Summers 2004-2009

2009
The 2009 Ozone season was defined by its exceptionally good air quality in the Washington DC region, with over 97% of all days having either Code Green (good) or Code Yellow (moderate) air quaility. More importantly, the region did not have a single Code Red (unhealthy for all) air quality day.

2008
Over the course of the 2008 Ozone season (151 days), the Metropolitan Washington Council of Governments (COG) data shows that 89 percent of the days had Code Green (good) or Code Yellow (moderate) air quality.

Throughout the season our region had 14 Code Orange (unhealthy for sensitive groups) days, three days registered Code Red (unhealthy for all) and zero days registered Code Purple (very unhealthy for all).

2007

The region's air quality continued to improve during the 2007 Ozone Season (May 1 to September 30). The Metropolitan Washington Council of Governments (COG) data shows almost 90 percent of the days had Code Green (good) or Code Yellow (moderate) air quality, with only one code red day all summer.

Code Green (Good) – 60 days (39%)

Code Yellow (Moderate) – 77 days (50%)

Code Orange (Unhealthy for Sensitive Groups) – 16 days (10.5%)

Code Red (Unhealthy) – 1 day (.5%)

Code Purple - (Very Unhealthy Air Quality) - 0 days (0%) 

2006
For the 2006 Ozone Season (May 1 to September 15) the Metropolitan Washington Council of Governments (COG) data shows almost 90 percent of the days had Code Green (good) or Code Yellow (moderate) air quality.

Code Green (Good) – 69 days (50%)

Code Yellow (Moderate) – 50 days (36%)

Code Orange (Unhealthy for Sensitive Groups) – 16 days (12%)

Code Red (Unhealthy) – 1 day (1%)

Code Purple - (Very Unhealthy Air Quality) - 1 days (1%)

2005
Despite tougher 8 hour federal standards and a particularly hot August, no code red days occurred in 2005. 87% of the days had moderate or good air quality.

Code Green (Good) – 74 days (54%)

Code Yellow (Moderate) – 45 days (33%)

Code Orange (Unhealthy for Sensitive Groups) – 19 days (13%)

Code Red (Unhealthy) – 0 days (0%)

2004
Ozone Season (May 1 to September 15) most days had good air or only moderate pollution under the one-hour standard in effect at that time.

Code Green (Good) – 93 days (67%)

Code Yellow (Moderate) – 38 days (28%)

Code Orange (Unhealthy for Sensitive Groups) – 5 days (4%)

Code Red (Unhealthy) – 2 days (1%)

99% of the summer’s Ozone Season days met the One-Hour Standard.

The Code Red day on July 2nd occurred because it was a very hot day with very little wind. Still 14 of the 17 regional monitors registered no violations.

July 3rd’s Code Red day resulted from the ozone that was left over from July 2nd.