Code Orange Air Quality alert for the D.C. region today (EPA AirNow) Code Orange Air Quality alert for the D.C. region today (EPA AirNow)

The hot, stagnant air over the Washington, D.C. area has prompted the first air quality alert of 2013.

The alert level is code orange, which indicates the air is unhealthy for sensitive groups, referring to older adults, children, and people with respiratory ailments like asthma and lung disease.  These groups are encouraged to minimize strenuous activity outdoors.

Code orange alerts are fairly common over the D.C. area in summer; 19 such days occurred in 2011 and 16 in 2012.  Code red alert days, which indicate the air is unhealthy for all groups, are more rare and have a frequency of just one or two days per summer (on average).

The American Lung Association ranked D.C. the 9th worst metropolitan area for ozone air pollution in its 2013 State of the Air report, assigning it a grade of F (on an A-F scale).

On the plus side, air quality has improved in the region over the years thanks to pollution controls. The number of combined code orange and red days has declined markedly since the mid-1990s according to the American Lung Association report.  In 1996, there were 22 more bad (orange or red) air quality days than in 2011 the report said.

AAA Mid-Atlantic noted the number of overall ozone exceedance days in 2012 dropped for the third straight year despite scorching temperatures.