Preparing for and Responding to Extreme Heat and Cold Events

The Health Studies Branch (HSB) conducts planned research and provides emergency epidemiologic response to assess the acute and chronic health effects from exposure to extreme heat and cold. HSB provides subject matter expertise on heat and cold and addresses concerns and inquires from the CDC, external partners, and the media. HSB epidemiologists have co-authored several studies and publications of heat and cold-related morbidity and mortality such as

• Heat-Related Deaths — United States, 1999–2005
• Heat-related Illness (HRI) among High School Athletes
• Hypothermia Emergency Department Visits — United States, 1995-2004
• Extreme Heat Events Guidebook

HSB provides emergency epidemiologic technical assistance during or immediately after a heat wave or extreme winter weather event as requested. These epidemiologic responses assist state health departments in assessing the magnitude and impact from the extreme weather event. HSB recent responses include the

• Kentucky Ice Storms in 2009
• Arizona Heat Wave of 2005

Review HSB Disaster Response Activities

HSB Preparedness and Research Activities

Provide subject matter expertise

• Provide scientific expertise on heat and cold inquiries from CDC, external partners, and the media (e.g., content for CDC Media Releases for advisories during extreme weather events).
• Update CDC’s heat and cold preparedness websites for the public
• Promote and review CDC preparedness products

Applied epidemiology and research of heat and cold-related morbidity and mortality

• Examine various methodologies for identifying heat and cold-related health outcomes for surveillance
• Evaluate risk factors contributing to cold and heat-associated mortality every several years using data from CDC’s National Center for Health Statistics.
• Collaborate with partners to characterize regional and seasonal aspects of heat and cold-related morbidity and mortality among vulnerable groups (e.g., migrant farmer workers, high school athletes)
• Disseminate our findings through publications and presentations

Technical assistance to states (e.g., Epi-Aids)

• Conduct rapid epidemiologic investigations during extreme weather events on specific health concerns by state or local authorities such as carbon monoxide exposure in homes during power outages and surveillance in temporary evacuee shelters.
• Provide assistance in conducting active surveillance of deaths, hospitalizations, and emergency department visits during an extreme weather event.
• Assist states in conducting a rapid needs assessment in impacted communities during an extreme weather event to characterize general and health needs using CDC’s Community Assessment for Public Health Emergency Response (CASPER) methodology.

MMWR and Publications

Heat Illness among High School Athletes --- United States, 2005-2009.
MMWR 2010;59:1009-13. CDC analyzed data from the National High School Sports-Related Injury Surveillance Study from the 2005–2006 through the 2008–2009 school years to determined the incidence and characteristics of heat illness (HRI) among high school athletes. An estimated 9,000 HRI cases occur every year and more frequently in football and during the hot and humid summer months.

Heat-Related Deaths--United States 1999–2005
During 1999–2005, a total of 3,981 heat-related deaths were reported, resulting in approximately 569 heat-related deaths per year in the United States. Older adults and young children are particularly susceptible to heat-related illnesses and are at high risk for heat-related mortality. Black or African American males had a higher crude rate for heat-related deaths than any other race, across all age groups [Link to figures – see figures 1 and 2 them below].

Heat Related Deaths--United States 1999-2003
MMWR 2006 / 55(29);796-798 [Link to article here and below on list] Analysis of 1999-2003 National Center for Health Statistics (NCHS) mortality records with underlying cause of death was recorded as exposure to excessive natural heat. CDC found that risk factors for heat-related deaths were being male gender, >65 years old, and warm climates. Arizona (1.7 deaths per 100,000) and Nevada (0.8 deaths per 100,000) had the highest heat-related death rates.

Hypothermia-Related Deaths --- United States, 2003--2004
MMWR 2005;54(07):173-175. During 1979–2002, a total of 16,555 deaths in the U.S., an average of 689 per year (range: 417–1,021), were attributed to “exposure to excessive natural cold.” Annual death rates were highest before 1990 (range 0.3–0.4 per 100,000 population), then decreased to 0.2 beginning in 1991, except for an increase to 0.3 in 2000.

Hypothermia and other cold-related morbidity emergency department visits: United States, 1995-2004.
Wilderness and Environmental Medicine 2008;19:233-237. [Link to article here and below on list] CDC identified hypothermia and other cold-related morbidity emergency department (ED) visits from the 1995-2004 National Ambulatory Medical Care Surveys. The study determined an estimated 15,574 (95% CI = 9,103-22,045) hypothermia visits during the study period. Compared with other ED patients, those with hypothermia diagnoses were older (mean age 45 vs. 36 years: p=.009) and were more likely to be uninsured (Risk Ratio [RR] = 2.44; 95% CI= 1.54-3.84). In addition, these hypothermia-related ED visits required more transfers to critical care units (RR = 6.73; CI 1.8-25.0) than did other ED visits. Hypothermia morbidity is a preventable resource intensive condition.

Additional Cold related publications

Additional Heat related publications