Outdoor air pollution as a trigger for out-of-hospital cardiac arrests.
BACKGROUND
Epidemiologic studies have reported associations between fine particulate air pollution and cardiovascular mortality or hospitalization for cardiac events. However the evidence regarding the association between air pollution and acute cardiac events, such as out-of-hospital cardiac arrest, is inconsistent.


METHODS
We investigated the association between particulate matter (PM) air pollution and out-of-hospital cardiac arrest using a case-crossover study of adults (age, 35+ years) in Melbourne, Australia. We included 8434 cases identified through the Victorian Cardiac Arrest Registry from 2003 through 2006. We excluded arrests with an obvious preceding noncardiac event such as trauma, poisoning, or drowning, leaving only those events that were presumed to have cardiac etiology. Air pollution concentrations obtained from a central monitoring site were used for day of the arrest and for lag 1, lag 2, and lag 3, including the average lag 0-1.


RESULTS
An interquartile range increase of 4.26 microg/m3 in PM2.5 over 2 days (lag 0-1) was associated with an increase in risk for an out-of-hospital cardiac arrest of 3.6% (95% confidence interval = 1.3% to 6.0%). PM10 and carbon monoxide also showed associations, but not as strong as for PM2.5. Longer lag periods did not show such strong relationships. There was no association of these cardiac events with ozone, sulfur dioxide, or nitrogen dioxide in any lag period. Individuals age 65-74 years old were most susceptible to PM2.5 exposure, while those 75 years and older had the lowest risk.


CONCLUSIONS
These findings support an association between daily average PM2.5 concentrations and an increased risk of out-of-hospital cardiac arrests.
Dennekamp
Martine
M
Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, Victoria, Australia. martine.dennekamp@med.monash.edu.au
Akram
Muhammad
M
Abramson
Michael John
MJ
Tonkin
Andrew
A
Sim
Malcolm Ross
MR
Fridman
Masha
M
Erbas
Bircan
B
D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000397:Air Pollution / Q000009:adverse effects* / Q000032:analysis / Q000706:statistics & numerical data; D002248:Carbon Monoxide / Q000009:adverse effects; D016001:Confidence Intervals; D005260:Female; D006323:Heart Arrest / Q000453:epidemiology / Q000209:etiology*; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009585:Nitrogen Dioxide / Q000009:adverse effects; D010126:Ozone / Q000009:adverse effects; D052638:Particulate Matter / Q000009:adverse effects* / Q000032:analysis; D016012:Poisson Distribution; D016016:Proportional Hazards Models; D012042:Registries; D012307:Risk Factors; D012737:Sex Factors; D013458:Sulfur Dioxide / Q000009:adverse effects; D014739:Victoria / Q000453:epidemiology
D052638:Particulate Matter; D013458:Sulfur Dioxide; D010126:Ozone; D002248:Carbon Monoxide; D009585:Nitrogen Dioxide