COLLEGE STATION, Texas, April 15, 2004 (ENS) – "Houston's air pollution levels are nearly double the national standard during summer days, smog concentrations that could pose a serious health risk to the city's inhabitants unless controlled, a Texas A&M University researcher has found.
Renyi Zhang, associate professor of atmospheric sciences, modeled Houston's air during the summer months. He found that at night, the city's ozone level was near zero, but during the day it zoomed to more than 200 parts per billion (ppb), far higher than the U.S. standard of 120 ppb.
The reason for the high daytime rating, Zhang says, can be traced to the huge refineries and petrochemical complexes in the area, plus the large amount of auto exhaust in Harris County. The highest ozone levels were found around the city's southeastern edge near the huge petrochemical plants. "These plants emit large amounts of highly reactive volatile organic compounds and nitric oxides," Zhang says. "At midday, the ozone readings are very high because of the industrial emissions, coupled with auto exhaust. It creates very big problems for Houston's air, and ozone levels are far above acceptable federal standards."
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The fourth largest U.S. city, Houston has one of the worst ozone levels in the country, due to the fact that 50 percent of the nation's petroleum refining capability is within the city limits. "There are around five million people in the greater Houston area, and many of these people could have health problems associated with breathing bad air, such as emphysema and asthma," Zhang explains."
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http://forests.org/articles/reader.asp?linkid=30836