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Missouri Summer Weather Safety Week |
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| June 18 - 24, 2006 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Two of the biggest weather hazards that affect the United States typically occur during the summer months: Lightning and Excessive Heat. The following table illustrates that pretty well. United States Average Deaths
Table 1. Average number of fatalities per year due to weather phenomena over a 30 year period. The heat figure, 350, covers the period from 1979 to 1995.
Missouri Heat Related Deaths: 1980 - 2005: 852 Missouri Heat Related Deaths 1995-2005: 312 Of the 25 deaths in 2005, 12 were age 65 or older * Source: Missouri Department of Health and Senior Services (DHSS). For additional statistics and information visit the DHSS on the World Wide Web: http://www.dhss.mo.gov
Missouri Lightning Deaths
The above covers reports received by the National Weather Service in The National Weather Service, the Missouri Department of Health and the State Emergency Management Agency have joined together to promote Missouri Summer Safety Week. The following pages include important safety information that can save peoples lives. Please help spread the word about Lightning and Heat Safety so we can have a safe summer. At any given moment, there are 1,800 thunderstorms in progress somewhere on Earth. This amounts to 16 million storms a year! In the United States, there are an estimated 25 million cloud-to-ground lightning flashes each year. While lightning can be fascinating to watch, it is also extremely dangerous. Underrated Problem According to statistics kept by the National Weather Service, the 30 year average for lightning fatalities across the country is 73. Lightning usually claims only one or two victims at a time, and because lightning does not cause mass destruction, such as from a tornado event or a hurricane, lightning generally receives much less attention than the more destructive storm-related events. Due to under reporting, it is estimated that, more realistically, about 100 - 120 deaths per year occur because of lightning. Documented lightning injuries in the United States average 300 per year; however undocumented lightning injuries are likely much higher. In Missouri there have been 86 deaths attributed to lightning from 1959 - 2002, an average of 2 deaths per year. This is right behind the average of 3 deaths per year caused by tornadoes. Missouri ranks 17th nationally in lightning deaths per state. In 2002, there were 5 people killed by lightning in Missouri. Four people died in one event in Willard, in Greene County. The people had taken shelter under a tree during a thunderstorm that was struck by lightning. Another man died in Fenton, in
Lighting has been seen in volcanic eruptions, extremely intense forest fires, surface nuclear detonations, heavy snowstorms, and in large hurricanes. However it is most often seen in individual thunderstorms. We know the cloud conditions necessary to produce lightning, but cannot forecast the location or time of the next stroke of lightning from a storm. Ice is critical to the Lightning Process The formation of ice in a cloud appears to be a very important element in the development of lightning in a storm. The collision of ice and water particles causes separation of the positive and negative electric charges in the particles. Positive charged ice particles tend to collect in the upper parts of the storm, with negative charged particles in the middle and lower parts of the storm. These opposite charges attract, thus "in-cloud" lightning is often produced. Lightning to the Ground As the negative particles gather at the bottom of the storm cloud, a pool of positively charged particles gather along the ground and travel with the storm. As the differences in charges increase, positively charged particles rise up taller objects such as trees, houses, and even people. If you are near a storm, and your hair stands on end, the particles are moving up you! The negative charged particles extend down from the cloud in "steps" and form a step leader. When it gets close enough to the ground or a tall object filled with positive particles, a channel is formed and an electrical transfer takes place. There can be several "strokes" which you see as flickering light. The channel heats to about 30,000 degrees Fahrenheit!. The rapid expansion of the heated air around the channel breaks the sound barrier, and you hear thunder. One lightning stoke can generate between 100 million and 1 billion volts of electricity! Lightning Safety Awareness - An Educational Problem While many people think they are aware of the dangers of lightning, the vast majority are not. Lightning can strike as much as 10 miles away from the rain area of a thunderstorm; that's about the distance that you are able to hear the thunder from the storm. While virtually all people take some protective actions during the most dangerous part of thunderstorms, many leave themselves vulnerable to being struck by lightning as thunderstorms approach, depart, or are nearby. Although some victims are struck directly by the lightning discharge, many victims are struck as the current moves in and along the ground. Where are people when lightning incidents occur? The chart below gives a breakdown.
