PM_2.5composition and disease aggravation in amyotrophic lateral sclerosis: An analysis of long-term exposure to components of fine particulate matter in New York State

Background: Long-term exposure to fine particulate matter (PM_2.5) has been associated with disease aggravation in amyotrophic lateral sclerosis (ALS). In this study, we characterized long-term exposure to six major PM_2.5components and their individual association with disease aggravation in ALS. Methods: We leveraged 15 years of data from the New York Department of Health Statewide Planning and Research Cooperative System (2000-2014) to calculate annual ALS first hospitalizations in New York State. We used the first hospital admission as a surrogate of disease aggravation and a prediction model to estimate population-weighted annual black carbon, organic matter (OM), nitrate, sulfate, sea salt, and soil concentrations at the county level. We used a multi-pollutant mixed quasi-Poisson model with county-specific random intercepts to estimate rate ratios (RR) of 1-year exposure to each PM_2.5component and disease aggravation in ALS, adjusting for potential confounders. Results: We observed 5,655 first ALS-related hospitalizations. The annual average hospitalization count per county was 6.08 and the average PM_2.5total mass concentration per county was 8.1 μg/m³- below the United States' National Ambient Air Quality Standard of 12 μg/m³. We found a consistent positive association between ALS aggravation and OM (1.17, 95% confidence intervals [CI], 1.11, 1.24 per standard deviation [SD] increase) and a negative association with soil (RR = 0.91, 95% CI, 0.86, 0.97). Conclusion: Our findings suggest that PM_2.5composition may influence its effect on ALS. We found that annual increases in county-level particulate OM may be associated with disease aggravation in ALS, even at PM_2.5levels below current standards.