How can Mecklenburg County meet federal health-based air quality standards at the same time the American Lung Association’s (ALA) 2026 State of the Air report gives the County a failing grade?
The answer lies in the methodology that ALA, an advocacy organization, uses to assign grades. You’ll see that it is different than how air quality agencies determine regulatory compliance with the official national health standards.
How the American Lung Association Calculates Its Grades
ALA methodology uses a weighted, 3-year average of the number of poor air quality days (i.e. orange, red, and purple days) to determine a letter grade:
- A = 0.0 days/year
- B = 0.3-0.9 days/year
- C = 1.0-2.0 days/year
- D = 2.1-3.2 days/year
- F = 3.3+ days/year
Areas receive a failing grade if they average 3.3 or more days poor air quality days per year. That means that Charlotte’s average of 3.7 days/year is graded with a “F.” Los Angeles’s average of 119 days/year also equates to an F.
Air Quality in Mecklenburg County
The ALA State of the Air report is one way to evaluate air quality. The U.S. Environmental Protection Agency evaluates air quality using a different set of standards. Despite receiving failing grades under ALA’s grading methodology, metro cities like Charlotte/Mecklenburg have seen consistent and sustained air quality improvements over time. In 2025, Mecklenburg County celebrated a decade of compliance with all federal health-based standards, including those set for ozone and particle pollution (particulate matter).
Compliance with federal health-based standards is based on pollution concentrations rather than the average number of poor air quality days. Pollution concentration can be compared year to year to track progress.
365 Days of Healthy Air
Mecklenburg County reached a new milestone in 2025: 365 days of clean air, the first year on record with zero unhealthy air quality days. This milestone was made possible thanks to sustained air pollution reduction from sources in the county and the region, favorable weather conditions, and limited impacts from uncontrolled wildfires or prescribed burns.
Mecklenburg County Air Quality’s team of environmental professionals continue to improve our air by:
- Measuring air pollution and making quality-assured data available to the public and decision makers.
- Improving air quality by ensuring compliance with air pollution rules and implementing local programs that reduce air pollution.
- Listening to community input and responding with programs and resources that meet residents’ needs.
Learn more about the Air Quality team and their work.