Gender of Victims: 84% Male, 16% Female Months of Most Incidents: July 30%, August 22%, June 21%
Missouri ranks 17th in deaths. Missouri ranks 31st in injuries. Lightning Safety Outdoors * Remember, lightning can strike up to 10 miles from the rain area. Go quickly inside a completely enclosed building before the storm arrives. Do not go to a carport, open garage, covered patio or open window. A hard topped all metal vehicle also provide good protection * If no shelter is available, do not take shelter under a tree. Avoid being the tallest object in the area. If only isolated trees are nearby, crouch down on the balls of your feet in the open, keeping twice as far away from a tree as it is tall. * Get out of the water, off the beach, and out of small boats or canoes. Avoid standing in puddles of water even if wearing rubber boots. * Do not use metal objects such as golf clubs, metal bats, fishing rods, or metal tools. * Stop tractor work and heavy construction equipment, especially when pulling metal equipment. Indoors * Stay there! The best protection from lightning is a house or other substantial building. However, stay away from windows, doors, and metal pipes. * Do not use electric appliances during the storm. Turn off sensitive equipment such as televisions, VCR's, and computers. * Telephone use is the leading cause of indoor lightning injuries in the United States. Do not make a call unless it is an emergency. Excessive Heat: Another Underrated Problem Many people do not realize how deadly a heat wave can be. In contrast to the visible, destructive, and violent nature of floods, hurricanes, and tornadoes, a heat wave is a "silent killer". In 1995 alone, 1021 Americans perished in heat waves, including 633 in Illinois and 57 in Missouri. The Centers for Disease Control and Prevention (CDC) reports that an average of 350 people perish each year due to the effects of heat. From 1979 - 1999, CDC reported 8015 deaths in the United States from excessive heat exposure. What is a Heat Wave? A heat wave is a period of excessive heat lasting two days or more that leads to illnesses and other stresses on people with prolonged exposure to these conditions. High humidity, which often accompanies heat in Missouri, can make the effects of heat even more harmful. While heat related illness and death can occur due to exposure to intense heat in just one afternoon, heat stress on the body has a cumulative effect. Consequently, persistence of a heat wave increases the threat to public health. The Urban Heat Problem Most heat-related deaths occur in cities. Brick and mortar buildings, asphalt streets, and tar roofs absorb daytime heat and slowly release it at night. Consequently, temperatures in urban areas can be warmer than rural areas by several degrees both day and night. This is commonly called the urban "heat island" effect. In addition to the burden of heat, stagnant conditions often develop during heat waves, with pollutants increasing in concentration near the ground and contributing further to public health problems during heat waves. Socioeconomic factors also place urban residents under extra risk. Some people in cities do not have air conditioning, while people in high crime areas may be afraid to open their windows or venture out to cooler public buildings. Who Is Most Vulnerable During a Heat Wave? The elderly population segment is the most vulnerable to the dangers of heat. Of the 522 deaths that occurred in Chicago during the July 12-16, 1995 heat wave, 371 (73 percent) were age 65 or older. The elderly suffer due to the diminished ability to perspire. Since the function of perspiration is to provide evaporation, which in turn provides cooling, the elderly have a reduced capacity to release heat from the body. In addition to the elderly, infants, young children, and people with chronic health problems (especially pre-existing heart disease) or disabilities are more vulnerable to the effects of heat waves. People who are not acclimated to hot weather, overexert themselves, are obese, or use alcohol or drugs (including drugs such as antipsychotics, tranquilizers, antidepressants, certain types of sleeping pills, and drugs for Parkinson's disease) are at great risk. (Source- Centers for Disease Control and Prevention-Morbidity and Mortality Weekly Report) Measuring the Combined Effects of Heat and Humidity The National Weather Service uses the Heat Index (HI) to compute the "apparent temperature," which is a measure of how hot it feels to people at a certain combination of temperature and humidity. The heat index values used in forecasts, advisories, and warnings assume an average size adult, with light clothing, in the shade, with a 5 mile per hour wind. Being in full sun, or in an area with little air movement, can increase the apparent temperature, and thus increase the risk for adverse effects from the heat and humidity. Winds greater than 5 miles per hour usually enhance evaporative cooling and decrease the apparent temperature and the health threat from the heat. As noted, the impacts of heat are cumulative over time. The greatest number of heat-induced illnesses and fatalities usually peak two days after the maximum heat index values occurred. The National Weather Service in St. Louis will issue Heat Advisories when a HI of 105 F will be reached for at least 3 hours. A Heat Warning will be issued if the HI will reach 105 for at least 3 days or more, or if the HI will reach 115 F on a day. Heat Index The Heat Index (Apparent Temperature) can be found by taking the temperature (number on the left) and relative humidity value (number at the top) and matching them on this table. For example, a temperature of 90 degrees Fahrenheit and a relative humidity of 45 percent gives you a heat index of 93 degrees.
Download the HEAT INDEX CARD in pdf format
Table 2: A list of common heat-induced health problems and their suggested treatment (Reference: The American Red Cross)
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- Page last modified: 9-Jun-2006 3:57 PM UTC
