by John Melvin
September 12, 2024

While research on the public health risks for residential proximity to gas stations is still in its infancy, enough studies have found significant relationships between proximity and adverse health outcomes to justify application of the precautionary principle with regard to siting gas stations near residences, medical facilities, schools, daycare centers and parks. 

The negative health outcomes studied include adverse pregnancy outcomes, birth defects, infant deaths, childhood cancers (including leukemia, brain cancer, germ-cell tumors, non-Hodgkin’s lymphoma, and Burkitt lymphoma), asthma and other chronic respiratory symptoms, stroke, renal disease, and diabetes. The evidence at this time is sufficient to justify the application of the precautionary principle to protect people from the deleterious effects of living near environmental hazards. (1)

One hazard of particular interest for nearby neighborhoods of any proposed gas station is the chemical, benzene, a gasoline additive. Benzene is a colorless or light yellow liquid at room temperature with a sweet odor. It is highly flammable.

Benzene evaporates very quickly; however, its vapor is heavier than air and may sink into low-lying areas. This is a concern for gas stations built on ridges above lower elevation areas—which was the case for the Parker’s Kitchen at Stratford Drive and Whiskey Roads proposal, and remains the case for the current proposed Chukker Creek and Whiskey Roads station.

Emissions from gas stations and motor vehicle exhaust are two primary sources for human exposure to benzene. Air around gas stations can contain higher levels of benzene than in other areas of the city. This burden is compounded by the background level resulting from vehicle exhaust, which can be elevated in areas with dense traffic conditions.

Benzene is part of an additive called BTEX — Benzene, Toluene, Ethyl Benzene and Xylenes. BTEX is used for increasing gasoline octane levels to support for proper operation of engine combustion process. It replaced lead as an additive for this function. 

All gas stations have storage tanks either above ground or under ground (UGSTs). All fuel storage tanks must have vents to protect the storage tanks from excessive positive pressure or collapse damage caused by excessive vacuum. Venting is accomplished by using 12 to 15 foot high vent pipes on the tanks, which allows escaping vapors such as BTEX to be emitted high enough to allow the vapors to be diluted in the air near the gas station. 

Gas stations with large volume fuel sales (more than 100,000 gallons per month) are required to utilize pressure vacuum valves on storage tank vents to reduce the vapor emissions, while providing protection of the physical integrity of the storage tanks. The set points of these pressure and vacuum relief valves is extremely low and measured in inches of water. The California Air Resource Board (CARB) has established the procedures and maintenance requirements for these valves, which are now required by all 50 states to enforce for all large volume gas stations.

The CARB has also established the estimated gasoline vapor releases from a gas station to be approximately .11 pounds of gasoline lost to vapor loss per 1000 gallons pumped. Using this estimate, a safe distance of 300 feet separation between residential housing and “sensitive land uses” such as schools, daycare centers, playgrounds, or medical facilities was recommended by CARB. 

The EPA adopted this recommendation and included it in their School Siting Guidelines. Numerous municipalities around the country have adapted this recommendation in their zoning ordinances. Current research available at the National Institute of Health’s (NIH) National Library of Medicine (NIM) , specifically the in-field real world sampling of large gas station emission by Colombia University in conjunction with John Hopkins and Arid Technologies. 

Their research showed that the CARB estimate of 0.11 pounds of gasoline lost to vapor loss was under estimated and found to be approximately 1.7 pounds per 1000 gallons pumped. This translates into an approximate loss of 7 gallons of gasoline lost to evaporation daily. This is a 10 times higher number than estimated and results in a recommended change of the recommended 300 feet to a more appropriate safety distance of 1000 feet. 

This is significant considering that gasoline has been reconfigured numerous times to achieve a previous level of 3 to 5 percent Benzene content to the most recent (2001) of 0.65 percent to 1.25 percent (e.g., 87 Octane to 92 Octane). This updated recommendation has been adopted by the EPA and updated in their School Siting Guidelines. 

Searches for nearby municipalities found numerous examples that this has is being incorporated in municipal zoning ordinances. A great example was found in Thomaston, Georgia, where 1000 feet of safety separation is mandated. Thomaston also has a requirement to separate gas stations by one-half of a mile.

Review of Aiken City Ordinances found no separation requirements for siting gas stations near a school, residential area or places where people assemble (e.g., parks, libraries, etc.). The zoning ordinances lack specificity and detail and requiring Aiken City council to exercise discipline in using their discretionary authority to achieve safety, health and well being for our children and the general public when approving the siting of gas stations/fuel sales. 

Zoning ordinance 4.3.8 specifically states that there is no entitlement of use or intensity of use, therefore even if allowed by zoning standard use table, city council can disapprove a concept plan if it challenges the primary and paramount duty and responsibility to ensure safety, health and general well being above any consideration to facilitate economic growth and business development.  This is clearly the guidance of Aiken City Zoning Ordinance 1.1.3 “Purpose”. 

Aiken City officials need to remain abreast of credible and documented research and information, which is based on sound scientific and engineering judgments to assist in their decisions when it impacts their citizens and the community as a whole.

This write up relies on reference materials from the CDC, EPA, OSAH, NIOSH, CARB, Thomaston Georgia City Zoning Ordinances and documents retrieved from the NIH/NLM web sites. It is presented with no intended malice or intent to misinform.

(1) “Residential Proximity to Environmental Hazards and Adverse Health Outcomes.” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3222489/