The association between short and long-term exposure to PM 2.5 and temperature and hospital admissions in New England and the synergistic effect of the short-term exposures

Abstract

<div class="section"> <a class="named-anchor" id="S1"> <!-- named anchor --> </a> <h5 class="section-title" id="d320161e149">Background</h5> <p id="P1">Particulate matter&lt;2.5μm in diameter (PM _2.5) and heat are strong predictors of morbidity, yet few studies have examined the effects of long-term exposures on non-fatal events, or assessed the short and long-term effect on health simultaneously. </p> </div><div class="section"> <a class="named-anchor" id="S2"> <!-- named anchor --> </a> <h5 class="section-title" id="d320161e157">Objective</h5> <p id="P2">We jointly investigated the association of short and long-term exposures to PM _2.5 and temperature with hospital admissions, and explored the modification of the associations with the short-term exposures by one another and by temperature variability. </p> </div><div class="section"> <a class="named-anchor" id="S3"> <!-- named anchor --> </a> <h5 class="section-title" id="d320161e165">Methods</h5> <p id="P3">Daily ZIP code counts of respiratory, cardiac and stroke admissions of adults ≥65 (N=2,015,660) were constructed across New-England (2001-2011). Daily PM _2.5 and temperature exposure estimates were obtained from satellite-based spatio-temporally resolved models. For each admission cause, a Poisson regression was fit on short and long-term exposures, with a random intercept for ZIP code. Modifications of the short-term effects were tested by adding interaction terms with temperature, PM _2.5 and temperature variability. </p> </div><div class="section"> <a class="named-anchor" id="S4"> <!-- named anchor --> </a> <h5 class="section-title" id="d320161e176">Results</h5> <p id="P4">Associations between short and long-term exposures were observed for all of the outcomes, with stronger effects of long-term exposures to PM _2.5. For respiratory admissions, the short-term PM _2.5 effect (percent increase per IQR) was larger on warmer days (1.12% versus −0.53%) and in months of higher temperature variability (1.63% versus −0.45%). The short-term temperature effect was higher in months of higher temperature variability as well. For cardiac admissions, the PM _2.5 effect was larger on colder days (0.56% versus −0.30%) and in months of higher temperature variability (0.99% versus −0.56%). </p> </div><div class="section"> <a class="named-anchor" id="S5"> <!-- named anchor --> </a> <h5 class="section-title" id="d320161e190">Conclusions</h5> <p id="P5">We observed synergistic effects of short-term exposures to PM _2.5, temperature and temperature variability. Long-term exposures to PM _2.5 were associated with larger effects compared to short-term exposures. </p> </div><p id="P6"> <div class="figure-container so-text-align-c"> <img alt="" class="figure" src="/document_file/4a569032-69e1-45d4-88ef-e1d24e327c71/PubMedCentral/image/nihms971481u1.jpg"/> </div> </p>