|3||Seeley Lake, Montana|
|4||Klamath Falls, Oregon|
|5||Hot Sulphur Springs, Colorado|
|6||Peaceful Valley, Washington|
|8||Tuolumne City, California|
(local time)SEE WORLD AQI RANKING
8:01, Mar 3
live AQI index
|Air pollution level||Air quality index||Main pollutant|
|Good|| 27 US AQI||PM2.5|
|PM2.5|| 6.6 µg/m³|
|o3|| 27.2 µg/m³|
|Open your windows to bring clean, fresh air indoors|
|Enjoy outdoor activities|
|Saturday, Feb 27|
Good 43 US AQI
|Sunday, Feb 28|
Good 32 US AQI
|Monday, Mar 1|
Good 14 US AQI
|Tuesday, Mar 2|
Good 23 US AQI
Moderate 57 US AQI
|Thursday, Mar 4|
Moderate 65 US AQI
|Friday, Mar 5|
Good 33 US AQI
|Saturday, Mar 6|
Moderate 69 US AQI
|Sunday, Mar 7|
Moderate 78 US AQI
|Monday, Mar 8|
Moderate 62 US AQI
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Washington DC’s air quality suffers from high ozone levels, which exceed government standards. The city, however, meets federal attainment for all other key criteria pollutants monitored by the US Environmental Protection Agency (EPA): PM2.5, PM10, CO, SO2, and NO2.
Ozone is an invisible, highly reactive gas molecule composed of three oxygen atoms. Rather than being directly emitted into our air by industrial activity, motor engines, or various sources of combustion, like other criteria pollutants, ozone is formed in our atmosphere from airborne hydrocarbons and nitrogen oxides reacting in sunlight. This property of forming from precursor pollutants in the air rather than ground-based activity makes ozone difficult to manage. Precursor pollutants may originate from local emission sources or flow into a city from up to a thousand miles away.
Breathing ozone pollution can cause serious health complications, ranging from a cough and breathing problems to respiratory infections, cardiovascular effects, and premature death.
The District of Columbia has failed to meet ozone attainment levels since at least 1996.1 Several years ago, the city got close, however, with a weighted average of 3.3 unhealthy ozone days from 2014-2016, just slightly above the 3.2-daylimit for unhealthy days. Since this period, Washington DC’s ozone levels have been on the rise. From 2016 to 2018, the most recent monitoring period, the city experienced 5.2 unhealthy ozone days. These days in excess of safe ozone levels have landed the city an “F” rating for ozone levels since tracking began.
A study conducted by the Ozone Transport Commission estimated that roughly 24,448 residents experienced acute respiratory symptoms in 2018 as a result of high ozone levels, while 19 were admitted to the hospital for severe symptoms.2 Warming temperatures as a result of climate change are expected to increase ozone levels as a result of hotter, more ideal conditions for ozone formation. To combat this, increased regulation on heavy duty trucks and vehicles as well as improved regional cooperation with nearby Virginia and Maryland is critical to further reducing ozone levels in the future in the wake of rising temperatures.
Fine particulate matter, or PM2.5, is another closely monitored and actively managed pollutant in Washington DC. PM2.5 describes any airborne particulate matter smaller than 2.5 microns in size, including a wide range of chemical makeups and sources. Its near microscopic size enables PM2.5 to be inhaled deep into the lungs and often into the bloodstream. This property contributes to PM2.5’s far reaching health implications, including short-term effects like coughing, wheezing, shortness of breath, and aggravated asthma as well as long-term effects like lung damage and decreased lung function, cancer, and premature mortality.3
Though Washington DC has met federal attainment levels for annual and 24-hour PM2.5 since 2009, pollution events are not uncommon, particularly during the winter months. December, January, and February are often Washington DC’s most polluted months for PM2.5. During these months, increased emissions from home and building heating can become trapped by temperature inversions, a weather event in which a hot layer of air traps cooler, more polluted ground-level air from rising and dispersing. In 2017, October, November and December all experienced average PM2.5 levels in the “moderate” US AQI category, outside of the federal target.
Follow live air quality data in Washington DC at the top of this page and on the IQAir air pollution app. Use the District of Colombia forecast air quality data to plan ahead and take precautionary measures to reduce your pollution exposure.
From a long-term perspective, air quality in Washington DC has seen drastic improvements over recent decades. Data from the EPA National Emissions Inventory (NEI) estimates that emissions of all criteria pollutants and their precursors have gradually fallen since 1996. These reductions come despite increases in population, employment, and households, suggesting that actions taken to control Washington DC’s air pollution have generally been successful.
Air quality levels in Washington DC are notably lower than neighboring cities. This has been true for ozone levels since 2002 and PM2.5 levels since 2008.2 Air pollution levels in nearby Baltimore, for example, are consistently worse, on average, than Washington DC. Polluted air blown from Maryland and Virginia contribute significant amounts of pollution to the DC area. Cooperating with neighboring states to implement further legislation on emissions presents an opportunity for further reducing air pollution in the District.
Air quality levels in Washington DC fell by 10 to 20 percent during the 2020 COVID-19 lockdown compared to the same time period a year prior in 2019.4 City lockdown measures shuttered nonessential businesses and resulted in greatly reduced traffic congestion, as residents tended to avoid non-essential travel. These reductions highlight what could be achieved through transitioning residents to greener transport options and more fuel efficient, lower-emission vehicles.
In recent years, Washington DC has taken steps to improve the attractiveness and accessibility of green transport options like walking and biking, which reduce car traffic and lead to cleaner air in the district. This strategy has included adding many more miles of bike lanes, instituting “slow streets” that limit vehicle speeds to 15 mph, and growing the network of city sidewalks.
Washington unhealthy air quality is the result of elevated ozone levels. As an urban area with relatively little industry, the majority of Washington DC air pollution comes from vehicular emissions and emissions blowing in from neighboring cities and states.
Nearly half of Washington DC air pollution originates from mobile sources: cars, trucks, trains, and planes. On-the-road mobile emissions are the largest source of the ozone precursor nitrogen dioxide (NOx) and the second largest source of the ozone precursor volatile organic compounds (VOCs).2
Regionally, most precursor pollutants for ozone formation originate in the areas surrounding Washington DC. Maryland is estimated to contribute to 52% of the region’s VOCs and 47% of the regions NOx, while Virgiana contributes 43% of the VOCs and 45% of the NOx. Washington DC, on the other hand, is estimated to only contribute 5% of the region’s VOCs and 8% of the regions NOx.
Washington DC AQI can vary from location to location, even within the city. Use the Washington DC air pollution map to understand the flow of emissions from neighboring cities and local sources.
+ Article Resources
 American Lung Association. (2019). State of the air – 2019.
 Monitoring and Assessment Branch Air Quality Division Department of Energy and Environment. (2020). Ambient air quality trends report, 1996-2019.
 World Health Organization. (2020). Air quality guidelines – global update 2005.
 Goffman E. (2020, June 29). DC has cleaner air now. But as reopening plans continue, how can it keep the pollution at bay?
Data sources 4