What We Know

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 the NAAQS, visit the EPA's website: http://www.epa.gov/air/criteria.html

Houston’s air quality compares favorably with many other large cities, with the area attaining five of the six standards. For comparison, Los Angeles, Washington D.C., Chicago, New York, Philadelphia, Phoenix, Sacramento, and Salt Lake City only meet four or fewer of the six air quality standards.

Through concerted effort and investment, Houston has achieved an 87 percent reduction in the ambient concentrations of  key Volatile Organic Compounds (Benzene, Toluene, Ethylbenzene and Xylenes)  in the past 27 years. While great strides have been made, industry have invested between $4 and 6 billion by 2013 to make further improvements in air quality. This investment is in addition to the substantial investment made in the 1990s.

The 2012 ozone design values for all Houston area regulatory ozone monitors except for one were below the 1997 8-hour ozone standard of 0.08ppm.

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Air Monitoring Comparison Values (AMCV)

TCEQ implemented use of the term “air monitoring comparison values” (AMCVs) to evaluate air monitoring data. AMCVs are chemical-specific air concentrations set to protect human health and welfare. Exposure to an air concentration at or below the AMCV is not likely to cause adverse health effects. AMCVs are a collective term that refers to all values used by TCEQ to review ambient air monitoring data. The short-term AMCV, based on acute exposure health and welfare data, is compared to monitored concentrations ranging from instantaneous to up to one hour. The long-term AMCV, based on chronic health and welfare data, is used to evaluate annual averaged monitored concentrations or annual concentrations averaged over multiple years (if available).

 In 2012, all monitored ambient VOC concentrations that were measured in the Houston Regional Monitoring (HRM) network were less than their respective TCEQ AMCVs in the Houston Ship Channel area. While historical concentrations of benzene above the annual benzene AMCV have been monitored at the Lynchburg Ferry site in recent years, TCEQ actions (working in cooperation with facilities that emit benzene) have resulted in significant reductions in the annual average benzene concentrations at this monitoring site. Since 2006, benzene levels at the Lynchburg Ferry have declined by over 70%. In 2012, all Houston area monitoring sites measured annual averages that were less than the long-term benzene AMCV. Another pollutant of interest in the Houston area is 1,3-butadiene. Like benzene, there has been a steady decline in the annual ambient concentration of 1,3-butadiene in the Houston area. The annual ambient concentration of 1,3-butadiene is below the TCEQ annual AMCV at all Houston area monitors. To date the greatest reduction in ambient 1,3-butadiene levels has occurred at the Milby Park monitor. These improved trends are the result of voluntary efforts to reduce the emissions from nearby industrial sources closest to the Milby Park monitor.

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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 to develop and implement  the Environmental Monitoring and Response System (EMRS) at the Lynchburg Ferry monitor. The program in concert with the Monument Area Air Quality Focus Group (MAAQFG) has resulted in a 70% reduction of ambient benzene levels at the Lynchburg Ferry since 2006. This has prompted the TCEQ to remove the Lynchburg Ferry monitoring site from the benzene air pollutant watch list in 2009.

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Last Update : 9/23/2013

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