Sweltering in Seattle?

General Article

Tips from EH&S to help you anticipate and survive extreme summer heat in the city

These are the "dog days of summer" — 20 days before and 20 days after the period in July when the dog star, Sirus, is in conjunction with the sun. The ancients living around the Mediterranean believed Sirius' heat added to the heat of the sun, creating a stretch of hot and sultry weather. With summer weather moderated by our proximity to the Pacific Ocean, stretches of extreme heat in our region are rare. So when periods the National Weather Service (NWS) calls "excessive-heat events" hit, are you prepared? Environmental Health and Safety has some heat history and suggestions that may help.

Public-health impact

Extreme heat has a disproportionate public-health impact in cities. Roads and buildings absorb the sun's energy and contribute to the formation of "heat islands." While rural areas cool off at night, cities retain this absorbed heat. By comparison, urban residents get less nighttime relief.

Heat waves do not evoke the same sense of widespread urgency or fear as hurricanes, floods, tornadoes and earthquakes. Although they are far less property-destructive, excessive heat has claimed more lives over the past 15 years than all other extreme weather events combined.

During an average summer, approximately 1,500 people in the United States die from extreme heat. A single heat wave in Chicago killed more than 700 people in 1995. In Europe, a record heat wave claimed an estimated 35,000 lives in 2003. In both cases, most of the victims were 65 or older. Statistics show that just in the Seattle area alone, the city has averaged four hot weather-related deaths per summer since the mid 1970s, and had as many as 60 deaths during the warm summer of 1992.

Since our summer weather is relatively mild compared to other parts of the country, home air conditioning is quite uncommon. So when it gets unseasonably hot, our bodies struggle to cope with the heat and experience considerable health stress. In addition to the heat of the day, the stress is extended when our homes remain uncomfortably warm at night and it's hard to sleep.

Most heat-related deaths are not direct heat-related illnesses like heat stress or heat stroke, but rather more indirect health issues, such as heart attacks, strokes and respiratory illnesses. The most vulnerable to heat-related illnesses are the elderly and the very young.

For the growing number of aging Americans, the body's cooling mechanisms may become impaired. Living alone or being confined to a bed and unable to care for one's self further increases risk. During an excessive-heat event, the body normally cools itself by increasing blood flow to the skin and perspiring. Heat-related illness and mortality occur when the body's temperature-control system becomes overloaded. When this happens, perspiring may not be enough.

For years, to save lives, the NWS has used a heat- index formula combining high temperatures and humidity. Recognizing people respond to heat differently in different regions of the country, the NWS has developed a heat health watch/warning system that tailors excessive-heat guidance to specific regions in the country. It is designed with custom rules based on the city's climatology. For instance, Seattle's system issues a heat and heath watch if daytime highs are expected to reach the 90s.

The system provides guidance to forecasters in the NWS Seattle office, based on their forecast information and a sophisticated statistical analysis of the heat threat. Forecasters can then issue excessive-heat outlooks, watches, warnings and advisories, depending on the lead time before the event and the intensity of the event. The warning message is transmitted to area media outlets, emergency management and health community officials just like other weather or flood-warning messages. The excessive-heat messages are also posted on the NWS Web site at www.wrh.noaa.gov/sew, aired on NOAA Weather Radio, and many other resources for the public.

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Preparing for extreme heat

• Install air conditioning. If that is not possible, predetermine where you could go to take advantage of air conditioning, like a mall, store, movie house or other air-conditioned building. You can also obtain an appropriate number of fans for your home. They will help circulate air and evaporate sweat, cooling your body.
• Have plenty of water available.
• Have non-protein type foods in stock. Foods like meat increase metabolic heat production and increase water loss.
• If you have an outdoor exercise regime, plan to do your exercising during cooler periods of the day.

What to do when heat hits

• Slow down. Avoid, reduce or reschedule strenuous activities to a cooler period of the day.
• Drink plenty of water, even if not feeling thirsty. Your body needs water to help keep you cool. (Those on fluid restrictions should consult their physician.)
• Dress for summer. Dress in lightweight, light-colored clothing. They help your body maintain more normal temperatures.
• Spend more time in air-conditioned places. If you do not have home air conditioning, spend at least some time in other air-conditioned places like malls or stores. Even a few hours a day in air conditioning can greatly reduce the risk.
• Don't get too much sun. Sunburn makes your body's job of heat dissipation that much more difficult.
• Avoid alcoholic or caffeinated beverages. These beverages dehydrate the body and make the heat's effects worse on your body.
• Do not take salt tablets unless specified by a physician.
• Avoid strenuous outdoor activities, particularly during the heat of the day.
• Visit at-risk individuals at least twice a day. Watch for signs of heat-related illness such as hot, dry skin, confusion, hallucinations and aggression.

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