Air Quality

This indicator looks at the number of good or poor air quality days. Air quality is determined by the levels of contaminants in the air. This is important because clean air is essential for a healthy population and natural environment. The recent increasing occurrence of wildfires in Washington has increased the levels of air contaminants, negatively impacted the quality of air, and led to an uptick in health issues. In addition, the negative effects of bad air quality is not shared equally. Communities might experience bad air quality differently, especially if they are more vulnerable.

Key Findings

The number of good air quality days in Washington was on a downward trend from 2019 to 2022. However, the number of good air quality days increased in 2023, returning to a high of 319 days.

There is a wide variation of air quality across counties. In 2024, Skagit county had close to a full year of good air quality days, while Asotin county had around 61% of good air quality days.

Methodology

Air quality days are categorized as either good or bad. This means days with Moderate, Unhealthy for Sensitive Populations, Unhealthy, Very Unhealthy, and Hazardous are all classified as bad air quality days. Days with Good air quality are categorized as good air quality days.

Data Quality & Limitation

There are geographical limitations on measuring air quality since air monitoring stations are concentrated in certain areas. In addition, there was inadequate data for a number of counties between 2019 and 2023.

Counties with less than 90% of valid data days in a year were excluded from the composite score calculation to ensure data reliability.

Definition