Putting Houston's Air Quality in Context

The Federal Government has established six National Ambient Air Quality Standards. Houston's air meets five of the six NAAQS. The one standard that Houston is still working to attain is ground-level ozone. For more information about he NAAQS, visit the EPA's website: http://www.epa.gov/air/urbanair/6poll.html

The quality of Houston's air compares favorably with other cities when looking at all the NAAQS. According to EPA data, Lost Angeles, Phoenix, New York, Pittsburgh, El Paso, Chicago, Greater Connecticut, Denver, Las Vegas, Salt Lake City and St. Louis fail to meet two or more of the NAAQS.

• Peak ozone levels declined by 20 percent;
• The maximum number of days in which ozone exceeded the one-hour NAAQS at any single monitoring site declined by more than 50 percent;
• The maximum number of hours that a single monitoring site measured ozone values above the one-hour NAAQS annually declined by 80 percent;
• In 2005, ozone levels were above the one-hour ozone NAAQS for a maximum of 17 hours at an individual air monitor (e.g., below the NAAQS for 99.8% of the time);
• Median levels of other Criteria Pollutants (e.g., sulfur dioxide, nitrogen dioxide, and carbon monoxide) have not increased (some medians are declining) despite increases in population, vehicle traffic, and industrial activity;
• Since 1988, measured levels of key indicator Volatile Organic Compounds (VOCs) (e.g., benzene) in the Houston Ship Channel declined on average by over 80 percent;
• Since 1983, the eight-hour ozone design value decreased by 41 ppb.

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Effects Screening Levels

• ESLs are established by TCEQ based on data concerning health effects, odor, nuisance potential, vegetation impacts, and corrosion effects
• ESLs are not ambient air standards, but are primarily used by TCEQ in evaluating applications for air permits
• Concentrations at or below the ESLs indicate no adverse health or welfare effects are expected
• Concentrations above the ESLs do not necessarily indicate a health effects problem, but trigger a more in-depth permit review

• Almost all monitored VOCs are below their annual ESL; most are a small fraction of their annual ESL
• The one exception is the level of benezene at one monitoring site. Across the network, more than 99 percent of the benzene readings are below the 24-hour ESL. Overall, benzene levels have decreased about 80 percent over the past 15 years
• Benzene levels in Houston are comparable to other US cities

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Our Mission Going Forward:
Maintaining and Improving Air Quality

Our on-going mission is to provide data to member companies to enable them to meet state and federal air standards. By using HRM data, our member companies can identify air control improvement projects.

Our member companies are working with the Texas Commission for Environmental Quality to take advantage of HRM member companies working with TCEQ the Environmental Monitoring and Response System (EMRS) pilot program. This voluntary effort began in June 2004. Through the pilot, we're testing a web-based notification system that allows real time response to high ambient Highly Reactive VOCs levels. HRM is funding three of the seven monitors and the industry notification system

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