Comparative Assessment of Air Pollution-Related Health Risks in Houston
Ken Sexton, Stephen H. Linder, Dritana Marko, Heidi Bethel and Philip J. LupoEnvironmental Health PerspectivesVol. 115, No. 10 (Oct., 2007), pp. 1388-1393
Houston's air pollution levels have long been at unacceptable levels according to the EPA. Therefore, Mayor Bill White organized a task force featuring members from Texas universities and EPA staff to analyze pollutants in the city and identify the highest priority groups among them. Out of 179 pollutants identifies, about 12 of them were rated as definitely posing a risk to human health. The distribution of these pollutants was unequal, as a high concentration of high-risk pollutants were found in neighborhoods along the Houston Ship Channel.
The report was presented by Heidi L. Bethel, who is an environmental scientist at the E.P.A. Ken Sexton is another author in this report, and he works as professor of epidemiology at the University of Texas School of Public Health. He has received multiple grants from the E.P.A to investigate pollutants and the effects of exposure to them.
The main findings of this article are that twelve air pollutants have been identified as definitely causing adverse health risks, and of those twelve, nine are present in Houston at levels that present an unacceptable increase in the risk of cancer. These include ozone, benzene, and Chromium VI. The study also found eight other compounds that are also carcinogenic, but have less evidence to warrant designating them as 'definitive' health risk. These include napthalene and carbon tetrafluoride.
The findings on the potency of the carcinogens are based on previous human and animal trials to see if exposure to these substances led to cancer or some other chronic ailment at some point in the future. The information from these studies then to classifications based on the amount of cancers formed after exposure. That the concentrations of these carcinogens is far beyond the acceptable range is supported by the E.P.A's toxicity values for each compound.
“Which ambient air pollutants are most likely to cause significant health risks for current and future residents of Houston?”
“Pollutants which were judged to present a definite risk include ozone, fine particulate matter (PM2.5), diesel particulate matter and nine hazardous air pollutants (HAPs): 1,3-butadiene, chromium VI, benzene, ethylene dibromide, acrylonitrile, formaldehyde, acrolein, chlorine and hexamethylene diisocyanate”
“The median level of family income in our 9 super-neighborhoods is more than 30 percent lower than for the City of Houston; over a quarter of the residents fall below the poverty level. Almost 20 percent of the residents have less than a ninth grade education. These neighborhoods have some of the highest uninsured rates for health coverage in Harris County.”
The E.P.A set up 20 collection sites around the Greater Houston area to gather data on pollutant concentration. The study also relied on computer models made by the E.P.A for the 1999 National Scale Air Toxics Assessment (NATA). The toxicity values were based on established reference values set by the E.P.A and the respective Unit Risk Estimate for every microgram per cubic meter of pollutant in the air.
Health disparities are addressed by noting some specifics about the population along the Houston Ship Channel, the most polluted region of Houston. Over a quarter of the population in Harrisburg/Manchester and Clinton Park, some of the neighborhoods along the Houston Ship Channel, lives below the poverty line or has less than a high school education. The population of Harrisburg/Manchester is 88% Hispanic, while Clinton Park is 90% African American
This article has been cited by at least five other studies, such as one about the toxicity of benzene. Most of the studies citing this report focused on Houston and Harris County in particular, though each had a different focus. One focused on Houston's air control policy, and another two talked about ozone and PM2.5 and how they relate to emergency room visits.
About half of the references in this report are from the U.S. E.P.A. Seeing this many sources from the E.P.A does reinforce that this paper is a government report. Two more citations are from the California E.P.A, and one paper features author credits from some of the contributors to this report. None of the citations are from papers specifically about Houston, which could mean that the authors of this paper did not find anything worth citing on this subject in Harris County.
Next, I took a look at the ASPEN model, since that was mentioned in the report multiple times. The ASPEN model is a way of measuring emissions from nonpoint sources that are spread out over a wide area of release. This model takes into account variables like reactive decay of pollutants, height of release of pollutants, and wind speeds when the pollutants were released, among other things.
Finally, I read an article titled “In Harm's Way”, by Dina Cappiello that was featured in the Houston Chronicle in 2005. In it, reporters recorded pollutant levels outside of refineries using industry standard equipment, and found unsafe levels of benzene and 1,3-butadiene. Supposedly, this article helped inspire Mayor Bill White's push to fight air pollution and organize this report to analyze the toxicity of the city (http://www.chron.com/news/article/Chronicle-cross-county-study-reveals-risky-load-1643020.php ).
Addendum:
This report does relate to our findings about ports becoming important sites for monitoring air pollution. This report found that the neighborhoods with the highest concentrations of pollutants were those lying on the shipping channel and closest to the shipping traffic.
Ken Sexton, Stephen H. Linder, Dritana Marko, Heidi Bethel and Philip J. LupoEnvironmental Health PerspectivesVol. 115, No. 10 (Oct., 2007), pp. 1388-1393
Houston's air pollution levels have long been at unacceptable levels according to the EPA. Therefore, Mayor Bill White organized a task force featuring members from Texas universities and EPA staff to analyze pollutants in the city and identify the highest priority groups among them. Out of 179 pollutants identifies, about 12 of them were rated as definitely posing a risk to human health. The distribution of these pollutants was unequal, as a high concentration of high-risk pollutants were found in neighborhoods along the Houston Ship Channel.
“Pollutants which were judged to present a definite risk include ozone, fine particulate matter (PM2.5), diesel particulate matter and nine hazardous air pollutants (HAPs): 1,3-butadiene, chromium VI, benzene, ethylene dibromide, acrylonitrile, formaldehyde, acrolein, chlorine and hexamethylene diisocyanate”
“The median level of family income in our 9 super-neighborhoods is more than 30 percent lower than for the City of Houston; over a quarter of the residents fall below the poverty level. Almost 20 percent of the residents have less than a ninth grade education. These neighborhoods have some of the highest uninsured rates for health coverage in Harris County.”
Next, I took a look at the ASPEN model, since that was mentioned in the report multiple times. The ASPEN model is a way of measuring emissions from nonpoint sources that are spread out over a wide area of release. This model takes into account variables like reactive decay of pollutants, height of release of pollutants, and wind speeds when the pollutants were released, among other things.
Finally, I read an article titled “In Harm's Way”, by Dina Cappiello that was featured in the Houston Chronicle in 2005. In it, reporters recorded pollutant levels outside of refineries using industry standard equipment, and found unsafe levels of benzene and 1,3-butadiene. Supposedly, this article helped inspire Mayor Bill White's push to fight air pollution and organize this report to analyze the toxicity of the city (http://www.chron.com/news/article/Chronicle-cross-county-study-reveals-risky-load-1643020.php ).
Addendum:
This report does relate to our findings about ports becoming important sites for monitoring air pollution. This report found that the neighborhoods with the highest concentrations of pollutants were those lying on the shipping channel and closest to the shipping traffic.