Volatile Organic Compounds In Gas Stations

Volatile organic compounds, also known as VOCs are " Compounds that have a high vapor pressure and low water solubility " (EPA). This means that the VOCs evaporate easily and do not dissolve well in water. VOCs are present at gas stations as they are a component of fuel. They are released from refueling as well as fuel spills. VOCs are harmful as they worsen air quality, and cause many health problems like cancer. They are the cause of the hazardous air quality near gas stations. According to a study done by the Columbia University Mailman School of Public Health called, "  Gas Stations Vent Far More Toxic Fumes Than Previously Thought  ", it was found that VOC emissions at gas stations were ten times higher than they are supposed to be. Researchers measured evaporative losses of 1.7 and 1.4 pounds of liquid gasoline per 1,000 gallons at two large gas stations when the California Air Pollution Control Officers Association (CAPCOA) estimated that only 0.11 pounds per 1,000 gallons were being evaporated. This proves that gas stations have more of a negative impact on communities than most commonly realize. After visiting various gas stations in Glendale, California, and utilizing an Atmotube Pro to measure air quality, it was discovered that VOCs and particulate matter are being emitted into the air as cars refuel with gas.

The Atmotube Pro is a sensor that provides real-time measurements of particulate matter that ranges from PM1.0, PM2.5, and PM10 mass concentrations, as well as volatile organic compounds. The AtmoTube Pro also measures temperature, relative humidity, and pressure when used. With the use of this device, I was able to gather data at various gas stations.

Temperatures have a significant influence on the release of VOCs when refueling a vehicle. Gasoline is composed of over one hundred hydrocarbons, including VOCs such as benzene. As temperatures rise, the vapor pressure of these fuels also increases. This means that more fuel molecules escape and enter the air as vapors. On hot, humid days the elevated temperatures lead to higher levels of VOC emission during the refueling process. When refueling the car there are moments when gas might leak from the nozzle, especially when inserting or removing the nozzle from the gas tank. When these droplets of fuel land on the ground, the heat causes them to evaporate. The evaporation of these droplets also contributes to an increase in the level of VOCs present. Additionally when people top off their gas tanks, that also leads to gas spillage onto the ground. Apart from the fueling process itself, higher temperatures cause more VOCs to be released from the cars, as the temperatures that the vehicles operate at are higher than normal. On the other hand, cooler temperatures lower the amount of VOCs that are present. On cold, wet, and windy days the amount of VOCs present at gas stations will be low. These lower temperatures and rain will reduce the amount of fuel molecules that evaporate. The wind will also help spread out the VOCs that are released, lowering the concentration that is in the air.

With the use of the AtmoTube Pro, the measurements of the VOCs that are released from gas stations at different distances were collected.

The first photo was at the gas station 1ft away from the pump and we can see that it has the highest amount of VOCs present. The second photo was 50 feet away. This shows how only a little bit of distance can lower the amounts of VOCs significantly. The third photo is 100 feet away, and the VOC levels were significantly low, but it was not 0.00. Finally, the fourth photo shows 200 feet away from the gas station, where the VOC levels were finally 0.00.

After collecting data from distances away from the gas pump, the place that showed the most amount VOCs present was right next to the open gas tank. The worst place to stand when refilling a car is directly next to the gas pump. Those short moments when inserting and removing the nozzle from the gas tank itself are the moments that the exposure and concentration of the VOCs are the highest. Although those moments are short, the gas station is a place that is visited very often. This means that the amount of times one is exposed to these dangerously high amounts of VOCs is large.

One simple and cost-effective solution to this problem could involve implementing airtight seals (emission recovery nozzles) on gas pump hoses. These seals would effectively enclose the gas cap area of cars, preventing harmful VOCs from escaping into the air during refueling. While many gas stations, especially in California, already enforce this measure, making it a nationwide requirement for all gas stations could significantly reduce the emission of VOCs into the surrounding environment, ultimately positively impacting the entire United States.