“The fact is the media never gets off the interstate unless there’s a major explosion.”  — Jim Harrison

On Friday, March 24, 2023, shortly before 5 pm local time, an explosion leveled the R.M. Palmer Company chocolate factory in West Reading, Pennsylvania, killing seven workers.

How does a chocolate factory explode? What are the explosive hazards, and what can the rest of us in the process industries learn from this incident?


There was a lot of early conjecture about what could have caused a massive explosion capable of leveling a building and killing seven people. Process safety professionals speculated that it could have been sugar dust in a combustible dust explosion. A heated pressure vessel used to melt chocolate overheating and resulting in a pressure vessel explosion (PVE). A boiler failure.

The involved agencies and the press are to be congratulated on their restraint in discussing and reporting on the explosion. Initial reporting focused on the dead and missing, and as one journalist put it, “the cause of the explosion remained under investigation.” The public hates that. They want answers, and they want them now.

However, there was early reporting that workers had complained about smelling gas at the plant. Not just on Friday, but for an extended period before then. So, early speculation from those not operating from an armchair was that the explosion was due to a gas leak. But UGI, the utility company that supplied natural gas to the plant, stated that it had not received any reports of a gas leak at the plant.

The NTSB is Investigating

In addition to the Pennsylvania State Police Fire Marshal, who is investigating the explosion, the National Transportation Safety Board opened an investigation on Tuesday, March 28. Why is the NTSB involved? Because pipelines are under the jurisdiction of the Department of Transportation, which means that there is growing belief that natural gas was the fuel for the explosion.

There is no indication that other federal agencies are investigating. Yet. The ATF is not there. Neither is the EPA or OSHA. (Pennsylvania doesn’t have a state-plan OSHA.) However, with seven worker fatalities, it wouldn’t be at all surprising to see OSHA open an investigation, especially given their philosophy that any worker fatality can be avoided by complying with all OSHA regulations.

Lawsuits have been Filed

Within a few days of the explosion, a neighbor filed a lawsuit against R.M. Palmer. Reporting indicates that Betty Wright’s lawsuit alleges that R.M. Palmer did not alert her that she was moving into a home where a “dangerous and explosive hazard…was present in or around her apartment which was in the zone of danger.”  Ms. Wright asserts that she was injured by the explosion and that her property was damaged. She wants $50,000+ in damages.

From a distance, it’s hard to judge her claims, but they seem plausible. Except for the claim that R.M. Palmer did not alert her that she was moving into an apartment where there was a “dangerous and explosive hazard.” Who considers the use of natural gas for heating as a dangerous and explosive hazard about which neighbors must be warned?

Natural Gas is a Hazard

Natural gas is a flammable gas. It wouldn’t be much use as a fuel otherwise. It is inherently hazardous. In a paper in the journal, Environmental Science and Technology, the authors estimate that there are 659,000 gas leaks per year. Not every leak leads to catastrophe, however. Others note that there are about 300 natural gas explosions per year that lead to death, severe injury, or property damage. The result of these catastrophic natural gas explosions, of which the West Reading explosion may be one, is that on average, about 15 people are killed per year.

On the other hand, electricity, the logical substitute for natural gas, is also hazardous. In a 2022 NFPA paper, Richard Campbell observes that there around 47,000 electrical fires per year that required fire department response, and the average number of civilian deaths is almost 400 per year.

Natural Gas and PSM

The Process Safety Management (PSM) Standard (29 CFR 1910.119), has a threshold quantity for flammable gases of 10,000 pounds. When we’re using natural gas for heating, it is unlikely that we exceed that threshold quantity. But even if we did, the PSM standard has an explicit exception for hydrocarbons used as fuels. Using natural gas for heating is not covered under PSM. So, there is no regulatory requirement for process safety information, for process hazard analysis, or for a mechanical integrity program when it comes to gas heating.

Not Helpless

Nothing about the explosion in West Reading suggests that R.M. Palmer was covered under the PSM Standard. That doesn’t mean, however, that facilities using natural gas for heating must simply accept the already low probability that theirs is a facility that will experience a natural gas explosion. There are things that can be done to improve the odds of avoiding a natural gas explosion, even without a mechanical integrity specialist at the site.

  1. Do an annual inspection of gas lines.
  2. Check for the strong smell of the odorant that utility companies add to natural gas.
  3. Listen for the hiss of leaking gas.
  4. Spray the line with a soap solution, especially at joints and fittings, and look for the bubbles of a leak.
  5. Contact your gas utility company immediately when you suspect a leak.

If You Smell Something, Say Something

The loss of life at R.M. Palmer was tragic. No one should die on the job. Employers are responsible for providing a workplace free from recognized hazards that cause fatalities or serious injuries. Natural gas is a recognized hazard, but so is anything that could be used as a substitute. It’s not reasonable to decide that the thing to do is to eliminate natural gas as a fuel, but it is reasonable for us to recognize natural gas for the hazard it is and act accordingly.

If you haven’t done it for years, or ever, go inspect your natural gas lines. And, to paraphrase the Department of Homeland Security, “If you smell something, say something.”


  • Mike Schmidt

    With a career in the CPI that began in 1977 with Union Carbide, Mike was profoundly impacted by the 1984 tragedy in Bhopal and has been working on process safety ever since.