Vapors released from gas station vent pipes are 10 times more toxic than previously thought, according to a study by environmental health researchers at Columbia University Mailman School of Public Health, bringing into question the safety of schools, playgrounds and parks in close proximity to gas stations. Gasoline vapors contain numerous toxic chemicals, including the carcinogen benzene. Benzene exposure has been linked to blood cancers like acute myeloid leukemia (AML).
For the study, gas flow meters were attached to venting pipes at two large gas stations – one each in the Midwest and Northwest – to gauge measurements over a three-week period. Researchers noted a daily average evaporation loss of 7 and 3 gallons of liquid gasoline, respectively – or 1.4 pounds and 1.7 pounds per 1,000 gallons dispensed at the pump.
The California Air Pollution Control Officers Association (CAPCOA) follows an estimate of 0.11 pounds per 1,000 gallons, set by the California Air Resources Board (CARB), to determine its setback regulation for schools, playgrounds and parks of 300 feet (or 91 meters) from large gas stations. Not all states follow this strict setback rule. For example, New York City allows gas stations to be set up adjacent to apartment buildings. Researchers used this measurement for comparison.
Researchers also investigated how far fuel vapor could carry in the air to determine short- and medium-term benzene exposures at the two gas stations. They found that both exceeded the one-hour reference exposure level, as defined by the California Office of Environmental Health Hazard Assessment, that extended as far as 160 meters. Also, the Agency for Toxic Substances and Disease Registry’s Minimal Risk Level (MRL) for benzene exposure from two weeks to a year was exceeded within 7 to 8 meters of the two gas stations.
“We found evidence that much more benzene is released by gas stations than previously thought. In addition, even during a relatively short study period, we saw a number of instances in which people could be exposed to the chemical at locations beyond the setback distance of 300 feet,” said the study’s author Markus Hilpert, PhD, associate professor of Environmental Health Sciences at the Columbia Mailman School. “Officials should reconsider their regulations based on these data with particular attention to the possibility of short spikes in emissions resulting from regular operations or improper procedures related to fuel deliveries and the use of pollution prevention technology.”
Source: Science Daily