Particle surface area, ultrafine particle number concentration, and cardiovascular hospitalizations

Abstract

Background and aim: While the human health impacts of larger particulate matter, such as PM10 and PM2.5, have been studied extensively, research regarding ultrafine particles (UFPs or PM0.1) and particle surface area is lacking. This case-crossover study assessed the associations between exposure to particle surface area concentration (PSC) and UFP particle number concentration (UFPnc) and hospital admissions for cardiovascular diseases (CVDs) in New York State (NYS), 2013-2018. Methods: We used a time-stratified case-crossover design to compare the PSC and UFPnc levels between hospitalization days and control days (similar days without admissions) for each CVD case. We utilized NYS hospital discharge data to identify all CVD cases who resided in NYS. We used UFP simulation data from GEOS-Chem, a state-of-the-art chemical transport model, to define PSC and UFPnc. Using a multi-pollutant model and conditional logistic regression, we assessed CVD risk per inter-quartile change of PSC and UFPnc after controlling for meteorological factors, co-pollutants, and time-varying variables. Results: Our results indicate an immediate and robust positive association between PSC and overall CVDs (lag0– lag0-1: 1.0%) and a delayed, lasting effect between UFPnc and CVDs (lag0-3–lag0-6: 0.4%). Exposure to larger PSC was associated with immediate increases in stroke, hypertension, and ischemic heart diseases (0.7%, 0.8%, 0.8%, respectively). The adverse effects of PSC on CVDs were highest among youngest children (0-4 years old), in fall and winter, and during cold temperature days (2.0%, 1.4%, 1.3%, 1.5%, respectively) compared to those on other days. Conclusion: We found an immediate, positive effect of PSC on overall CVDs and a delayed, lasting impact of UFPnc. PSC was a more sensitive indicator than UFPnc. The PSC-related effects were higher among certain CVD subtypes, in the youngest children, in certain seasons, and during cold days. Keywords: ultrafine particles, particle surface area, air pollutants, cardiovascular admission, vulnerability, seasonality