The impact of short-term exposure to air pollutants on the onset of out-of-hospital cardiac arrest: A systematic review and meta-analysis

Abstract

Background: Acute exposure to outdoor air pollution was considered to be associated with the incidence of out-of-hospital cardiac arrest (OHCA). But the relation between specific air pollutants and OHCA remains controversial. We conducted a systematic review and meta-analysis to quantitatively assess the acute effects of air pollutants, including particulate matter (PM₁₀ and PM_2.5), sulfur dioxide (SO₂), nitrogen dioxide (NO₂), carbon monoxide (CO) and ozone (O₃) on OHCA onset.

Methods: Six databases were searched to identify studies analyzing the association between OHCA and the main air pollutants. We summarized the pooled estimates using random-effect models. Heterogeneity within studies was assessed using Cochran's Q and I² statistics. Funnel plots, Egger's regression test and Begg's rank correlation method were constructed to evaluate publication bias. Subgroup analyses and sensitivity analyses were also conducted to evaluate the potential sources of heterogeneity.

Results: A total of 15 studies met the inclusion criteria. PM₁₀, PM_2.5, NO₂ and O₃ were found to be significantly associated with increase in OHCA risk (PM₁₀ 1.021, 95%CI: 1.006-1.037; PM_2.5 1.041, 95%CI: 1.012-1.071; NO₂ 1.015, 95%CI: 1.001-1.030 and O₃ 1.016, 95%CI: 1.008-1.024). The acute exposure to SO₂ and CO was not associated with the incidence of OHCA. Additional analyses verified the findings in the overall analyses except SO₂ and NO₂. Population attributable fractions for PM₁₀, PM_2.5, and O₃ were 2.1%, 3.9% and 1.6%, respectively.

Conclusion: The current evidence confirmed the associations between short-term exposure to PM_2.5, PM₁₀ and O₃ and a high risk of OHCA, with the strongest association being observed for PM_2.5.

Keywords: Air pollutant; Meta-analysis; Out-of-hospital cardiac arrests.