Extreme heat kills hundreds of people in the US each year. According to the US Centers for Disease Control and Prevention, more people perish this way than die as a result of tornadoes, hurricanes, floods and lightning combined.

Summers in North America are hot, often with heat waves in one or more parts of the US. Regions east of the Rockies tend to experience both high temperatures and high humidity, although some of the worst heat waves have been catastrophically dry.

This year already, a heat wave has caused the death of one man and hospitalized at least another 40 in Las Vegas, where temperatures shot up to 115 degrees one Saturday afternoon at the end of June.

And people who work outdoors are particularly at risk of heat illness in the summer.

In 2011, the Occupational Safety and Health Administration (OSHA) and the National Oceanic and Atmospheric Administration (NOAA) in the US launched the Campaign to Prevent Heat Illness In Outdoor Workers.

Dr. David Michaels, assistant secretary of labor for OSHA, says in a taped interview on the OSHA website that “each year, heat sickens thousands of outdoor workers. And heat can also kill.”

Last year alone, at least 30 outdoor workers in the US died as a result of heat exposure, says Michaels.

Heat illness develops when the body’s natural ability to cool itself by sweating is not enough. This is especially a problem when heat is combined with high humidity. When this happens, body temperature can rise to dangerous levels if precautions aren’t taken.

The resulting illness ranges from heat rash and cramps to heat exhaustion and heat stroke, which can be fatal if not treated immediately.

The Campaign to Prevent Heat Illness In Outdoor Workers aims to educate outdoor workers and their employers about how to avoid heat illness.

The initiative offers various education and training resources, and emphasizes three words: water, rest, shade. In addition, the Campaign advises employers to ensure that during hot weather their outdoor workers:

  • Drink water often: at least every 15 minutes, even if not thirsty
  • Avoid alcohol and caffeine
  • Take frequent breaks in the shade and limit time in the heat.

Campaign literature also advises employers to give new workers lighter duties until they have had time to adjust to the heat. The same applies to workers who have been away from work for a week or more.

The initiative has so far distributed nearly half a million fact sheets, posters, quick cards, guides and wallet cards, and it has reached more than 7 million people.

There is also a section on the website that advises employers on how to develop a heat illness prevention plan.

More recently, the Campaign has developed a Heat Safety App that allows workers and supervisors to calculate the heat index for their work site.

Once the app calculates the heat index, it shows the risk level to outdoor workers. Then with a simple click, they can get reminders about the protective measures they should take for that particular risk level. For example, these could remind them about drinking enough fluids, taking regular rest breaks, plus planning for and knowing what to do in an emergency.

The app also includes reminders about adjusting workloads, how to spot the signs and symptoms of heat illness, and suggests how workers could keep an eye on each other for these signs and symptoms.

The app is free to download, is available for iPhone and Android, and there are versions in both Spanish and English. Or you can use it directly on the webpage.

Last month the CDC also issued advice on preparing for extreme summer heat.