Triggering of ST-elevation myocardial infarction by ultrafine particles in New York: changes following Tier 3 vehicle introduction

Abstract

BACKGROUND AND AIM: Previously, we found increased rates of ST-elevation myocardial infarction (STEMI) associated with increased ultrafine particle (UFP; <100nm) concentrations in the previous few hours in Rochester, New York. Rates were higher after air quality policies and a recession reduced pollutant concentrations (2014-2016 versus 2005-2013), suggesting PM composition had become more toxic. Tier 3 light duty vehicles, which should produce less primary organic aerosols and oxidizable gaseous compounds, likely making PM less toxic, were introduced in 2017. Because of this, we hypothesized we would observe a lower relative STEMI rate in 2017-2019 than 2014-2016. METHODS: Using STEMI events treated at the University of Rochester Medical Center (2014-2019), local UFP and other pollutant concentrations, a case-crossover design, and conditional logistic regression models, we separately estimated the rate of STEMI associated with increased UFP and other pollutants in the previous hours and days in the 2014-2016 and 2017-2019 periods. RESULTS: An increased rate of STEMI was associated with each 3121 particles/cm3 increase in UFP concentration in 2014-2016 (lag hour 0: OR=1.23; 95% CI = 1.08, 1.41), but not in 2017-2019 (OR=0.93; 95% CI = 0.79, 1.09). There were similar patterns for black carbon, UFP11-50nm, and UFP51-100nm. In contrast, increased rates of STEMI were associated with 0.6ppb increases in SO2 concentrations in the previous 120 hours in both periods (2014-2016: OR=1.25, 95% CI = 1.00, 1.36; 2017-2019: OR=1.22, 95% CI = 0.88, 1.68). CONCLUSIONS: Greater rates of STEMI were associated with short term increases in concentrations of UFP and other motor vehicle related pollutants before Tier 3 introduction (2014-2016), but not afterwards (2017-2019). This change may be due to changes in PM composition, to increased exposure misclassification and greater underestimation of effects from 2017-2019, and/or changes in therapeutic approaches such as preventive aspirin use. KEYWORDS: myocardial infarction, air pollution, ultrafine particles, case-crossover