As of 10 AM this morning the Air Quality monitors in Pima County are measuring Unhealthy levels of small particulate matter in the air at some locations.
Unhealthy is the highest and worst ranking category in the Air Quality Index.
According to the AirInfoNow.org Unhealthy levels mean "increased aggravation of heart or lung disease and premature mortality in persons with cardiopulmonary disease and the elderly; increased respiratory effects in general population."
Stay inside if you suffer from severe asthma or other respiratory problems.
The website lists small particulate matter as toxic organic compounds and heavy metals.
These are created by driving automobiles, burning plants (brush fires or yard waste), and metal processing at smelters or mines.