The sweaty dog days of summer are not only uncomfortable, but can create health-threatening conditions for outdoor workers without proper safety strategies, experts say.

"We're like cars," said Norman Harris, a certified industrial hygienist with the PMA Insurance Group in Blue Bell, Pa. "Our circulatory system is our radiator cooling system. We let that radiator run dry, we're more likely to overheat."

Although drinking plenty of water in hot weather seems like common sense, dehydration and overheating contributed to more than 2,600 heat-related workplace illnesses or injuries in 2005, according to the Bureau of Labor Statistics.

Heat-illness prevention runs the gamut from providing water to using advanced technology to calculate the work-to-rest ratio. Steel workers, for example, often are weighed before and after shifts to monitor any excessive water loss.

Standard good practices include providing ample water and shade breaks.

"Industrial hygienists have some very detailed tactics on how to prevent heat illness," said Ken Martino, Specialty Risk Services' senior vp in Hartford, Conn. One of these instruments is a wet-bulb globe thermometer, which measures the effect of high temperatures, humidity and solar radiation on people and helps industrial hygienists determine safe exposure levels for workers in adverse weather.

Safety consultants recommend several steps to keep workers safe when the mercury rises. Mr. Martino said managers should monitor weather forecasts and arrange the work accordingly. "Make the schedule more flexible. Start earlier in the day, have breaks in the peak period or start later in the day." When working outdoors, employees should don hats and light-colored clothing. Some workers opt to wrap their heads in wet towels. Frequent drinking breaks--Gatorade and water instead of caffeinated drinks--are essential to replace water the body loses through sweating.

Some employees, such as older, overweight or diabetic individuals, are more vulnerable to the elements. "Being overweight is probably the worst thing," said Mr. Harris of PMA. Overweight people, who are already at risk of not being able to regulate their body heat, take longer to acclimate to hot weather, he said.

Supervisors should adjust these at-risk employees' schedules or work conditions accordingly.

Develop a plan

A contingency plan is vital should heat illness strike, Mr. Martino said. "One part is training supervisors in knowing signs. The other part is having a plan once you've identified that person (as sick). Know the EMS number or where the closest clinic is and what you're going to do for that person."

Acclimation to hot weather is a "big factor" for the physically fit, as well, Mr. Harris said. It takes up to two weeks for a person new to outdoor work to get used to the temperature.

Many outdoor workers, such as landscaping crews, can self-pace their hydration and cool-down breaks. "My guys are pretty much on their own and they take breaks when they need them," said Kevin Crotchfelt, owner of Sun Valley, a property maintenance company in Scottsdale, Ariz. "I supply them with as much water, ice and Gatorade product as they need. I leave it up to them; if they feel tired, they take a break."

But in other industries, such as those involving machinery, self-pacing is not an option.

"Where you get into trouble is where you can't take a break because there's not enough alternative workers to take your place," Mr. Harris said. "The worker feels obligated to continue to work at the rate of the machine." Road paving is such a case, he said. In this area of work, managers should staff enough alternates so workers can be rotated between hot work areas and shaded break sites.

And, in most circumstances, those shaded break areas should have large fans to cool workers, Mr. Harris said. But when temperatures climb past 95 degrees, the increased air velocity past the skin actually makes the individual hotter. "You just don't want to blindly think air movement helps the situation," he said.

These heat safety precautions aren't just for construction crews, factory workers or groundskeepers. The 60,000 employees at Disney World in Orlando, Fla., also follow guidelines as they work outside in the summer. Character performers in heavy costumes spend less time on stage and more time in air conditioned break rooms, a spokeswoman said. Costume designers have also changed the costumes to increase air flow.

Employees manning food stands in the park work in the shade or beneath umbrellas. And safety tips, like hydration and recognizing the signs of heat illness, are spread through employee meetings, information in break rooms and through newsletters.

The Occupational Safety and Health Administration has no specific regulations regarding work-related heat illness, but the federal agency does distribute tips on how employees can stay safe (see box).

In 2006 California's OSHA became the first state to single out the issue with new guidelines requiring employers to train supervisors and workers in heat illness awareness. The new rules came after 13 heat-related fatalities in 2005.

Often the biggest obstacle is not creating heat safety plans, but making sure that employees change their behavior and that policies are followed on the work site.

"You have to sell it to people who say, 'I've worked in the heat all my life,"' Mr. Martino said. One strategy is for managers to treat employees as "industrial athletes," he said. "You don't see a coach leave (athletes) out on the field for 10 hours with no water."