According to an update (PDF) issued Aug. 13, investigators for the Chemical Safety and Hazard Investigation Board have determined the sequence of events leading up to the hydrogen sulfide release that caused the deaths of two workers on April 22, 2026. The incident occurred during the decommissioning of the Catalyst Refiners Inc. facility, which conducted silver and ethylene oxide catalyst refining operations in Kanawha County, West Virginia.

CSB found that Catalyst Refiners no longer conducted silver reclamation operations by the time of the incident, but the facility’s wastewater treatment system was still functional. The decommissioning process involved the disposal of chemicals used in the silver reclamation process, including nitric acid and two proprietary chemicals. CSB identifies these as A-50, “a proprietary calcium chloride solution used as a coagulant,” and M-2000A, “a proprietary sodium trithiocarbonate solution used as a metal precipitant.”

On the day of the incident, workers pumped approximately 80 gallons of A-50 and 275 gallons of M-2000A into a wastewater receiving tank, then began to pump diluted nitric acid into the same tank. The employees observed a fog forming over the tank. The worker operating the pump stopped the flow of nitric acid, left the area, and briefly lost consciousness. A supervisor notified of the issue entered the tank area and also lost consciousness.

Two other workers not involved with the chemical transfer then entered the tank area. One of them rescued the unconscious supervisor, who subsequently recovered, as did the employee tasked with pump operation. But both of the workers who subsequently entered the tank area were overcome by the released vapors and later died from their injuries.

CSB’s update notes that Catalyst Refiners did not have a written procedure for disposing of A-50, M-2000A, and nitric acid through the wastewater treatment system. The facility had four full-face respirators on site, but not all were equipped with filters that would protect wearers from hydrogen sulfide. Workers told CSB that respirators were no longer required at the facility while it was being decommissioned, and Catalyst Refiners did not provide employees or contractors with personal gas monitors or require their use.

In addition to the two workers killed, 22 workers and first responders were decontaminated on site, and 18 were transported to medical facilities. State and national news outlets reported that local officials temporarily closed nearby roads and issued shelter-in-place orders, while agents of EPA and the West Virginia Department of Environmental Protection conducted monitoring and oversaw cleanup. CSB’s investigation will continue to assess chemical hazards and incompatibilities, decommissioning hazards, chemical disposal procedures, personal protective equipment, atmospheric monitoring, and corporate governance and oversight.

More information can be found in CSB’s Aug. 13 news release. The agency’s complete findings, analyses, and recommendations will be published in its final investigation report.

In March, NIOSH published a new fact sheet (PDF) on assessing the shelf lives of filtering facepiece respirators (FFRs). Although the agency does not currently require providers of approved FFRs to designate shelf lives for their products, a recent NIOSH study has “noted numerous challenges that the PPE community experiences when trying to locate FFR shelf life information,” the fact sheet states.

According to the fact sheet, respiratory protection program (RPP) and stockpile managers may not be certain whether a product can be used when information about shelf life is absent or difficult to find. NIOSH recommends that users contact the approval holder to inquire about the equipment’s shelf life. Users will first need to identify the FFR’s approval, model or part, and lot numbers, which may be found on respirator units, packaging, or approval labels.

Shelf life information, when determined, should be incorporated into users’ RPPs, stockpile documentation, and other procedures. To ensure that FFRs are used within their recommended shelf lives, RPP managers may employ a “first-in, first-out” approach in which FFRs that are purchased first are used first. Regardless of shelf life information, the fact sheet recommends users replace FFRs that are damaged, soiled, wet, or difficult to breathe through, as required by OSHA’s respiratory protection standard.

The fact sheet is part of a series titled “Personal Protective Equipment Conformity Assessment Studies and Evaluations Notes” or “PPE CASE Notes,” which aims to inform respirator users about common themes or trends identified by NIOSH through processes related to agency-approved respirators. NIOSH’s website provides more information, as well as a link to download the new fact sheet.

