H₂S Mythbusters: Separating Facts from Fatal Mistakes

At Cochrane Emergency Training Services, we believe knowledge is your first line of defense. Understanding the facts about hydrogen sulfide can prevent tragedy and keep your crew safe. Book your next H₂S Alive or refresher course in Cochrane today — and make sure everyone goes home safely.

Myth #1: You can get used to the smell of H₂S, so it’s not that dangerous.

False — hydrogen sulfide can paralyze your sense of smell within minutes. You might notice

a 'rotten egg' odour at first, but then smell nothing even as the gas concentration increases.

That’s why relying on your nose instead of a detector is one of the most dangerous mistakes

you can make.

Myth #2: If you feel dizzy around H₂S, just move upwind and you’ll be fine.

Wrong — by the time you feel dizzy, you’ve likely inhaled a dangerous dose. H₂S acts

quickly on your nervous system, and unconsciousness can occur in seconds at higher levels.

Always use proper respiratory protection and evacuation procedures, not instincts.

Myth #3: H₂S only occurs in oil and gas sites.

Nope — it can show up in any environment where organic matter decomposes. That

includes sewers, manure pits, pulp mills, and even some water treatment facilities. Anyone

working around confined spaces or decaying material should be aware of the risk.

Myth #4: You can tell if H₂S is present because it burns your eyes or throat.

Not true — those symptoms only happen at certain concentrations and vary by person. At

lethal levels, H₂S can knock you down before irritation even starts. The only reliable

warning comes from a calibrated gas monitor.

Myth #5: Once a worker passes out from H₂S, it’s safe to rush in and rescue

them.

Absolutely not — most fatalities happen when unprotected rescuers enter the area. Without

air-supplied breathing equipment, you’ll be overcome just as fast. Always call for help and

follow your emergency response plan before attempting rescue.

Myth #6: H₂S is heavier than air, so it always stays low to the ground.

Mostly true, but not always safe to assume. Temperature, wind, and terrain can all cause the

gas to move unpredictably. That’s why atmospheric testing must be done at multiple

heights and locations before anyone enters a confined space.

Myth #7: Small leaks of H₂S aren’t a big deal.

Even a small release can be deadly in the right conditions. H₂S builds up quickly in enclosed

or low-lying areas, reaching toxic levels in seconds. Treat every alarm or odour as serious

until proven otherwise.

Myth #8: H₂S is only dangerous at high concentrations.

Even low concentrations can irritate your eyes and lungs and cause fatigue or nausea.

Prolonged exposure to lower levels adds up over time, increasing health risks. The goal is

zero exposure — not "safe enough"

Myth #9: A dust mask or bandana is enough protection from H₂S.

False — H₂S passes straight through simple filters and cloth masks. Only approved air-

supplied respirators or SCBA gear provide protection. If your PPE doesn’t supply clean air, it

won’t save you.

Myth #10: Once the alarm stops, it’s safe to go back in immediately.

Not necessarily — H₂S can linger in low spots or re-enter through vents and drains. Always

wait for safety personnel to test and clear the area. A quick re-entry without confirmation is

a common cause of secondary exposure.

Myth #11: H₂S monitors only need to be checked once a year.

That’s a dangerous assumption. Monitors must be bump-tested and calibrated regularly to

ensure they’re actually working. A detector that hasn’t been tested might as well not be

there.

Myth #12: H₂S training is only for people who work directly with oil wells.

Wrong — many other industries have H₂S exposure potential, from waste management to

food processing. Even a maintenance worker entering a sump or pit can be at risk. If there’s

any chance of H₂S, there should be training.

Myth #13: You can tell how bad the H₂S level is by how it smells.

Completely false. The gas deadens your sense of smell quickly, and odour intensity doesn’t

match concentration. Some of the most lethal levels have no detectable smell at all.

Myth #14: If you’ve worked around H₂S for years, you’ll know when it’s

dangerous.

Experience helps, but H₂S doesn’t care how long you’ve been in the industry. Veteran

workers are often the ones who take risks because they 'know the job.' The safest workers

follow procedures every time — no exceptions.

Myth #15: If someone collapses from H₂S, CPR won’t help.

That’s not true — if the area is safe and the rescuer is protected, CPR can absolutely save a

life. H₂S affects breathing and the nervous system, so rapid intervention is critical. Training

and quick response make the difference between rescue and recovery.

Myth #16: H₂S alarms always mean an emergency evacuation.

Not always — alarms are set at different thresholds to warn you before conditions become

critical. A low-level alarm means it’s time to assess and prepare, while a high-level alarm

requires immediate evacuation. Knowing the difference can save time and lives.

Myth #17: H₂S dissipates quickly outdoors, so it’s not a big deal.

It can disperse, but wind direction and terrain can trap it in pockets. Workers have been

overcome in open areas where the gas pooled in low ground. Always test and monitor

before assuming it’s safe.

Book your next H₂S Alive or refresher course in Cochrane today !