the normalized AQI scale provides a means to quickly and easily identify increasingly unhealthy readings. As shown in Table 1, AQI values above 100 indicate unhealthy air quality, at first for sensitive groups at the greatest risk of health problems, then for the entire population as AQI values increase.

 

 

 

 

 

 

 

Table1. Components of the AQI include: the AQI categories and colors, corresponding index values and cautionary statements for different levels of health concern.

It is important to note that allergy levels are measured and reported separately from the AQI. For allergies, airborne biological particles are usually monitored by particle impaction (surface collection) and microscopic examination. In this case, different monitoring stations provide regional-scale measurements for aeroallergen (airborne substances that cause allergies) levels.

With the ongoing 2020 wildfire season in California or intense heat (≥110°F and subsequent ozone levels) in Arizona, sensitive residents in these areas need to check their local AQI daily. Part 2 of this blog will address different techniques that can cause discrepancies in readings and interpretation.