Construction is one of the most dangerous professions, with one in five worker fatalities in 2018 occurring within the industry. The dangers of a construction site extend beyond the fatal four dangers reported by OSHA (falls, electrocution, struck-by-objects and caught-in-between) to those that cannot be easily spotted. Known as the silent killer, Hydrogen Sulfide, commonly referred to as H2S or sour gas, is the second most common cause of workplace gas inhalation fatalities following carbon monoxide. The colorless, flammable gas is naturally produced by the decomposition of organic material and is also emitted as a by-product of many industrial processes.

Often collecting in low-lying and enclosed, poorly ventilated spaces, construction workers surveying and performing tasks within basements, caves, tunnels, manholes, landfills, underground utility vaults, marshy areas and sewer lines, as well as those working with asphalt, can easily and quickly be overpowered by exposure to the gas. Symptoms vary according to exposure—at lower exposure rates (0.001 - 1.5 ppm), H2S is often first detected as a rotten egg smell, while at higher rates (3 - 5 ppm), the odor is more offensive. According to OSHA, workers who experience prolonged exposure to H2S may notice physical symptoms, including but not limited to:

• nausea, tearing of the eyes, headaches, loss of sleep (2 - 5 ppm);
• possible fatigue, loss of appetite, headache, irritability, poor memory and dizziness (20 ppm);
• slight conjunctivitis and respiratory tract irritation, loss of smell/olfactory paralysis, altered breathing (50 - 100 ppm);
• collapsing, serious eye damage and death within 30-60 minutes (500 - 700 ppm);
• rapid unconsciousness within one or two breaths and death within minutes (700 - 1,000 ppm); and
• death within moments (1,000 - 2,000 ppm).

To enhance jobsite safety in the construction industry and others, OSHA and the American National Standards Institute, in addition to other federal and independent agencies, have set allowable exposure levels and specific practices to mitigate the hazards of H2S. Although ANSI/ASSE has recommendations in place regarding which workers need to be trained on the hazards of H2S, any personnel working at or visiting a jobsite potentially containing the deadly gas should receive proper training to prevent job-related injuries and death.

Proper worker safety training and risk management are the best methods for preventing injury, illness and workplace deaths related to H2S. By implementing annual retraining, construction companies can ensure those working or visiting a location where H2S could be present have the knowledge to recognize, avoid and contain the deadly gas. Annual training is the most effective method for employers to guarantee its workers have the foundation of knowledge needed to continuously address high risk situations. In fact according to research, the retention of 75% of new information is forgotten after six days if it isn’t applied.

By mandating that workers’ training certifications for H2S be updated annually, construction companies can ensure that workers are sufficiently trained. Insufficient training can lead to increased jobsite hazards that result in costly fines for operators and contractors who fail to ensure workers are properly prepared. Over the past several years, OSHA has repeatedly cited employers across industries for knowingly exposing workers to H2S dangers, causing companies to pay anywhere from tens of thousands to millions of dollars in penalties.

Current H2S safety standards require a certain segment of training to be conducted by a qualified instructor certified by a master trainer. During the training session, the instructor will cover key topics, including:

• understanding H2S levels and associated health risks;
• use of administrative controls, detection and monitoring methods; and
• emergency response and first aid.

Unlike in years past, employees can no longer complete a condensed refresher training course for their annual training requirement. Staying up-to-date on training standards creates a safer and more productive environment for construction workers. Injuries and fatalities related to H2S are preventable by ensuring employees understand and are following the most up-to-date safety standards and procedures at every H2S jobsite.