Nothing matters more when you’re on the job than safety.

Worker safety is the first responsibility of every employer, whether in private business or government.

If that seems self-evident and hardly necessary to say, we might normally agree. But then we encounter yet another case of workers unnecessarily being hurt, and we are reminded again that safety is not always the first priority in American business — not by any means.

EDITORIAL

On Thursday morning, 10 workers were hurt in an explosion at a water reclamation plant — a sewage plant — on Chicago’s far South Side. The explosion collapsed the roof of a building at the Calumet Water Reclamation Plant, at 400 E. 130th St.

Hundreds of thousands of pounds of concrete slammed down on the 10 workers. Eight were quickly rescued and sent to the hospital, but a ninth worker was pinned down for 20 minutes and a 10th was trapped for two hours. Fortunately, none of the injuries were life-threatening.

The city’s Office of Fire Investigations has determined that the explosion was set off by a torch used in an area with a significant amount of methane gas present.

It’s important, of course, to get to bottom of what went wrong. But as we were writing this editorial on Friday morning, we received a note from a Sun-Times reader that perfectly expressed a few related points we had hoped to make, such as the importance of the work that is done at water treatment plants.

So allow us to quote from Roberta Wood, a retired journeyman electrical instrument and testing mechanic who once worked at the plant:

“Sewage treatment isn’t prestigious, but it is perhaps the most important guarantor of the health of the people in the Chicago area, protecting millions from the deadly epidemics of typhoid fever and cholera that ravaged earlier populations.”

And we had hoped to stress how easy it is to ignore workplace safety until something goes terribly wrong.

Or, as Wood put it:

“This near tragedy should make every American who cares about working families give deep thought to how important worksite safety regulations are. Ironically, it’s the effectiveness of those regulations, and their rigorous enforcement, that means we don’t think about them till it’s too late.”

And we thought we should at least raise the question of whether a growing anti-union and pro-employer ethos, promoted by the likes of Gov. Bruce Rauner and President Donald Trump, might be diminishing concerns for safety at work.

Or, as Wood wrote:

“When we have a governor like Bruce Rauner who is openly at war with workers’ rights to organize and have a voice on the job, we have to ask if that promotes a devaluation of workers’ very lives.”

The Trump administration, Wood wrote — and we checked her facts — has withdrawn 469 proposed federal workplace health and safety regulations and delayed 393 more.

There is a myth that working conditions in the United States have improved so much in the last century — better pay and benefits and safer workplaces — that unions no longer are necessary and safety regulations should be eased.

Yet more than 5,000 American workers still are killed on the job each year — a huge improvement over the 13,000 annual deaths four decades ago, but still nothing to boast about. Employers in private industry also reported 2.9 million nonfatal workplace injuries and illnesses in 2016, the last year for which data is available.

When it comes to workers’ safety and well-being, paternalistic reassurances will never cut it. We’ll take union and hard-won regulator protections any day.

Allow us to give Wood the last word, because she’s earned it:

“This Labor Day weekend,” she wrote, “let’s honor workers and their families by reasserting the importance of preserving and enforcing health and safety both on the job and in the communities where working-class children live and go to school.”

Happy Labor Day to all.

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