Washington, July 11 : A study conducted in the Southeastern United States has shown a link between thunderstorms and asthma attacks in the metro Atlanta area that could have a 'significant public health impact.'
Although a relationship between thunderstorms and increased hospital visits for asthma attacks has been known and studied worldwide for years, this is the first time a detailed study of the phenomenon has been conducted in the American South.
For the study, researchers at the University of Georgia and Emory University examined a database consisting of more than 10 million emergency room visits in some 41 hospitals in a 20-county area in and around Atlanta for the period between 1993 and 2004.
They found a three percent higher incidence of visits for asthma attacks on days following thunderstorms.
"While a three percent increase in risk may seem modest, asthma is quite prevalent in Atlanta, and a modest relative increase could have a significant public health impact for a region with more than five million people," said Andrew Grundstein, a climatologist in the department of geography at UGA and lead author on the research.
Grundstein went on to say that 'three percent is likely conservative because of limitations in this study.'
Researchers said that the most prominent hypothesis as to why it happens is that 'pollen grains may rupture upon contact with rainwater, releasing respirable allergens, and that gusty winds from thunderstorm downdrafts spread particles . . . which may ultimately increase the risk of asthma attacks.'
The team used thunderstorm occurrences from meteorological data gathered at Atlanta's Hartsfield-Jackson International Airport and compared that information with the vast database of emergency room visits to arrive at the figure of a three percent increase in asthma-related emergency room visits following thunderstorms for the study period.
In all, during the 11-year period, there were 564 thunderstorm days, and in order to better understand the physical mechanisms that relate thunderstorms and asthma, researchers also mined the information on total daily rainfall and maximum five-second wind gusts, which they used as 'a surrogate for thunderstorm downdrafts and to indicate the maximum wind speed of the storm.'
In all, there were 215,832 asthma emergency room visits during the period and 28,350 of these occurred on days following thunderstorms.
Grundstein said that while the new study is the first of its kind in the South and does clearly indicate a relationship between thunderstorms and asthma in the metro Atlanta area, much more work remains.
"Obtaining a better understanding of the mechanistic basis of the phenomenon of thunderstorm-induced asthma will allow for better intervention strategies and improved emergencies services planning. This will be particularly important in the era of climate change," said Stefanie Ebelt Sarnat of Emory.
The study was published in the online edition of the medical journal Thorax.