Wildfire smoke linked to HF risk
MedWire News: Smoke from wildfire fueled by peat leads to an increase in emergency room (ER) visits for heart failure (HF) and respiratory events, a US Environmental Protection Agency (EPA) study has found.
In June 2008, a lightning strike in eastern North Carolina caused a wildfire in which burning deposits of peat produced haze and air pollution in excess of US National Ambient Air Quality Standards.
Ana Rappold (EPA, Research Triangle Park, North Carolina) and colleagues conducted a population-based study using ER visits reported through the North Carolina Disease Event Tracking and Epidemiologic Collection Tool (NCDETECT) syndromic surveillance program to ascertain the effects of the wildfire smoke on cardiorespiratory outcomes in the affected population.
They determined a smoke exposure window which ranged from June 1st 2008, when the wildfire started, to July 14th 2008, when it was contained. June 10-12th during this window was classified as a high exposure period. The researchers then estimated risks associated with the high-exposure days and a 1-5 day lag period following each exposure day, relative to the non-exposed days of the study period.
Rappold's team ascertained the counties most affected by the smoke using aerosol optical depth measured by a satellite.
Regression analysis was used to estimate changes in the cumulative relative risk (RR) of cardiac outcomes including HF, myocardial infarction (MI), and cardiac dysrhythmias over the study period. Counties were classified as exposed if they had been exposed to smoke for at least 2 days (n=18).
The findings showed that in the exposed counties, the cumulative RR for HF-related ER visits during the high exposure and lag days was increased 1.37-fold compared with non-exposed days, whereas there was no difference between these periods in the reference counties. ER visits for MI and cardiac dysrhythmias were not increased during the same time periods, however.
In the exposed counties, ER visits for respiratory outcomes including asthma,chronic obstructive pulmonary disease, pneumonia and acute bronchitis were also elevated 1.66-fold during these periods, whereas they were not increased in the referent counties.
"The consistent increase in RR in the exposed counties for nearly all outcome categories during and up to 5 days after exposure to wildfire smoke is striking and persuasive, and has potentially significant public health implications," conclude the authors.
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By Piriya Mahendra