"Historically, we know that episodes of extremely hot or cold temperatures increase mortality. Global warming and other weather phenomena, such as El Nino, have warranted the need for further investigation into the weather-mortality relation," says lead author Frank Curriero, PhD, an assistant scientist in the Department of Biostatistics at the Johns Hopkins Bloomberg School of Public Health. "We explored this relation in cities along the eastern United States, to further characterize the effects of temperature as varied by latitudes as well as other factors particular to a specific city or area."
The researchers chose 11 large metropolitan areas in the eastern United States and compared daily weather and mortality data for 1973 to 1994. The analyses was performed in two stages. First, the relationship between temperature and mortality risk from cardio-vascular, respiratory, and other diseases was estimated for each city; then the variation in risk across cities, due to difference in latitude and other variables, was examined.
Within the selected cities, mortality risk decreased as temperature increased from the coldest days; however, after a certain critical temperature threshold, referred to as the minimum mortality temperature, mortality risk increased in most of the cities as temperature increased. The minimum mortality temperature threshold ranged between approximately 65 and 70 degrees Fahrenheit for cities in the North (Boston, Chicago, New York City, Philadelphia, Baltimore, and Washington, DC) and approximately
Contact: Ming Tai or Tim Parsons
Johns Hopkins University Bloomberg School of Public Health