In response to a rapid rise in deaths of cellphone tower workers, the Occupational Safety & Health Administration (OSHA, part of the US Department of Labor) has sent a new letter this week to mobile firms to express its concern. OSHA also notified the companies that it had re-organized relevant regulations and other information in a new website, which was published Tuesday.

According to the agency, 13 worker fatalities occurred in 2013, “more than in the previous two years combined.” OSHA added, “This disturbing trend appears to be continuing, with... four worker deaths occurring in the first five weeks of 2014.”

In 2012, an investigation by ProPublica found that “between 2003 and 2011, 50 climbers died working on cell sites, more than half of the nearly 100 who were killed on communications towers.”

ProPublica reported at the time:

We found that in accident after accident, deadly missteps often resulted because climbers were shoddily equipped or received little training before being sent up hundreds of feet. To satisfy demands from carriers or large contractors, tower hands sometimes worked overnight or in dangerous conditions. One carrier, AT&T, had more fatalities on its jobs than its three closest competitors combined, our reporting revealed. Fifteen climbers died on jobs for AT&T since 2003. Over the same period, five climbers died on T-Mobile jobs, two died on Verizon jobs, and one died on a job for Sprint.

"Tower worker deaths cannot be the price we pay for increased wireless communication," Dr. David Michaels, assistant secretary of labor for OSHA, wrote in a statement on Tuesday. "Employers and cell tower owners and operators must do everything possible to stop these senseless, preventable tragedies."