Residents in Yuma, Arizona , have been urged to stay indoors and reduce activity levels after a hazardous air quality warning was issued by the Environmental Protection Agency (EPA) through the AirNow service. The area has been placed under a critical air quality alert because of elevated levels of particulate matter (PM). The primary pollutant involved is PM10, which has reached an alarming Air Quality Index (AQI) reading of 961, far surpassing safe levels. The EPA advises that everyone,