Air quality is increasingly recognized as a "social determinant of health": a condition determined by the community in which one lives that is external to an individual person's control but has an impact on their health and well-being.

In 2019, 65% of days in Lancaster were healthy air days, slightly above 64% in 2000. The year with the fewest healthy air days was 2014, at 34%. Lancaster lags behind its peer counties in air quality: in 2019, Chester and Cumberland had 73% of their days with good air quality, Berks had 76%, Lebanon had 77%, Dauphin had 78% and York had 82%. The air quality of York, Lebanon, Dauphin, Cumberland and Berks have all increased by significant amounts since 2000.

Comparable national and state data is not available due to the quantity and location of EPA monitoring stations. Exposure to these pollutants can cause short-term health effects such as irritation to the eyes, nose and throat, coughing, sneezing, runny nose, and shortness of breath. Continued exposure can also worsen medical conditions such as asthma and heart disease. Data for this indicator are expected to be released annually in July.