Air Quality and Health


Key Takeaways

  • Local air quality impacts health and quality of life
  • The Air Quality Index (AQI) is used to report daily local air quality
  • Particle and Ozone pollution have some of the greatest impacts on local air quality
  • Poor air quality can trigger health effects such as asthma, heart attacks, and stroke
  • Children, older adults, and people with diseases of the heart and lungs are sensitive groups considered to be at high risk for health impacts related to poor air quality

Take step to protect your health

There are many sources of air pollution in Harris County and Harris County experiences many days each year that are a health concern for those most at risk. Take these steps to protect your health.

Check the AQI forecast

Harris county was given an “F” grade for ozone levels from the American Lung Association. In 2020, the annual level of PM2.5 in Harris County was 11.6µg/m3., just slightly better than the national standard of 12.0µg/m3. Use AQI forecasts to plan outdoor activities.

On days with an unhealthy AQI Forecast

  • Choose a less-strenuous activity
  • Shorten your outdoor activities
  • Reschedule activities
Sign up for Air Quality Alerts
  • For people with asthma  consider registering for AlertHouston Asthma Air Aware warnings via email, text and/or voice call.
Protect yourself

There are nearly 12,000 ER visits and 20 deaths from asthma each year in Houston. Boys (especially younger than 10 years old) and African Americans are more likely to be hospitalized

  • Avoid outdoor activities near high traffic roadways
  • Wear a dust mask when mowing grass and doing yard work
Take steps to reduce air pollution
  • Walk or bike on clean air days
  • Carpool or take public transit
  • Turn off your car in school pick-up and drop off lines


Who is Impacted?

The graphic below depicts specific populations that may be more sensitive to air pollution and at greater risk for health impacts. For more information about at-risk populations and communities visit the air quality and health vulnerability assessment.


Common Air Pollutants

There are many chemicals and compounds that can pollute the air. The Clean Air Act requires the EPA to determine National Ambient Air Quality Standards (NAAQS) for six common air pollutants.

  • Particle Pollution (PM2.5 and PM10)
  • Ground-level ozone
  • Carbon Monoxide
  • Lead
  • Sulfur Dioxide
  • Nitrogen Dioxide
Particulate Pollution

Particle pollution comes from many different sources. Fine particles (2.5 micrometers in diameter and smaller) come from power plants, industrial processes, vehicle tailpipes, woodstoves, and wildfires. Coarse particles (between 2.5 and 10 micrometers) come from crushing and grinding operations, road dust, and some agricultural operations. (source:

Why is particle pollution a problem? Particle pollution is linked to several health problems, including coughing, wheezing, reduced lung function, asthma attacks, heart attacks and strokes. It also is linked to early death. (source:

Ozone Pollution

Ozone is a colorless gas that can be good or bad, depending on where it is. Ozone in the stratosphere is good because it shields the earth from the sun’s ultraviolet rays. Ozone at ground level, where we breathe, is bad because it impacts harm human health.

Ozone forms when two types of pollutants (VOCs and NOx) react in sunlight. These pollutants come from sources such as vehicles, industries, power plants, and products such as solvents and paints.

Why is ozone a problem? Ground -level Ozone can cause several health problems, including coughing, breathing difficulty, and lung damage. Exposure to ozone can make the lungs more susceptible to infection, aggravate lung diseases, increase the frequency of asthma attacks, and increase the risk of early death from heart or lung disease. (source:


Volatile organic Compounds (VOCs) are chemicals that evaporate easily into the air at room temperature. There are many VOCs and many different sources. Benzene, chloroform, formaldehyde, isoprene, and methanol are just a few examples. VOCs may come from natural sources such as oak and maple trees, as well as human-made sources such as industrial solvents, power generation, and motor vehicles.

Why are VOCs a problem? Like Ozone and Particulate Matter, VOCs cause respiratory issues. Additionally, they may cause headaches and cancer. VOCs also react with Nitrogen Oxides (NOx) to form ground level ozone.