BLOOMINGTON, Indiana – People living or working near gas stations, as well as motorists who refuel their vehicles, might be exposed to a far higher level of toxic fumes than previously thought, according to new research by scientists at Columbia and Johns Hopkins universities.
In Indiana, authorities have no requirements for gas stations to install vapor recovery systems to trap these fumes, which come from vent pipes attached to gasoline storage tanks. And there are no state regulations requiring gas stations to be located at a certain distance from other structures.
“It turns out there are additional sources where unburned gasoline is released at gas stations, and I believe most people don’t know about it,” said lead researcher Markus Hilpert, associate professor of environmental health science at Columbia University. “These are releases from storage tanks. These tanks have a vent pipe which releases the fuel vapors to the atmosphere once the tanks get over pressurized, and it’s really a hidden source.”
Hilpert and his colleagues discovered that vent pipes at gas stations released 10 times the amount of benzene, a known carcinogen, than previously assumed in modeling used to determine how far gas stations should be placed away from sensitive sites like homes and schools. He says his research revealed that current regulations are insufficient to protect people from all toxic chemical exposure near gas stations.
A recent analysis published in the American Journal of Epidemiology found an elevated risk of childhood leukemia among children living near gas stations.
Gasoline is produced from petroleum and contains more than 150 chemicals, including benzene and the toxic chemicals toluene and xylene. Gas stations store gasoline in storage tanks either underground or on ground level.
Vent pipes keep pressure in the tanks steady by discharging chemical vapors that build up in the tanks. The pipes are 1 to 2 inches in diameter and are usually placed about 4 meters, or about 13 feet, above ground.
The research team attached gas flow meters to the venting pipes at two gas stations and took measurements for three weeks. They recorded 1.4 pounds of chemical vapors released per 1,000 gallons sold at a midwestern gas station, and 1.7 pounds of chemical vapors released per 1,000 gallons sold at a gas station in the northwestern part of the country.
Those levels were about 10 times the amounts estimated by the California Air Pollution Control Officers Association’s Industrywide Risk Assessment Guidelines, one of the only efforts to standardize chemical emissions measurements in the country.
Both federal law and Indiana law have some regulations governing gasoline dispensing facilities. But the laws in both cases are broad and do not impose specific measures or limits on individual gas stations, except when gas is in the process of being loaded from delivery tankers to storage containers.
For example, Indiana law says gas station owners and operators are “required to minimize evaporation by improving work practices,” such as minimizing gasoline spills, cleaning up spills quickly, and covering open gasoline containers and storage tank fill-pipes when they’re not in use.
Some facilities around the country have vapor recovery systems that suck up the vapors and pump them back into the storage tanks, drastically reducing the amount of chemical discharge. But Indiana has no requirements to install these systems.
In California, based on cancer risk estimations, the state requires gas stations to be located at least 300 feet from daycares, schools and other sensitive areas. But Indiana, like most states, allows setback distances between gas stations and other properties to be set by local governments, which results in a wide variation of rules.
“[T]he Indiana Building Code does not have guidelines on zoning-related setback distances for properties,” said Ashley Steeb, public information specialist for Indiana’s Department of Homeland Security, in an e-mail. “The Indiana Building Code, which is enforced by the local building officials as well as the Indiana Department of Homeland Security, focuses on regulations related to building and fire safety. Zoning-related setback distances for properties are regulated on the local level.”
Indianapolis, South Bend and Bloomington regulate gas station placement by requiring permitting and limiting where in a city they can be placed. Indianapolis’ zoning ordinance is the only one of the three that specifically requires that gas station setback distance. Gas stations in Indianapolis must be at least 100 feet away from transit stations, but there is not specific setback distance for any other structures like homes or schools.
The limited regulations impact local residents by potentially placing the source of contamination just feet away from homes and restaurants.
“As this contaminant moves downwind, it spreads out and eventually it can reach the ground level,” Hilpert said. “Or, potentially, if you have nearby residents that live at a four-meter elevation, they can be exposed to these vapors.”
Hilpert says most people do not know about the vent pipe emissions because the pipes are obscured and releases happen mostly at night.
“They’re really hidden,” Hilpert said. “At gas stations, these vent pipes are integrated into the canopy, so you cannot even see them.”
The researchers also found that despite more refueling activity during the day, emissions from the gas stations were higher at night, potentially exposing people to benzene in their sleep.
Hilpert says he hopes regulators use his findings to determine safer setback distances. He says at the very least the findings merit further investigation.