A systematic review of air pollution and incidence of out-of-hospital cardiac arrest

Introduction Studies have linked air pollution with the incidence of acute coronary artery events and cardiovascular mortality but the association with out-of-hospital cardiac arrest (OHCA) is less clear. Aim To examine the association of air pollution with the occurrence of OHCA. Methods Electronic bibliographic databases (until February 2013) were searched. Search terms included common air pollutants and OHCA. Studies of patients with implantable cardioverter defibrillators and OHCA not attended by paramedics were excluded. Two independent reviewers (THKT and TAW) identified potential studies. Methodological quality was assessed by the Newcastle-Ottawa Scale. Results Of 849 studies, 8 met the selection criteria. Significant associations between particulate matter (PM) exposure (especially PM2.5) and OHCA were found in 5 studies. An increase of OHCA risk ranged from 2.4% to 7% per interquartile increase in average PM exposure on the same day and up to 4days prior to the event. A large study found ozone increased the risk of OHCA within 3h prior to the event. The strongest risk OR of 3.8-4.6% per 20 parts per billion ozone increase of the average level was within 2h prior to the event. Similarly, another study found an increased risk of 18% within 2days prior to the event. Conclusions Larger studies have suggested an increased risk of OHCA with air pollution exposure from PM2.5 and ozone.