Reason for Ranking
The relationship between elevated air pollution (especially fine particulate matter and ozone) and compromised health has been well documented.[1,2] Negative consequences of ambient air pollution include decreased lung function, chronic bronchitis, asthma, and other adverse pulmonary effects.
Measurement Strengths and Limitations
While this measure estimates the average annual concentration of fine particulate pollution in the county, it can miss important short-term fluctuations in air quality (such as stagnation events), local patterns (high concentrations near roads and other major sources), and other pollutants (such as ozone, etc.). Even within counties with low average fine particulate matter concentrations, locations can experience days of dangerously elevated levels, which can place individuals at risk for serious cardiovascular problems. It should be noted that these data are derived from only one air quality model among several. Like all models, this air quality model has errors. For data that utilize a different underlying model, please see the CDC Wonder Environmental data. Both of these models produce smoothed estimates of air quality that may obscure local conditions. You might also consider contacting air quality experts in your state who will have more detailed knowledge of within-county differences in air quality.