“Human Error?” Don’t Believe Everything Your Read

Dense cloud of chlorine threatens community near chemical plant. Chemical Safety Board issues preliminary findings of investigation of a chemical release that sent more than 140 people to the hospital last year.  AP headlines scream out “Feds: Human error, labeling led to chemical cloud in Kansas.”

Every time I read the words “human error” connected to any kind of industrial or chemical disaster, little alarm bells go off in my head.  And usually those little alarm bells are correct. In this case, for example, nowhere in the preliminary CSB Findings of last year’s Chemical Release at MGPI Industries do the words “human error” appear.

A superficial reading of the AP article about the events that led to the chemical release might indicate human error:

The chemical release from MGP Ingredients in Atchison, Kansas, occurred when a delivery truck driver inadvertently unloaded sulfuric acid into a [Harcros] tank that contained sodium hypochlorite. The chemical reaction produced chlorine gas, which drifted for nearly 6 miles over the Atchison region before dissipating after about four hours

Dumb guy hooked up the hose to the wrong pipe? Probably need to fire him. Problem solved? Case closed?  Not quite.

What the CSB actually found was a number of procedure problems and design deficiencies:

• sodium hypochlorite fill line and the sulfuric acid fill line were both open
• The line used to transfer sulfuric acid looked similar to the sodium hypochlorite line
• the two lines were located in close proximity
• emergency shutdown mechanisms were not in place or were not actuated from either a remote location at the facility or in the truck.
• The lines were poorly labeled
• Neither  MGPI nor Harcros followed  internal procedures for unloading operations.

But the fact is that they guy did hook up the hose to the wrong pipe. So why isn’t that “human error?”

It is, but humans, being humans, always make errors. Not paying attention, bad sleep last night, fight with the spouse or kids this morning, long day, boss just yelled at you, 15 more deliveries to make and you’re running late.  Some or all of the above make human beings fallible. Add to that a confusing layout, poor procedures and lousy labeling. That’s why systems that are well engineered for safety take into account that fallible humans are running them and seek to engineer or design human error out of the process — and have good emergency procedures if all else fails.

The CSB hasn’t issued recommendations yet. But I would predict that they will refer to existing industry  best practices to recommend changes in design (fill lines that look different, perhaps have different connectors, located at a distance apart), improved procedures for unlocking fill lines (and training on those procedures), fail-safe emergency shut-down mechanisms.

The problem with labeling the whole thing “human error” is that it leads to the assumption that you can just replace that worker with a different, perhaps more conscientious worker, and everything will be fine. The problem is that if the procedures are bad, the fill lines aren’t well labeled and look the same and are located near each other, and the emergency shutdown mechanisms still don’t work — then the next worker on the job will have the same problem.

So beware of headlines bearing messages of “human error.” The safety of our workplaces and  communities shouldn’t depend on humans never making mistakes.