Air Quality

Air Quality

Ground Level Ozone

  • Ozone is created when nitrogen oxide (NOx) and volatile organic compounds (VOCs) react with sunlight and heat. A substantial amount of these precursor emissions are generated in Central Texas – primarily from trucks, automobiles and construction vehicles.
  • In 2008 the EPA lowered the ozone design value from 84 parts per million (ppm) to 75 ppm. The Austin region was able to reach attainment according to the new standard in 2009.

Ground Level Ozone

Air Emissions

  • The EPA Toxic Release Inventory (TRI) tracks emissions and waste generation from industrial processes. Most of the on-site emissions (off-site emissions indicate waste moved for disposal somewhere else) are released to the air, primarily through controlled stacks.
  • Air releases in Bastrop County are related to brick manufacturing; in Hays County air releases are related to cement manufacture.

Air Emissions

Ozone Action Days

  • About 73% of Central Texans are familiar with Ozone Action Days – a public awareness and personal action campaign triggered when conditions are predicted to be ideal to generate ground level ozone at levels harmful to human health.
  • In 2010, respondents from all counties indicated a lower awareness than in 2008, a year in which more stringent attainment standards were introduced.
Ozone Action Days

Survey Question: Are you familiar with Ozone Action Days?

Action on Ozone Action Days

  • Almost 35% of Central Texans report taking two actions that have been shown to reduce local emissions that contribute to ozone generation. However, in 2010, behavioral changes were generally less frequent than they were in 2008.
  • More than 20% of Central Texans do nothing different on Ozone Action Days – another 15% make no changes in their commuting pattern.
Action on Ozono Action Days

Survey Question: Do you do any of the following differently on Ozone Action Days?

Perception of Ozone

  • About 65% of Central Texans perceive high ozone levels as a “somewhat” or “very” serious threat to themselves and their family.
  • About 13% perceive no threat from high ozone levels.
  • While political affiliation continues to show a correlation with the perceived seriousness of environmental threats, most respondents from both parties agree that the threat is at least “somewhat” serious.
Perception of Ozone

Survey Question: What threat do you believe higher ozone levels pose to you and your family?


While air quality is steadily improving in Central Texas, the urgency to maintain efforts remains high.


Central Texans are not exposed to levels of air pollutants that are hazardous to their health or the environment.


Regional air quality is determined by multiple activities, some of which we can manage through local policy and personal choices – such as local pollution emissions, efficient mobility and land use coordination, public awareness – and some which we cannot – such as continental weather patterns and non-local emissions.


Indoor Air Quality


The EPA ozone “design value” is calculated with the fourth highest annual daily maximum eight-hour ozone concentrations averaged over a three-year period. The Austin area currently measures ozone concentrations at three monitors.

Texas Commission on Env. Quality

U.S. Environmental Protection Agency

CTSIP Community Survey