Variations in ambient airborne carcinogen concentrations (particulate matter; PM _2.5 ) in urban neighborhoods in Rhode Island.

e22514 Background: Fine particulate matter smaller than 2.5 μm in diameter (PM 2.5 ) carries toxic substances including sulfates, hydrocarbons, and heavy metals, penetrating the lungs and bloodstreams. PM 2.5 is associated with increased incidence of lung cancer, and the World Health Organization (WHO) air quality guidelines set acceptable exposure at 5 μg/m 3 annual average and 15 μg/m 3 for the 24-hour limit, not to be exceeded more than 3-4 days yearly. Currently, the United States Environmental Protection Agency defines the standard for PM 2.5 at 9.0 μg/m 3 (annual average) and 35 μg/m 3 (daily limit). Methods: The Breathe Providence Project was created by Brown University researchers to characterize neighborhood-scale air quality. Twenty-five locations across the city of Providence, Rhode Island were selected based on Air Quality Vulnerability Index scores and proximity to high foot traffic public institutions. Environmental Air-Quality and CO2 Network sensor nodes measured local PM 2.5 levels throughout 2023. Data were analyzed as daily, weekly, and monthly averages, and stratified by daytime (5AM to 5PM) and nighttime (5PM to 5AM). Results: In 2023, PM 2.5 daily average values ranged from 1 to 10 μg/m 3 from January to May, with monthly averages of 1 to 3 μg/m 3 . PM 2.5 values peaked during the summer months of June to August, with daily averages as high as 36 μg/m 3 and weekly and monthly averages up to 16 and 9 μg/m 3 , respectively. During these summer months, there were 17 days for which the daily average levels exceeded the WHO daily limit of 15 μg/m 3 . From September to December, daily average values ranged 1 to 16 μg/m 3 , with monthly averages of 4 to 6 μg/m 3 , demonstrating an overall increase in air pollution levels through the year. Nighttime PM 2.5 concentrations were typically 1 to 2 μg/m 3 higher than daytime values. Conclusions: There was seasonal and diurnal variability in PM 2.5 in Providence, with multiple exceedances of WHO guidelines in 2023. Elevated nightly values likely reflect stagnant atmospheric conditions, and the summer peaks may be due to record-breaking 2023 Canadian wildfires, which affected air quality across the eastern United States. The state of Rhode Island has a significantly higher incidence rate of lung cancer of 59 per 100,000, exceeding the national rate of 53. Our study highlights the higher PM 2.5 averages during summer months and the evening, which may be contributing to the higher lung cancer incidence in Rhode Island. Larger studies are needed to investigate this correlation. We propose geospatial mapping of PM 2.5 exposure across different regions in the state, with careful regional quantification of long-term PM 2.5 levels and correlating with lung cancer incidence. These studies could inform us of the spatial patterns of lung cancer risk and help formulate mitigation strategies and actionable maps for health systems and policymakers.