Safeguarding workers from low H2S exposure

MSA Safety's ALTAIR io™ 4 Connected Gas Detector offers enhanced detection of low-concentration hydrogen sulphide, improving worker safety and ensuring compliance in industries like oil, gas, wastewater, and steel production

HYDROGEN sulphide (H2S) gas can be fatal at high concentrations. But even low concentrations can cause health issues, particularly with prolonged exposure. So how can you best protect workers and minimise downtime?

WHAT IS H2S GAS?

Hydrogen sulphide is a highly flammable, toxic and corrosive gas found in several industries including oil and gas, wastewater and chemical processing.

It's sometimes called 'sour gas', 'sewer gas' or 'stink damp' because of the way it smells, like rotten eggs.

However, H2S can't reliably be detected by smell as it quickly deadens the sense of smell (a process known as 'olfactory desensitisation or fatigue').

HOW DANGEROUS IS H2S?

Exposure to high levels of H2S can be fatal, leading to loss of breathing, coma, seizures and death. It's the second most common cause of fatal gas inhalation exposure in the workplace, second only to carbon monoxide.

But H2S can also be harmful at low concentration levels, causing headaches, dizziness, nausea, breathing difficulties and a sore throat. These health impacts can become more serious with prolonged exposure.

The health impacts of H2S depend on how much is inhaled and for how long. The recommended exposure limit set by NIOSH (the US National Institute for Occupational Safety and Health) for 10 minutes is 10 ppm.

However, some US states have developed ambient air standards for H2S well below OSHA and NIOSH standards due to concerns about health risks from chronic exposure.

For longer exposures to H2S, the recommended limits are a lot lower. For example, if you’re exposed for up to 24 hours, the World Health Organisation (WHO) recommends a maximum exposure of 0.1 ppm.