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Skip Navigation LinksDNREC : Climate Change : Climate Change Delaware's public health

Climate Change


 Delaware's public health


While it's easy to picture how sea level rise could devastate coastal property and wetlands, visualizing climate change impacts on human health might be more difficult at first. Difficult or not, however, these impacts are very real. Public health impacts from climate change in Delaware could include increased mortality from summer heat waves, increased incidents of asthma and other severe respiratory conditions, and increased potential for the transmission of vector- and water-borne infectious diseases.


Heat Waves


Heat waves are extremely dangerous to human health, and heat is often a direct cause of weather-related human death. For example, the 2003 European heat wave killed at least 21,000 people across five different countries (Epstein, 2005). The 1995 heat wave in Chicago caused an estimated 750 deaths (Semenza et al., 1996). According to the Centers for Disease Control and Prevention, heat ranks among the top weather-related killers in the United States. Between 1999 and 2003, heat waves killed over 3,440 people—more than hurricanes, tornadoes, lighting and floods combined. This estimate is conservative, as many heat-related deaths in the U.S. are probably underreported.


The most recent Intergovernmental Panel on Climate Change (IPCC) report indicates that hot days, hot nights, and extreme heat waves are projected to increase over the coming years. The Northeast Climate Impacts Assessment (NCIA) also projects a dramatic increase in extremely hot days over the coming century for Northeast states, increasing the risk of heat-related illness (heat stress, heat exhaustion) and death from heat stroke, especially among  vulnerable populations. For example, while Philadelphia has historically experienced on average two days per summer over 100 oF, the NCIA estimates this will increase to around 28 days by the end of the century.

If continued global warming increases the intensity, extent, and duration of heat waves, summer heat-related mortality is certain to rise. Photo: NASA


A new study by Kalkstein and Greene (2007) estimates that global warming will contribute to 162 additional deaths per year in the Philadelphia metropolitan area by mid-century. These estimates are quite disconcerting given Delaware’s close proximity. In fact, the Environmental Protection Agency (EPA) has estimated that the average temperature in Dover, Del., has increased by 1.7 oF over the last century. Given the high probability of continued climate change over the next century, even in Delaware, it is likely that Delaware citizens’ health will be at risk from increased heat waves, especially in urban areas.

Ground-level ozone is one of the major contributors to city smog, as seen in the picture above. According to the EPA, Delaware’s ground-level ozone concentrations exceed national standards throughout the state.


Air Quality


High temperatures and humidity levels increase the harmful effects of poor air quality, which already puts large numbers of people in the Northeast at risk from asthma, chronic bronchitis, and emphysema (NCIA).

According to Epstein (2005), the prevalence of asthma in the U.S. has quadrupled over the past two decades in part because of increased pollution levels, increased pollen and dust particles, and other climate-related factors. Air pollution from ground-level ozone also is a major concern for the Northeast, and increased temperatures from global warming could increase concentrations of ground-level ozone in the region. Moreover, if warmer climate causes increased use of air conditioners, air pollutants like NOx and SOx from power plants also will rise.

Human health risks from poor air quality are a major concern in Delaware. According to the EPA, ground-level ozone concentrations exceed national standards throughout the state,

with Wilmington and the northern part of Delaware classified as “severe” nonattainment areas for ozone. Ozone reduces lung function, aggravates asthma, and induces respiratory inflammation. According to the NCIA, the Philadelphia-Camden-Vineland area, which includes Delaware’s New Castle County, ranks 10th among the nation’s 25 most ozone-polluted metropolitan areas. Thus, warmer temperatures from climate change will continue to put Delaware citizens’ health at risk.


Infectious Disease


Warmer temperatures across the United States are projected to extend the habitat and range of microbes and the insects that carry infectious disease. Although vector-borne diseases cause comparatively few deaths, warmer temperatures and increased precipitation events could increase the public health risk in Delaware.

For example, mosquitoes flourish in parts of Delaware, and can carry malaria, equine encephalitis, or West Nile Virus. Research shows that warm summer conditions, especially in conjunction with heavy rain events, stimulate mosquito breeding and biting. Lyme disease already occurs in Delaware, and Deer Tick populations that carry the disease could increase as global warming causes temperatures to rise. Warmer surface waters also could contribute to increased intensity and duration of harmful algal blooms, which can harm aquatic habitat, damage shellfish nurseries and can be toxic to humans.

Without control efforts, mosquitos breed almost anywhere permanent or temporary standing water is found. A DNREC Mosquito Control Section technician sprays insecticides above to help thwart mosquito reproduction.

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