Health hazards: benzene and fuel exposure

Fire is the hazard everyone thinks of at a fuel station, but fuel also affects health more quietly. The smell of gasoline at the pump is vapor entering your nose and lungs. Fuel splashed on hands soaks into the skin. A mouthful of gasoline while siphoning, a common mistake, can be deadly. For most self-serve cashiers the exposure is small and brief. For full-serve attendants who fuel vehicles all day, for workers who clean up spills, and for anyone who handles fuel often, it is worth understanding what the hazards are and how to keep exposure low.

This lesson covers how fuel enters the body, the specific concern of benzene, exposure limits and how they apply at a station, skin contact, swallowing and aspiration, carbon monoxide, and practical ways to reduce exposure. HSE-103 covers hazard recognition generally and HSE-106 covers first aid response in more depth.

How fuel gets into the body

• Breathing vapor: the main route. Vapor rises from the fill neck of a vehicle during fueling, from spills and from open containers. The concentration is highest right at the opening and falls quickly with distance and with wind.
• Skin contact: gasoline and diesel remove the skin's natural oils, causing dryness, cracking and dermatitis with repeated contact, and some components are absorbed through the skin. Fuel trapped against the skin in a soaked glove or sleeve can cause chemical burns.
• Swallowing: usually from siphoning or from drinking from a mislabeled bottle. The big danger is aspiration: fuel is thin and slippery, and if it gets into the lungs, even a small amount, it causes a severe chemical pneumonia.
• Eyes: splashes sting and can injure the eye surface.

Benzene

Gasoline contains a small amount of benzene, a hydrocarbon that is a known human carcinogen. Long-term exposure to benzene at high levels causes leukemia and other blood disorders; this is well established from studies of workers in industries where exposure was much higher than at a modern fuel station. Benzene is the reason gasoline's safety data sheet lists cancer hazards, and the reason governments limit how much benzene gasoline may contain.

In the United States, EPA rules limit benzene in gasoline to an annual average of 0.62% by volume, with a cap on any batch. Typical retail gasoline contains well under 1% benzene, so the benzene in the vapor at the pump is a small fraction of a small fraction.

Studies of fuel station attendants who fuel vehicles all day have measured benzene exposures that are usually far below the limits that applied when the studies were done, but not zero, and higher for attendants in hot weather, at busy stations, and where vapor recovery is not used. Self-serve cashiers inside the store have much lower exposure still. The aim is to keep exposure as low as reasonably achievable, because there is no clearly safe level for a carcinogen.

Exposure limits

Occupational exposure limits set the maximum average concentration of a substance a worker may breathe, usually over an eight-hour shift (a time-weighted average, TWA), and sometimes over a short period such as 15 minutes (a short-term exposure limit, STEL).

OSHA's benzene standard (1910.1028) sets a permissible exposure limit of 1 ppm as an eight-hour average, 5 ppm over 15 minutes, and an action level of 0.5 ppm that triggers monitoring and medical surveillance. However, that standard does not apply to the dispensing and sale of gasoline after it leaves bulk storage, except where fuel is dispensed indoors for more than four hours a day, so a typical outdoor station is outside it. The American Conference of Governmental Industrial Hygienists (ACGIH) lowered its recommended benzene limit to 0.02 ppm as an eight-hour average in December 2023, fifty times lower than OSHA's limit. Under the General Duty Clause, employers are still expected to control serious recognized hazards, and good practice is to keep exposure as low as reasonably achievable.

Working out a time-weighted average

An eight-hour time-weighted average is worked out by multiplying each measured concentration by the time spent at it, adding them up and dividing by eight hours. Short, high exposures, such as cleaning up a spill, add to the average even if most of the shift is spent inside. The program below uses invented air sampling results for a full-serve attendant at a busy station on a hot day, a situation Northfield does not have but which some stations do, and compares the result with the limits.

# Eight-hour time-weighted average benzene exposure (invented sampling results).
periods = [  # (activity, hours, benzene ppm during that time)
    ("fuelling vehicles, morning", 3.0, 0.030),
    ("inside store", 1.5, 0.002),
    ("fuelling vehicles, afternoon heat", 2.5, 0.050),
    ("cleaning up a small spill", 0.25, 0.400),
    ("break, upwind", 0.75, 0.001),
]
total = sum(h for _, h, _ in periods)
twa = sum(h * c for _, h, c in periods) / 8
print(f"Hours sampled: {total}")
print(f"8-hour TWA: {twa:.3f} ppm")
for name, limit in (("ACGIH TLV (2023)", 0.02), ("OSHA action level", 0.5), ("OSHA PEL", 1.0)):
    print(f"{name:20} {limit:>5} ppm -> {twa / limit:5.1%} of limit")
spill = 0.25 * 0.400 / 8
print(f"Share of TWA from the 15-minute spill clean-up: {spill / twa:.0%}")