The 15th Report on Carcinogens, a congressionally-mandated publication of the U.S. Department of Health and Human Services National Toxicology Program (NTP), was released in December and includes eight new substances: the flame-retardant chemical antimony trioxide, chronic infection with the bacterium Helicobacter pylori (H. pylori), and six haloacetic acids found as water disinfection byproducts. With the exception of chronic infection with H. pylori, all of the new substances are listed as “reasonably anticipated to be a human carcinogen.” Chronic infection with H. pylori, which colonizes in the stomach and can cause gastritis and peptic ulcers, is listed as “known to be a human carcinogen.” According to NTP, chronic infection with the bacterium may lead to stomach cancer and a rare type of stomach lymphoma.

Antimony trioxide is a component of flame retardants used in consumer products including plastics and textiles. The highest exposure to the chemical occurs among workers who produce antimony trioxide or use it to make flame retardants. NTP notes that other people may be exposed to antimony trioxide by breathing outdoor air contaminated with the chemical or dust from the wear and tear of products treated with flame retardants.

The six haloacetic acids found as water disinfection byproducts listed in the 15th Report on Carcinogens include bromochloroacetic acid, bromodichloroacetic acid, chlorodibromoacetic acid, dibromoacetic acid, dichloroacetic acid, and tribromoacetic acid. Haloacetic acids “are formed during the disinfection of water from a reaction between the chlorine-based disinfection agents and organic matter in the source water,” NTP explains.

The 15th Report on Carcinogens and related materials can be found on NTP’s website.

A document published this month by NIOSH describes how to implement field-based monitoring for respirable crystalline silica using portable Fourier transform infrared spectroscopy (FTIR). The publication is primarily intended for industrial hygienists and allied professionals who have health and safety responsibilities within the mining industry, though NIOSH states that IHs working in other industries may also find it useful. According to the agency, the document is written for users with experience in respirable dust or respirable crystalline silica exposure assessment who do not necessarily have specialized training in analytical techniques. AIHA member Emanuele Cauda, PhD, co-director of the NIOSH Center for Direct Reading and Sensor Technologies, is a coauthor of the new publication.

“When used appropriately, field-based monitoring for [respirable crystalline silica] enables the timely evaluation of workplace exposure to crystalline silica and can be a valuable component of successful RCS control strategies,” the document explains. “The accuracy of results obtained via field-based monitoring are reliant upon field conditions as well as upon the conscientious sampling and analysis by the user.”

The new document includes instructions for setting up the equipment and software required for field-based respirable crystalline silica monitoring; technical details of the monitoring method; quality assurance procedures to ensure consistent data; and examples and case studies related to the use of different types of samplers in conjunction with field-based monitoring. Appendices include links to additional resources, operational checklists for field-based monitoring, and a comparison of FTIR data obtained using different methods or parameters.

“Direct-on-Filter Analysis for Respirable Crystalline Silica Using a Portable FTIR Instrument” is freely available to download as a PDF from the NIOSH website.

The occupational health and safety profession includes many sub-disciplines, including occupational hygienists.  Currently there are no Canadian jurisdictions that legally regulate occupational hygienists. Consequently, anyone can call themselves an occupational hygienist and offer such services, some have the required skills, knowledge, and training to protect workers, others do not, which can put workers at risk.  The new Alberta Society of Health and Safety Professionals (ASHSP) is a provincial society aimed at regulating occupational health and safety professionals in Alberta, including occupational hygienists.   We need Alberta Certified Industrial Hygienists, Registered Occupational Hygienists, Registered Occupational Hygiene Technologists, and anyone with the intention of seeking these professional designations to buy a ASHSP membership and help us make this a reality.  We are tired of talking about “licensing occupational hygienists” in Alberta, it is time for action.  All ASHSP members are invited to the ASHSP Annual General Meeting:

www.ashsp.ca

April 28^th, 2018

1:30 pm – 4:30 pm

University of Alberta, Lister Centre-Aurora Room

Located at 87 Avenue and 116 Street, Edmonton, Alberta