Fossil fuels are largely responsible for powering the vehicles, tools, appliances, and equipment that we use today, making oil and gas one of the most important industries in the world. However, it's not easy to work at these oil and gas refineries.

In addition to being subject to difficult and demanding conditions, workers are often also subject to hazardous gases. One such is hydrogen sulfide, or H2S, a common byproduct in these environments - yet one that's extremely dangerous in high concentrations.

In this post, we'll discuss more about how hydrogen sulfide is produced, where it's typically found in oil and gas refineries, and H2S PPE requirements to keep workers safe. Here's a closer look at what you need to know about H2S hazards and controls:

Hydrogen Sulfide 101

Also known as swamp gas, sewer gas, stink damp, or sour damp, hydrogen sulfide is produced naturally in sewers, manure pits, well water, volcanoes, and oil and gas wells. It's colorless, but easily recognizable thanks to its pungent, rotten egg-like scent at smaller concentrations. It's also flammable and highly toxic, especially for workers exposed in confined spaces.

H2S is commonly produced in a variety of industries. In addition to the oil and gas sectors, it's also commonly produced in mining environments, pulp and paper processing, and rayon manufacturing. Heavier than air, it collects in low-lying and enclosed spaces - and that's a big part of why it's so dangerous.

Effects on the Body

Exposure to hydrogen sulfide can have a range of different effects on the human body, with symptoms varying based on the level of exposure, duration of exposure and the type of work being done at the site of exposure. Some effects of lower-level exposure include:

  • Eye irritation
  • Dizziness
  • Headaches
  • Nausea
  • Weakness
  • Irritability

Exposure to H2S at higher concentrations can be extremely dangerous. Exposure to Hydrogen Sulfide at concentrations above 500 parts per million (ppm) can result in a "knockdown effect" where individuals suddenly become unconscious before seemingly appearing to recover. This knockdown effect can lead to a variety of long-term health issues, such as neurological problems, memory and motor problems, personality changes, hallucinations, and anosmia (the loss of sense of smell, either total or partial).

Other health effects linked to H2S exposure include convulsions, sleep apnea, insomnia and coma.

To help protect workers against exposure, OSHA has established permissible H2S exposure limits (PELs). These limits regulate the amount of a particular substance in the air. PELs are enforceable and are based on an eight-hour time-weighted average. The OSHA PEL for H2S is 20 ppm for an eight-hour shift and peak exposure is permitted at 50 ppm as long as it's for no more than 10 minutes in an eight-hour shift.

How Exposure Commonly Occurs

According to data from the U.S. Bureau of Labor Statistics, hydrogen sulfide exposure was responsible for 46 worker deaths between 2011 and 2017 - making it one of the leading causes of gas inhalation deaths in the country. Exposure - and potentially death - occurs due to the behavior of H2S. For instance:

  • It's highly flammable and toxic.
  • Since it's heavier than air, it can travel and build up along the ground and in low-lying areas.
  • Its rotten egg smell is a warning sign, but many workers report not smelling it any longer following periods of exposure at either low or high concentrations.
  • It can completely overcome workers who are unprepared or unaware of the danger.

Fatalities from H2S exposure often occur due to a lack of gas monitoring equipment, a lack of proper PPE and a lack of education on the dangers of H2S exposure and how to properly protect oneself.

Common Exposure Spaces in Oil and Gas

In the oil and gas industry specifically, exposure is common in a variety of spaces. These include:

  • Sour gas fields: These are fields high in acidic gases, such as Hydrogen Sulfide and Carbon Dioxide, once considered undesirable for mining. Sour gas, by definition, is described as any gas containing significant H2S, which is thereby removed in the creation of natural gas.
  • Natural gas deposits
  • Maintenance work, particularly on pipelines or hatches in enclosed or confined spaces
  • Operation within tankers or in other miscellaneous confined spaces in oil and gas environments

Why H2S Will Continue to Require Proper Management

Despite many of the dangers discussed regarding H2S exposure, it's likely to continue to be a problem that needs to be properly managed in the oil and gas industry and other industrial environments. Here's why:

  • New methods of extraction: Fracking, deep sea mining and deepwater drilling are becoming more popular. Unfortunately, the risk of H2S exposure is lesser known in these newer types of extraction - and until more information is gathered on worker risks in these environments, the proper PPE must be worn to prevent and decrease potential exposure.
  • High demand for natural gas: According to reports, the annual average demand for natural gas is expected to grow at an annual average of about 1 percent through at least 2025. With demand increasing, the search for new sources of gas becomes crucial. Combined with sour gas field processing, the oil and gas industry is exploring a variety of avenues to keep up with demand.
  • Solo workers: Much of the work in the oil and gas industry is solo work - and it's also these workers that are at the greatest risk of H2S exposure. Lack of familiarity with H2S preventative measures and the tendency for lone workers to "go rogue" when they're not being watched makes for a bad combination. Solo workers being unaware of H2S exposure and experiencing a "knockdown" can be very dangerous.

How to Protect Yourself from H2S

The good news is that it's not difficult to prevent H2S exposure - even in the environments most prone to Hydrogen Sulfide buildup. For starters, gas monitoring and detection technology should be administered on every site to properly gauge levels and monitor air quality. But this monitoring technology should also be complemented with the right PPE.

For instance, workers should wear respirators to ensure that they're not breathing in any of the H2S gas. Make sure the respirator is a purifying one with specialized cartridges. A full-face respirator can also offer eye protection and prevent eye irritation from exposure. Those working at high concentrations of H2S (100 ppm and above) should wear a full-face pressure-demand self-contained breathing apparatus.

Hydrogen Sulfide exposure is no joke - and exposure can be dangerous and even deadly. When it comes to any profession, worker safety is paramount. Take the time now to review H2S exposure limits, hazards and controls, and PPE requirements to ensure your work site is kept safe.