Hours sampled: 8.0
8-hour TWA: 0.040 ppm
ACGIH TLV (2023)      0.02 ppm -> 199.2% of limit
OSHA action level      0.5 ppm ->  8.0% of limit
OSHA PEL               1.0 ppm ->  4.0% of limit
Share of TWA from the 15-minute spill clean-up: 31%

The attendant's eight-hour average of about 0.04 ppm is less than a tenth of the older limits, but about twice the ACGIH value adopted in 2023. Fifteen minutes of spill clean-up contributes almost a third of the day's exposure, which shows why spill response deserves care: work from upwind, use absorbent rather than leaning over the pool, and do not linger. The numbers are invented for teaching, but the pattern, that short close-up tasks dominate, matches what real sampling usually finds.

Who is most exposed at Northfield

At Northfield, which is self-serve, nobody fuels vehicles all day, so routine benzene exposure is low. The tasks that bring staff closest to fuel are occasional: cleaning up spills at the pumps, helping a customer whose nozzle will not shut off, watching a delivery at the fill ports, changing a damaged nozzle or hose with the service contractor, and handling leaking containers that customers bring back. Leah's hazard assessment lists each of these, with the controls for each: nitrile gloves and safety glasses in the spill kit, standing upwind, using the absorbent sock and pads rather than rags, bagging soaked absorbent promptly, and washing hands before eating or smoking. The assessment also notes that pregnant workers or workers with health concerns can ask to be kept away from spill clean-up, which is easy to arrange on a shift with two people.

Carbon monoxide and exhaust

Vehicle exhaust contains carbon monoxide, a colorless, odorless gas that prevents the blood from carrying oxygen. On an open forecourt, it disperses quickly. It becomes a hazard in enclosed spaces: a car wash bay with the doors closed in winter, a service bay, a delivery bay or a kiosk where idling vehicles line up close to an air intake. Symptoms are headache, dizziness, nausea and confusion. If workers in an enclosed car wash or a small kiosk report these symptoms, get them into fresh air, ventilate, and have the space checked. Lesson 10 covers car washes.

Skin protection

Gasoline on the skin evaporates quickly, so brief splashes do little harm beyond drying, but repeated contact causes dermatitis, and fuel trapped against the skin can burn. Workers who handle fuel nozzles all day, clean up spills or service equipment should wear chemical-resistant gloves. Nitrile gloves resist gasoline and diesel for short contact and are the usual choice; thin latex or vinyl gloves do not protect well. Change gloves that become soaked, wash skin that gets fuel on it with soap and water rather than rubbing it with more fuel or solvent, and remove fuel-soaked clothing promptly, away from ignition sources, because soaked clothing is both a skin hazard and a fire hazard.

Swallowing and siphoning

Customers sometimes ask for help siphoning fuel from a tank, or try it themselves on the forecourt. Never siphon fuel by mouth, and never help a customer do so. Swallowed gasoline can enter the lungs as the person coughs or vomits, and causes a serious chemical pneumonia that can kill. If someone swallows fuel, do not make them vomit; call 911 or the poison center and follow their advice. Keep fuel only in approved, labeled containers (Lesson 6), never in drink bottles, which is how many accidental poisonings of children happen.

First aid for fuel exposure

For supervisors: reduce exposure without fuss

Most exposure reduction at a station is simple. Keep vapor recovery equipment in good repair, where it is required. Make sure staff fuel from upwind when they have to fuel a vehicle and do not lean over the fill neck. Provide nitrile gloves and make sure they are used for spills. Train staff to clean up spills with absorbent and long-handled tools, not by leaning over the pool. Keep the store door closed when a large spill is being cleaned up outside so vapor does not drift in. And keep an eye on staff who regularly complain of headaches or nausea; it may be exposure, or it may be something else, but it is worth checking.

Pregnancy, young workers and sensitive workers

Some workers may want or need extra care with fuel exposure: people who are pregnant or planning a pregnancy, young workers, and people with asthma or skin conditions. The exposures at a self-serve station are low, but it is reasonable to arrange work so that these workers are not the ones cleaning up spills or standing at the fill ports during deliveries, especially on hot days. Workers do not have to explain their reasons in detail; the manager should simply make the change where it can be made, as Northfield does.