How Many Hospital admissions in Massachusetts Would Have Been Saved, Had the Particulate Air Pollution Level Been Lower?

Abstract

TPS 681: Short-term health effects of air pollutants 1, Exhibition Hall, Ground floor, August 26, 2019, 3:00 PM - 4:30 PM Background: Numerous studies have found higher cardiorespiratory risk associated with particulate matter smaller than 2.5µm in diameter (PM2.5). Most studies have used classical epidemiological methods, limited in their capacity for causal interpretation. We applied a causal modeling approach to assess the short-term impact of high PM2.5 exposure on hospital admissions in Massachusetts. Methods: Daily ZIPcode counts of respiratory and cardiovascular admissions of Medicare beneficiaries >65 were constructed across Massachusetts (2000 -2014). Daily PM2.5 exposure estimates were obtained from a satellite-based spatio-temporally resolved model. A propensity score matching approach was applied to estimate the number of cause-specific hospital admissions attributed to high levels of two-day average exposure to PM2.5 (exposure ≥the 95th percentile=18 µg/m3). Each high pollution ZIP code-day was matched to a low pollution ZIP code-day with similar background characteristics. Then, the impact of PM2.5 exposure was estimated by comparing the total count of admissions (all respiratory, all CVD, myocardial infarction (MI), Ischemic heart disease (IHD), ischemic stroke, congestive heart disease (CHF), and chronic obstructive pulmonary disease (COPD)) on high pollution ZIPcode-days and matched low pollution ZIPcode-days during the study period. Results: Of the days in the study period 187,184 were high-pollution days. The mean and standard deviation of the PM2.5 exposure was 11.4 ± 3.7 µg/m3 in the low pollution days and 22.1 ± 4.5 µg/m3 in the high pollution days. A total of 1,729 (7.1%) respiratory, 618 (1.7%) CVD, 362 (6.4%) COPD, 127 (1.9%) stroke, 119 (1.9%) MI, 122 (0.9%) IHD, and 420 (3.7%) CHF admissions in high pollution days were attributed to PM2.5 exposure. Conclusion: Had there been an intervention to lower the short-term exposure limit to PM2.5 below 18µg/m3, well below the current 24-hours 35 µg/m3 U.S.EPA threshold, a significant number of hospital admissions would have been saved among the study population within the study period.