It's hot out — and while the extreme heat can be a hassle for those with office jobs, it can be a real health risk for those who work outside.

The Occupational Safety and Health Administration (OSHA) is leading a summertime effort to help keep workers informed of those risks.

Judy Posusney, an assistant director at OSHA's Philadelphia office, says the main thing is this: "Water, rest and shade. If people can remember those three things, they are key."

Helpful app

A centerpiece of OSHA's campaign is a new smartphone app that can calculate the current heat index based on weather readings for where you're standing (screengrab). The app lists diagrams and guidelines depending on just how hot it is.

Tuesday's highest heat index of a dry 96 degrees put the risk level at a mere "moderate," but construction workers in Camden, N.J., didn't need an app to tell them what precautions to take.

"No, not at all. I can feel it outside," said Jean Black, with the Napp-Grecco Company of Newark, N.J. "You can feel the temperature, obviously, and you know what you basically need to do."

Black and a crew of fellow workers were checking on a pipeline near the port of Camden under the midday sun.

"We're drinking a lot of water. We're making sure that we stay hydrated," Black said, water bottle in hand. "When it's a hot day, you never know if you're actually gonna go down. So if you don't keep that water in your system, it's a little bit of a problem."

The job also had a commercial dive team on site. Steve Gardner of The Castle Group was packing up the wetsuits. 

"It's nice being in the water," Gardner said. "It's better than being on land."

He too said water (the drinking kind) is key.

As for the new app, Gardner says he'll be fine without it.

"We got the local weather, we got, you know, just being a human," he said. "If it's hot out, you know it's hot."

Back at OSHA, Posusney said it's all about finding new ways to help people working in the brutal heat. The goal is to inform, so workers can avoid the serious dangers of heat stress.

Aside from the app and a website, there's also a hotline, 800-321-OSHA, for worker concerns.