| A new report recommends immediate action to reduce the levels of four toxic air pollutants in Houston. The study proposes new air quality standards based on the toxicology of the four pollutants: benzene, 1, 3-butadiene, formaldehyde and diesel particulate matter. For example, the report found that the 2004 annual average concentration of 1, 3-butadiene in Houston was four parts per billion (ppb) -- about 20 times greater than Los Angeles, the city with the second-highest measured levels. |
