Effects of Air Pollution on Respiratory Events and Pain Crises among Children with Sickle Cell Disease in New York City

Rationale: The disease burden of sickle cell disease (SCD) is highest among U.S. Black and Hispanic populations, which are often disproportionately represented in communities with poor air quality. There are limited data on the effects of air pollution exposure and social environmental factors on health outcomes in children with SCD. Objectives: The objectives of our study were to examine the associations between air pollution exposure and acute respiratory and vaso-occlusive pain crises (VOCs) and to further study the associations when stratifying by asthma status and neighborhood disadvantages. Methods: We conducted a retrospective study, collecting data on outpatient sick and emergency department visits, hospital admissions for respiratory events (i.e., respiratory tract infections, asthma exacerbation, acute chest syndrome), and hospitalizations for VOCs among children with SCD in a tertiary care center in New York City from 2015 to 2018. Modeled data from the New York City Community Air Survey data using home addresses' estimated street-level annual average exposure to air pollution (i.e., black carbon, particulate matter with an aerodynamic diameter < 2.5 mu m, and nitrogen dioxide). The area deprivation index (ADI) continuous national ranking percentile (1-100) was used, representing a composite index for neighborhood-level social disadvantage. We further dichotomized study participants at the upper tertile (high vs. low ADI). Multivariable Poisson regression in generalized estimating equation models were used to estimate relative risks (RRs) after adjusting for potential covariates. Results: A total of 114 children with SCD were included in this study and had between one and four annual repeated measures of annual average air pollutants over a total of 425 visits. Overall, there were no significant associations between air pollution levels and acute respiratory pain crises and VOCs among children with SCD and when stratified by asthma status. We found significant interactions between air pollution levels and the continuous ADI variable on respiratory outpatient and frequent respiratory outpatient/ED visits (P < 0.1). When stratified by high ADI, increased exposure to particulate matter with an aerodynamic diameter < 2.5 mu m was significantly associated with more frequent respiratory outpatient/emergency department visits among children residing in higher ADI neighborhoods (RR [95% confidence interval], 1.13 [1.01, 1.27]; P < 0.05), but not among those in lower ADI neighborhoods. Increased exposure to nitrogen dioxide was associated with more outpatient respiratory events for children in high ADI neighborhoods (RR [95% confidence interval], 2.74 [1.24, 6.08]; P < 0.05) compared with low ADI neighborhoods. Conclusions: Air pollution exposures increased respiratory complications among children with SCD living in deprived neighborhoods.