A18-10 Large-Scale Mold Intervention Reduced Asthma Emergency Department Visits in New York City Public Housing Differentially Across Building and Neighborhood Characteristics

Rationale New York City Housing Authority (NYCHA) provides housing to over 400,000 predominantly Black, Hispanic, and low-income residents. Mold complaints in NYCHA are common, and the burden of asthma among residents is high. In 2019, NYCHA implemented ‘Mold Busters,’ a program to remediate mold using evidence-based methods that have previously improved asthma symptoms in small-scale (n < 100) randomized controlled trials. We hypothesized that ‘Mold Busters’ would reduce asthma-related emergency department (ED) visits, and that population, building, neighborhood, and climate vulnerability characteristics would influence the intervention’s efficacy. Methods We obtained 2016-2023, building-level asthma ED visit data among NYCHA residents and a ‘Mold Busters’ unexposed group living in proximate, non-NYCHA lower-income census tracts. We assessed the impact of ‘Mold Busters’ on asthma ED visits using doubly robust differences-in-differences analyses aggregated to pre- (2016-2018) and post- (2021-2023) intervention periods. We obtained resident-reported, building-level mold work order data from NYCHA and applied latent class growth analysis (LCGA) to categorize NYCHA buildings by the trajectory of mold report rates in the post-intervention period. We conducted the differences-in-differences analyses stratified by LCGA groups. Results The ‘Mold Busters’ intervention was associated with an average annual reduction of 9.0 (95% CI: -11.2, -6.7) asthma-related ED visits per 1,000 residents, translating to 2,798 fewer annual ED visits from 2021-2023. LCGA identified five trajectory groups. Each group experienced decreases in report rates following the intervention, however some groups experienced larger decreases than others (Figure 1a). Groups with slower reductions in mold reporting rates were generally larger, older, more likely to lack mechanical ventilation, and more likely to be set in flood zones and higher poverty neighborhoods. Groups with larger reductions in mold complaints (e.g., groups B and D, Figure 1a) also experienced larger reductions in asthma ED visits (Figure 1b). Conclusions Interventions aimed at reducing asthma triggers can be tools to address longstanding asthma disparities. To our knowledge, this is the first large-scale observational study to demonstrate that a city-wide mold intervention in public housing can reduce asthma ED visits. Results highlighting where, when, and for whom the intervention was most effective can inform future interventions.