Data provided by
|3||Haden Road 2|
|5||Haden Road 3|
|6||Monarch Oaks Street|
|7||AAH - Central Business District|
|10||Washington Avenue Coalition / Memorial Park|
(local time)SEE WORLD AQI RANKING
live AQI index
|Air pollution level||Air quality index||Main pollutant|
|Moderate||55 US AQI||PM2.5|
|Close your windows to avoid dirty outdoor air|
|Sensitive groups should reduce outdoor exercise|
|Saturday, Aug 1|
Good36 US AQI
|Sunday, Aug 2|
Good45 US AQI
|Monday, Aug 3|
Good46 US AQI
Good40 US AQI
|Wednesday, Aug 5|
Good38 US AQI
|Thursday, Aug 6|
Good42 US AQI
|Friday, Aug 7|
Good40 US AQI
|Saturday, Aug 8|
Good28 US AQI
|Sunday, Aug 9|
Good41 US AQI
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In recent years, Houston’s average annual air quality has met the US Environmental Protection Agency (EPA) qualification for “good,” indicating that the air generally poses little risk to health. Since annual averages smooth over elevated periods of pollution, they can fail to portray potential risks accurately. Despite an annual “good” air quality index, there have been a number of unhealthy pollution days in recent years which have caused Houston to continually fail to meet federal attainment levels for daily ozone and PM2.5.
An air quality index (AQI) value is calculated by weighting six criteria pollutants for their risk to health in a formula. Fine particulate matter (PM2.5) and ozone are weighted more heavily for their high risk to human health, and as a result, PM2.5 and ozone most often determine overall AQI.
PM2.5 is fine airborne particulate matter measuring 2.5 micrograms or smaller. Due to its microscopic size, PM2.5 is able to penetrate deep into the lungs and then into the bloodstream, potentially causing a wide range of short- and long-term health effects. Exposure to PM2.5 has been directly linked to conditions such as heart and lung disease and early death.
In 2019, Houston exceeded the PM2.5 recommendation set forth by the World Health Organization (10 μg/m3) by 0.8 μg/m3. November (14.8 μg/m3), December (13 μg/m3), and March (12.7 μg/m3) experienced particle pollution levels defined as US AQI “moderate” – air that poses some risk to sensitive groups, including children, the elderly, and people with pre-existing cardiovascular or respiratory health conditions.
An analysis conducted by the Environmental Defense Fund and the Harvard School of Public Health estimated that Houston’s PM2.5 pollution has contributed to more than 5,000 early deaths and $49 billion in economic damages in 2015 alone.1 Such high annual costs highlight a need to further tighten PM2.5 standards. A study conducted by the US EPA revealed that reducing the federal limit for annual PM2.5 from 12 μg/m3 to 9 μg/m3 could save as many as 12,150 lives a year.2 In Houston, it is evident more stringent standards are needed. 75 percent of the health burden is carried by communities who already exceed the current federal PM2.5 standard.
Ozone is a gaseous pollutant and component of smog formed in the atmosphere when sunlight causes nitrogen oxides and organic substances to react. Like PM2.5, ozone can also cause respiratory infections, inflammation, and early death.
According to the 2019 State of the Air report by the American Lung Association, Houston ranks 9th nationally for worst ozone pollution with a weighted average of 26.7 days annually exceeding standards.3 That’s nearly a month of dangerous ozone levels per year.
Houston’s relatively high average temperatures, abundant sunshine, large oil and energy industry and dispersed population make it challenging for the city to reach attainment levels. The city has never, in fact, met daily attainment levels for ozone.
Air quality data changes hourly, based on emissions and weather. Check real-time air quality levels in Houston at the top of this page and follow Houston’s forecast air quality data to take proactive steps in reducing exposure to unhealthy air.
Like much of the United States, Houston’s air pollution has improved over recent decades as a result of increasingly stringent regulations on a wide variety of industries. Just twenty years ago, Houston often swapped ‘most polluted’ titles with Los Angeles. Today, Houston’s air quality is much improved, though still relatively high compared to the US average. According to the 2019 World Air Quality Report, Houston ranks 244th out of 1517 included cities for highest PM2.5. Moreover, the city has seen a recent rise in both PM2.5 and ozone pollution since at least 2017.
For fine particulate matter, or PM2.5, Houston experienced a 7.8% increase from 2017 to 2018, and another 11.3% increase from 2018 to 2019. These increases, though subtle, show a concerning trend. But a steadily growing population and economy does not need to be a reason for more emissions. Shifting towards cleaner energy and more fuel-efficient low emission vehicles are two impactful ways to greatly reduce Houston’s air pollution levels.
For ozone, Houston experienced its highest record from 1997 to 1999, when there was a weighted average of 110 unhealthy air days. This number has fallen dramatically since, yet the most recent average of 26.7 days is still nearly 8 times the US EPA attainment limit.
‘Stay-at-home’ measures implemented during the 2020 COVID-19 pandemic have resulted in some city-wide pollution reductions, including a 13% drop in ozone.4 As the economy opened back up, movement and industry quickly returned to ‘normal’ levels, with pollution reductions just as quickly diminishing.
Houston’s unhealthy air quality is primarily attributable to ozone pollution. Warm urban climates are naturally predisposed to higher ozone levels because they provide ideal environmental conditions for ozone formation, such as sunshine, heat, and abundant precursor pollutants.
Like most big cities, air pollution seems an inevitable byproduct of the area’s population and economy. There are 7 million people, 5 million registered vehicles, and 121,000 industrial businesses in the greater Houston area. The Port of Houston is one of the nation's busiest, producing 4.1 tons of smog-forming pollution each year.5
In addition to these emission contributors, global warming is expected to exacerbate ozone levels by providing warmer temperatures ideal for ozone formation.
60 percent of Houston’s ozone pollution is estimated to result from vehicle exhaust alone. During the COVID-19 pandemic, ‘stay-at-home’ measures are likely to have contributed to the city’s improved air quality by keeping cars off the road in significant numbers. Houston saw a 13% reduction in ozone during this time. While short-term, these improvements shed light on what is possible by transitioning residents to more fuel-efficient, low-emission vehicles and investing in mass public transit.
Higher density areas tend to have higher pollution levels. Downtown Houston AQI, for example, tends to be much higher than the greater Houston area. Use the air pollution map of Houston to understand local variances across the city.
+ Article Resources
 Roy A. (2020, May 11). Amid COVID-19, the Trump administration sets dangerous air pollution standards. What is at stake for Houstonians? Environmental Defense Fund.
 Environmental Protection Agency. (2019). Policy assessment for the review of the national ambient air quality standards for particulate matter, external review.
 American Lung Association. (2019). State of the Air – 2019.
 Rogalski J. (April 10, 2020). A side effect of COVID-19 crisis: Houston's air is cleaner. WQAD 8.
 Environmental Defense Fund. (2020). Cleaner air in port cities.