The Houston metropolitan area is one of the nation's hot spots for toxic air pollution, but few community leaders and even fewer area residents are aware of the problem's extent. No other document on air pollution in this region begins to address air toxics with such completeness. Contrary to popular belief, the criteria pollutants are the only pollutants regulated in ambient air by the federal government. Air toxics are defined primarily by their effects. Exposure to air toxics increases an individual's risk of developing cancer, immune and neurological damage, and reproductive and endocrine problems, as well as increasing the risk of birth defects in children.
Most health problems associated with air toxics take years to develop.
Many VOCs, but by no means all, are also air toxics. The state of Texas has established guidelines for acceptable maximum levels of toxic pollution in ambient air, but these are not enforceable standards. Designated industries releasing significant amounts of any of these toxic substances into the environment are required to provide the federal government with annual estimates of how much of each chemical they release. The six criteria pollutants, the VOCs, and the air toxics are often discussed as though they were quantifiably distinct entities. This is not the case.