Gas Station Prevalence
Gas stations have been an essential component that have helped to facilitate the widespread adoption of travel by personal vehicles. For decades, gas stations have been one of the most common elements of the American built environment. In fact, gas stations are so common across the U.S. that nearly 93 percent of all Americans live within only a few minutes of one (Ferris, 2020). As these businesses have evolved over the years, regional store chains like Sheetz, RaceTrac, and Wawa have started to compete against restaurants and coffee shops by offering a wide variety of food and beverages in addition to just simply being a place to fuel up a personal vehicle. The gas station and convenience store model has become so popular that one out of every three stores in the U.S. is labeled as a gas station or a convenience store (Ferris, 2020). While these businesses have clearly become a staple feature of mass motorization and American automobility, an abundance of scientific research regarding environmental and health concerns shows that it may be hazardous to live near a store that sells diesel fuel or gasoline.
Disconcerting Findings from Columbia University
A recent study conducted by a team of environmental health scientists from Columbia University’s Mailman School of Public Health found that many of the nation’s gas stations are leaking potentially hazardous vapors into the surrounding environment. Gas stations can have a significantly adverse impact on neighboring housing complexes, especially neighborhoods with young children. Despite the convoluted array of modern safety and health guidelines that gas stations must follow, these fossil fuel-selling businesses can emit high levels of ground-level ozone from gasoline fumes, impact groundwater systems from leaking fuel tanks, and expose nearby residents to a number of other hazards from other chemicals that might be used at a fuel station (Scientific American, 2009).
Study results from Columbia University’s Mailman School of Public Health revealed that vapors from gas station vent pipes often emit ten times the amount of emissions that were originally used to determine setback regulations for playgrounds, public parks, and schools. The findings were published in the journal Science of the Total Environment. The researchers highlighted that toxic gasoline and diesel chemicals may have been unknowingly exposing nearby residents to harmful carcinogens for decades. By attaching gas flow meters on venting pipes held at multiple gas stations in the Midwest and the Northwest, the researchers found elevated levels of vapors containing a number of toxic chemicals like benzene, which is a known a carcinogen. Over the past few decades, the average benzene content of gasoline has been approximately one to three percent in the United States and three to five percent in European countries (Infante, 2017).
Toxic Fuel Vapors
Over a period of three weeks, the gas flow meters reported average daily evaporative losses of between three and seven gallons of liquid gasoline, which is equivalent to about 1.4 pounds and 1.7 pounds per 1,000 gallons of gasoline distributed from the pump (Hilpert et al, 2019). These numbers may not mean much to the average citizen, but they are truly shocking when compared to the figures that were used to determine the safe setback distances for other land uses. For example, the California Air Pollution Control Officers Association (CAPCOA) utilized an estimate of 0.11 pounds of toxic vapor emitted per 1,000 gallons of gasoline (Columbia University, 2018). Through these CAPCOA gasoline emission estimates, members of the California Air Resources Board (CARB) established setback regulations of 300 feet from large gas stations. Since these estimates were found to be ten times lower than actual observed emissions, one would think that the setback requirements should be modified to be ten times the existing requirement.
Regulations similar to California’s gas station setback requirements can be found in most states and local municipalities. Although, some communities, especially in dense urban areas, do not require any specific setback regulations, which may expose countless numbers of residents to potentially toxic vapors. While gasoline vapors are known to contain harmful chemicals like benzene and volatile organic compounds, little is known about how long-term exposure to these chemicals may impact human health. Carbon monoxide, particulate matter, nitrogen oxides, and unburned hydrocarbons are emitted when gasoline evaporates or is burned. These contribute to air pollution and greenhouse gas emissions.
Exposure to Chemicals
According to the U.S. Energy Information Administration, the U.S. consumed about 392 million gallons of gasoline per day in 2018 (EIA, 2019). As gasoline consumption continues to rise, increasing levels of unburned fuel are released into the environment in the form of both liquid and vapor compounds. Workers dispensing fossil fuels and truck drivers that deliver gasoline and diesel have among the highest exposure to chemicals like benzene, ethyl-benzene, toluene, and xylenes (WHO, 2012). The World Health Organization has issued occupational warnings for workers that deliver fossil fuels to gas stations. Continuous exposure to these chemicals has been found to cause a number of cancers.
The Columbia University study raises serious questions about the safety of living within close proximity of gas stations. The California Office of Environmental Health Hazard Assessment has established a system known as one-hour Reference Exposure Level (REL) to evaluate the potential for benzene exposure. This system measures continuous exposure to the chemical over a period of one hour. The Columbia University researchers found the REL exposure was exceeded at both gas stations at distances greater than 50 meters away from the stations themselves. Moreover, the Agency for Toxic Substances and Disease Registry’s Minimal Risk Level (MRL) corresponding to a year’s worth of benzene exposure was exceeded within seven meters of the gas stations that were studied (Columbia University, 2018). However, it’s important to also note that the American Industrial Hygiene Association’s Emergency Response Planning Guidelines (ERPG) were not exceeded with regards to benzene exposure. Although, the ERPG uses a less stringent system to measure potentially harmful levels of benzene exposure.
