What is the difference between health advisories and air action days (“burn days”)?
The air quality standard (35 ug/m3) is the threshold set by the EPA that requires states to impose certain pollution control regulations if exceeded. When pollution levels are between 25 and 35 ug/m3, a “yellow” air action alert is issued to encourage people to keep pollution levels below the standard. A “red” air action alert is issued when pollution levels are higher than the standard. Health advisories provide the public with precautionary steps that may need to be taken if air pollution levels rise above the health standard. Health advisories fall into five categories according to worsening levels of pollution. As the pollution level increases, the health advisories become more restrictive in limiting prolonged or heavy exertion outdoors.
