Long-Term PM2.5 Exposure and Risks of Ischemic Heart Disease and Stroke Events: Review and Meta-Analysis

Abstract

Background Fine particulate matter <2.5 µm in diameter (PM_2.5) has known effects on cardiovascular morbidity and mortality. However, no study has quantified and compared the risks of incident myocardial infarction, incident stroke, ischemic heart disease (IHD) mortality, and cerebrovascular mortality in relation to long-term PM_2.5 exposure. Methods and Results We sought to quantitatively summarize studies of long-term PM_2.5 exposure and risk of IHD and stroke events by conducting a review and meta-analysis of studies published by December 31, 2019. The main outcomes were myocardial infarction, stroke, IHD mortality, and cerebrovascular mortality. Random effects meta-analyses were used to estimate the combined risk of each outcome among studies. We reviewed 69 studies and included 42 studies in the meta-analyses. In meta-analyses, we found that a 10-µg/m³ increase in long-term PM_2.5 exposure was associated with an increased risk of 23% for IHD mortality (95% CI, 15%-31%), 24% for cerebrovascular mortality (95% CI, 13%-36%), 13% for incident stroke (95% CI, 11%-15%), and 8% for incident myocardial infarction (95% CI, -1% to 18%). There were an insufficient number of studies of recurrent stroke and recurrent myocardial infarction to conduct meta-analyses. Conclusions Long-term PM_2.5 exposure is associated with increased risks of IHD mortality, cerebrovascular mortality, and incident stroke. The relationship with incident myocardial infarction is suggestive of increased risk but not conclusive. More research is needed to understand the relationship with recurrent events.

Keywords: air pollution; cardiovascular; long‐term; mortality; particulate matter.

Figure 1. Meta‐analysis of the relative risk of ischemic heart disease mortality per 10‐µg/m³ increase in long‐term fine particulate matter <2.5 µm in diameter exposure, combining the effects of 23 studies. ¹¹

AHS indicates Agricultural Health Study; AHSMOG, Adventist Health Study on the Health Effects of Smog; CanCHEC, Canadian Census Health and Environment Cohort; CNBSS, Canadian National Breast Screening Study; CPRD, Clinical Practice Research Datalink; CPS‐II, American Cancer Society Cancer Prevention Study‐II; EFFECT, Enhanced Feedback For Effective Cardiac Treatment; ESCAPE, European Study of Cohorts for Air Pollution Effects; HR, hazard ratio; NHIS, National Health Interview Survey; NIH‐AARP, National Institutes of Health—AARP Diet and Health Study; REGARDS, Reasons for Geographic and Racial Differences in Stroke; RoLS, Rome Longitudinal Study; and WHI, Women's Health Initiative.

Figure 2. Meta‐analysis of the relative risk of incident acute myocardial infarction per 10‐µg/m³ increase in long‐term fine particulate matter <2.5 µm in diameter exposure, combining the effects of 11 studies. ¹²

CPRD indicates Clinical Practice Research Datalink; ESCAPE, European Study of Cohorts for Air Pollution Effects; HR, hazard ratio; ONPHEC, Ontario Population Health and Environment Cohort; REGARDS, Reasons for Geographic and Racial Differences in Stroke; and WHI, Women's Health Initiative.

Figure 3. Meta‐analysis of the relative risk of cerebrovascular mortality per 10‐µg/m³ increase in long‐term fine particulate matter <2.5 µm in diameter exposure, combining the effects of 17 studies. ¹³

AHS indicates Agricultural Health Study; CanCHEC, Canadian Census Health and Environment Cohort; CNBSS, Canadian National Breast Screening Study; CPRD, Clinical Practice Research Datalink; CPS‐II, American Cancer Society Cancer Prevention Study‐II; ESCAPE, European Study of Cohorts for Air Pollution Effects; HR, hazard ratio; HIMS, Health in Men Study; NHIS, National Health Interview Survey; NIH‐AARP, National Institutes of Health—AARP Diet and Health Study; and WHI, Women's Health Initiative.

Figure 4. Meta‐analysis of the relative risk of incident stroke per 10‐µg/m³ increase in long‐term fine particulate matter <2.5 µm in diameter exposure, combining effects of 14 studies. ¹¹

China‐PAR indicates Prediction for Atherosclerotic Cardiovascular Disease Risk in China; CPRD, Clinical Practice Research Datalink; ESCAPE, European Study of Cohorts for Air Pollution Effects; HR, hazard ratio; HIMS, Health in Men Study; ONPHEC, Ontario Population Health and Environment Cohort; and WHI, Women's Health Initiative.