Hidden danger: the long-term effect of ultrafine particles on mortality and its sociodemographic disparities in New York State

Although previous studies have shown increased health risks of particulate matters, few have evaluated the long-term health impacts of ultrafine particles (UFPs or PM0.1, ≤ 0.1µm in diameter). This study assessed the association between long-term exposure to UFPs and mortality in New York State (NYS), including total non-accidental and cause-specific mortalities, sociodemographic disparities and seasonal trends. Collecting data from a comprehensive chemical transport model and NYS Vital Records, we used the interquartile range (IQR) and high-level UFPs (≥75% percentile) as indicators to link with mortalities. Our modified difference-in-difference model controlled for other pollutants, meteorological factors, spatial and temporal confounders. The findings indicate that long-term UFPs exposure significantly increases the risk of non-accidental mortality (RR=1.10, 95% CI: 1.05, 1.17), cardiovascular mortality (RR=1.11, 95% CI: 1.05, 1.18) particularly for cerebrovascular (RR=1.21, 95% CI: 1.10, 1.35) and pulmonary heart diseases (RR=1.33, 95% CI: 1.13, 1.57), and respiratory mortality (borderline significance, RR=1.09, 95% CI: 1.00, 1.18). Hispanics (RR=1.13, 95% CI: 1.00, 1.29) and non-Hispanic Blacks (RR=1.40, 95% CI: 1.16, 1.68) experienced significantly higher mortality risk after exposure to UFPs, compared to non-Hispanic Whites. Children under five, older adults, non-NYC residents, and winter seasons are more susceptible to UFPs’ effects. Environmental Implication Ultrafine particles (UFPs) are airborne particles less than 100nm in aerodynamic diameter. The small size allows them to enter the body through lung easily and reach the most distal regions within hours. Compared to larger particles, the large surface area to volume ratio enables UFPs to absorb greater amounts of hazardous metal and organic compounds per unit. Our findings address the severest impact of UFPs on human mortality and the critical need for monitoring and regulating UFP levels in the US. The disparities by demographics on UFP-mortality relationship may help public health agencies target high-risk populations.