The U.S. Department of Labor's Occupational Safety and Health Administration has announced the launch of its annual Campaign to Prevent Heat Illness in Outdoor Workers. For the fourth consecutive year, OSHA's campaign aims to raise awareness and educate workers and employers about the dangers of working in hot weather and provide resources and guidance to address these hazards.

Workers at particular risk are those in outdoor industries, such as agriculture, construction, landscaping and transportation.

However, cleaning professionals may also be at risk of overheating while performing regular cleaning tasks such as emptying trash, sweeping parking lots, or washing windows outdoors — or during duties in facilities with inadequate air cooling systems.

"Heat-related illnesses can be fatal, and employers are responsible for keeping workers safe," said U.S. Secretary of Labor, Thomas E. Perez. "Employers can take a few easy steps to save lives, including scheduling frequent water breaks, providing shade and allowing ample time to rest."

Thousands of employees become sick each year and many die from working in the heat. In 2012, there were 31 heat-related worker deaths and 4,120 heat-related worker illnesses. Labor-intensive activities in hot weather can raise body temperatures beyond the level that normally can be cooled by sweating. Heat illness initially may manifest as heat rash or heat cramps, but can quickly escalate to heat exhaustion and then heat stroke if simple preventative measures are not followed. Heat illness disproportionately affects those who have not built up a tolerance to heat (acclimatization), and it is especially dangerous for new and temporary workers.

"Acclimatization is a physical change that the body undergoes to build tolerance to heat, and it is a critical part of preventing heat illnesses and fatalities," said Dr. David Michaels, assistant secretary of labor for occupational safety and health. "Over the past three years, lack of acclimatization was the cause in 74 percent of heat-related citations issued. Employers have a responsibility to provide workplaces that are safe from recognized hazards, including outdoor heat."

Last year, OSHA issued 11 heat-related citations. In some of these cases, the employer and staffing agency were cited because they involved temporary workers.

In preparation of the summer season, OSHA has released a free application for mobile devices that enables workers and supervisors to monitor the heat index at their work sites. The app displays a risk level for workers based on the heat index, as well as reminders about protective measures that should be taken at that risk level.

OSHA has also developed heat illness educational materials in English and Spanish, as well as a curriculum to be used for workplace training, also available in both English and Spanish. Additionally, a Web page provides information and resources on heat illness - including how to prevent it and what to do in case of an emergency - for workers and employers. The page is available, here.