The American National Standards Institute's ANSI/ASSE Z390.1—2017 provides standards for products, services, processes, systems, and personnel in the United States that relates to the use of hydrogen sulfide (H2S) in the workplace.

Hydrogen sulfide is one of the leading causes of workplace gas inhalation deaths in the United States, and general federal safety standards for H2S aren't anything new. But these newly updated standards have become more specific and contain important clarifications employers need to know.

This article will give you an overview of some of the new clarifications and specifications so you can have a better understanding of your obligations.

Best Practices Safety Highlights

The most important thing employers need to know regarding best practices relating to H2S safety is that this gas is extremely flammable, deadly toxic at certain levels, and difficult to detect (it is both colorless and odorless). It is imperative that anyone with the potential for exposure to H2S be sufficiently trained to recognize and understand the hazards associated with this gas.

Meeting the new standards can get complicated, but it doesn't have to be that way. Working with industry professionals who understand the new standards and can help you address all specific and related compliance issues is the best way to ensure that you are following best practices.

Training Update

The new standards set forth robust training and instruction requirements for workers and visitors to the work site.

In the mid-1980s, an H2S certificate could be obtained by completing a class that could have lasted as little as 15 minutes. This training was often packaged in with other topics, meaning that instructors were unlikely to give workers an adequate understanding of hydrogen sulfide safety.

The updated ANSI standard vastly improves the training workers receive by specifying the appropriate duration for instruction. H2S course must now include a minimum of three to four hours of training.

The standard also addresses the issue of specific topics that need to be covered. The topics are designed to ensure that each worker understands the nature of the risks present on the job, how to address and mitigate them, and how to respond in the event of an emergency involving hydrogen sulfide exposure or the risk of exposure. H2S training should include:

  • Exercises and drills
  • Properties and characteristics of H2S
  • Identifying sources of hydrogen sulfide
  • Areas of potential exposure
  • Site-specific risk mitigation
  • Appropriate selection and use of personal protective equipment (PPE)
  • Rescue techniques and first aid procedures

The new standard also does away with different training levels, replacing it with a single level of training: H2S Certified. In a nutshell, workers are now either certified or not – period. The certification is valid for one year and workers need to take an annual certification refresher course.

While computer-based training is convenient and has some advantages, it is no longer an appropriate delivery mechanism for H2S training. The training must, instead, be in person and led by a qualified instructor. The H2S instructor must meet new requirements, with demonstrated competency of the detailed and larger curriculum that must be covered in the course. Instructors must themselves also be trained in person by a qualified instructor (for advice on in-person training, see 7 Superb Psychological Tactics for EHS Training).

Other Steps You Need to Take

The guidelines presented in the new standard are designed to give workers the fundamental knowledge they need to protect themselves from hydrogen sulfide exposure. But it is not the only standard that needs to be followed. It does not include the information required to satisfy the ANSI Z88.2 Practices for Respiratory Protection and OSHA Respiratory Protection 29CFR 1910.134. It also does not provide the site-specific information necessary to work at a particular facility. Government regulations (see OSHA Hazard Communication 29 CFR 1910.1200) specify mandatory requirements for training personnel who work with or around chemicals.

Employers and facilities where personnel may encounter H2S should perform their own assessments to determine appropriate safe exposure levels based on the advice of qualified safety professionals.

Visitors are not exempt from the initial and annual H2S training. Anyone that can be potentially exposed to this gas should complete the entire training course and have refresher training every year.


Hydrogen sulfide poisoning fatalities are reported every year in several different industries. With the new standards in place, we will hopefully see a reduction in the number of those affected. Working with industry professionals who understand compliance issues is the best course of action to reduce and mitigate risks related to H2S.