Gas stations release much more toxic fumes than we thought

A study conducted by environmental health scientists at the Columbia University Mailman School of Public Health examined the release of vapors from gas station ventilation pipes. Emissions were 10 times higher than those used in the setback regulation used to determine location at the facilities. The results appear in the log Total environmental science.

Gasoline vapors contain a number of toxic chemicals, including benzene, a carcinogen.

The researchers connected gas flow meters to the ventilation pipes of two large Midwest and Northwest gas stations and took measurements over a three-week period. They report average evaporative daily losses of 7 and 3 gallons of liquid gasoline, respectively, 1.4 pounds and 1.7 pounds per 1000 gallons dispensed at the pump. In comparison, CAPCOA (California Association of Air Pollution Officers) used an estimate of 0.11 pounds per 1,000 gallons. On the basis of CAPCOA's emissions estimates, the California Air Resources Board (CARB) has determined the regulation of its 91-meter (300-foot) withdrawal from major service stations. Similar laws exist in many states and localities, but not in all. In urban areas such as New York City, some service stations are directly adjacent to apartment buildings.

The study also simulated how fuel vapors were transported in the air in order to assess the potential for benzene exposure in the short and medium term, comparing their measurements to three thresholds established. The one-hour reference exposure level (REL) for benzene – defined as one hour of continuous exposure to the chemical – was exceeded in both gas stations at distances greater than 50 meters. At the Midwest Service Station, the REL was exceeded on two different days at distances greater than 50 meters and once at 160 meters. The minimum risk level (MRL) of benzene exposure over a two week to one year period of the Toxic Substances and Disease Agency was exceeded at 7 or 8 meters from both stations -service. A less stringent measure used for short-term exposures of first responders, the Emergency Planning Guidelines (ERPG) of the American Industrial Hygiene Association, was not exceeded.

"We found evidence that gas stations were releasing much more benzene than previously thought, and even during a relatively short period of time we saw from a number of cases in which people could be exposed to this chemical 300 feet, "said the first author Markus Hilpert, Ph.D., associate professor of Environmental Health Sciences at the Columbia Mailman School . "Managers need to reconsider their regulations based on this data, paying particular attention to the possibility of large increases in emissions resulting from routine operations or inappropriate procedures related to fuel deliveries and the 39, use of pollution prevention technologies. "

In previous work, Hilpert and his colleagues documented the release of gasoline in the form of fuel stored and transferred between tank trucks, storage tanks and vehicle tanks, as well as the manner in which these spills can contaminate the vehicle. surrounding environment. Researchers will then explore other short-term measures of steam propagation to determine the limits of safety margins.

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More information:
Markus Hilpert et al, Ventilation pipe emissions from service station storage tanks: consequences for setback distances, Total environmental science (2018). DOI: 10.1016 / j.scitotenv.2018.09.303