Post-Research Interview with Markus Hilpert
In a post-research interview with Markus Hilpert, Ph.D., an associate professor of Environmental Health Sciences at the Columbia Mailman School, Hilpert said, “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” (Columbia University, 2018). He also highlighted that, “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” (Columbia University, 2018).
The U.S. Clean Air Act
The establishment of laws like the U.S. Clean Air Act have been aimed at reducing the impact that fossil fuels have on the environment and human health. Since it was first established in 1970, the Clean Air Act has primarily served as an environmental law that has reduced air pollution from vehicle tailpipe emissions. In order to meet air pollution goals, the U.S. Environmental Protection Agency has used the Clean Air Act to require emission control devices and cleaner burning engines, remove leaded gasoline for use in vehicles, require the use of reformulated gasoline, require the use of ultra-low sulfur gasoline, and reduce the risk of gasoline leaks from service stations. Amendments added to the Clean Air Act have had a profound impact on the environment and human health. However, the amendments have largely failed to address the release of vapors directly from gas stations.
Modern Fuel Vapor Controls
Most modern gas pumps are required to have government-regulated vapor-recovery units on their nozzles in order to limit the release of toxic gasoline and diesel vapors while a car is being refueled. When a tanker truck arrives to refuel the underground storage tanks at the gas station, a similar system of government-regulated vapor-recovery units are required to be used. However, these units often fail, while vent pipe emissions from the underground storage tanks frequently lack adequate air filters, as outlined by the study conducted by Columbia University. In addition to elevated levels of benzene, direct concerns related to gasoline fumes include the presence of ground-level ozone. Ozone pollution is known to be caused by a toxic mixture of volatile organic compounds which can be found in gasoline vapors. High levels of ozone are known to cause asthma and other respiratory problems. Furthermore, the National Institutes of Health says that volatile organic compounds can lead to certain types of cancers.
In addition to the concerns related to harmful vapors, leaks from gasoline storage tanks should also be a concern for homeowners that live near gas stations. According to data tracked by the U.S. Environmental Protection Agency, there are more than 660,000 underground gasoline storage tanks in the country. The vast majority of gas stations have underground fuel tanks that are made from uncoated steel, which are known to deteriorate over time. Once uncoated steel tanks start to rust, they are prone to fuel leaks. Many lawsuits have been filed over the years against gas stations with uncoated steel tanks for fossil fuel contamination that has leached into groundwater systems.
As gasoline enters the soil and begins to contaminate groundwater, it can be extremely challenging to address. According to the U.S. Environmental Protection Agency, groundwater systems supply nearly a half of all American households with water. If a storage tank were to leak and contaminate a groundwater system with gasoline additives like methyl tertiary-butyl ether, the groundwater could potentially be rendered permanently undrinkable. While this chemical has been outlawed in a number of states, methyl tertiary-butyl ether is only one of nearly 150 harmful chemicals that can be found in gasoline (Scientific American, 2009). While the notion of permanently contaminated drinking water can be a difficult concept to grasp, lawmakers have been working to reduce the risk of fuel tank leaks. For example, a federal law enacted in the 1990s started to mandate a phased removal of older underground fuel storage tanks to be replaced with new doubled-lined tanks.
The National Library of Medicine at the National Institutes of Health has published countless of research reports on the dangers of repeated exposure to liquid and vaporized gasoline. Lung, brain, and kidney damage are frequently cited as the most pressing health areas of concern. In today’s auto-oriented world, it can be challenging to avoid exposure to these toxins founds in gasoline and diesel fuel. Once these chemicals are released into the atmosphere from vehicle tailpipes and other non-point sources, it can be nearly impossible to completely avoid these chemicals. However, with due diligence, a homeowner can reduce long-term risk by avoiding homes that are located in close proximity to gas stations.
Columbia University. (2018). “Gas stations vent far more toxic fumes than previously thought.” Columbia University’s Mailman School of Public Health.
EIA. (2019). “Gasoline Explained.” U.S. Energy Information Administration.
Ferris, F. (2020). “America’s gas stations and convenience stores grapple with an uncertain future.” CNBC.
Hilpert, M., et al. (2019). “Vent pipe emissions from storage tanks at gas stations: Implications for setback distances.” Science of The Total Environment: Volume 650, Part 2, Pages 2239-2250.
Hilpert, M., et al. (2015). “Hydrocarbon Release During Fuel Storage and Transfer at Gas Stations: Environmental and Health Effects.” Current Environmental Health Reports: Volume 2, Issue 1, Pages 412–422.
Infante, P. (2017). “Residential Proximity to Gasoline Stations and Risk of Childhood Leukemia.” American Journal of Epidemiology: Volume 185, Issue 1, Pages 1-4.
NIH. (2020). “Why are Gas Stations a Concern?” National Institutes of Health: Department of Health & Human Services.
Scientific American. (2009). “Is It Safe to Live Near a Gas Station?” Scientific American: Division of Springer Nature America, Inc.
WHO. (2012). “Chemical Agents and Related Occupations.” World Health Organization: International Agency for Research on Cancer.