Community-sited ambient air quality network, Mississippi and western Alabama, 2025–2026: data and analysis code

This deposit contains ambient air quality measurements from a community-sited monitoring network operating at nine monitoring sites across eight communities in Mississippi and western Alabama between 28 March 2025 and 22 July 2026, together with the complete analysis pipeline that produces every table and figure in the paper. CONTENTS data/ — processed daily series (13,440 observations) and hourly series (70,234 observations) for PM2.5, ozone, total volatile organic compounds and meteorology, each observation carrying a quality-control flag and reason. data/raw/ contains the original instrument exports, unmodified. tables/ — the result tables reported in the paper and the intermediate outputs they derive from. figures/ — the figures as published, at 600 dpi. code/ — twelve R scripts, to be run in the order given in the README. DATA STRUCTURE Nothing is deleted. Every raw value is retained alongside a flag and the reason it was flagged, so any analysis can be reproduced with or without flagged observations. Four quality-control rules were applied: physical plausibility limits, temperature sensor drift, detection floor, and sustained runs of implausibly low values. Quality control flagged 3.1% of daily observations; 53 of 63 site-variable series carry no flags at all. COORDINATE RESOLUTION Monitors were hosted voluntarily on private and institutional property. Exact deployment coordinates are therefore not included; coordinates in the code and tables are reduced to two decimal places, approximately one kilometre. Distances to regulatory monitors recomputed from these values may differ from the published figures by up to roughly one kilometre. Investigators requiring exact coordinates for verification should contact the corresponding author. EPA reference monitor coordinates are public and are given at full precision. REFERENCE DATA Regulatory monitor data are not redistributed. They are publicly available from the United States Environmental Protection Agency Air Quality System and can be retrieved with code/epa_pull.R, which requires a free API key. KNOWN INSTRUMENT ISSUES Documented in the paper and flagged in the data: a PM2.5 unit at Quitman that failed at both extremes of its range; temperature sensor drift at Jackson-1 from November 2025; a step change in VOC at Epes reflecting monitor relocation rather than a change in air quality; ozone baseline offsets near +25 ppb at Jackson-1 and Epes. See the README for the full list. Measurements are returned to participating communities through quarterly reports generated from this same dataset, available at https://communitynoiselab.org/ Supported by the National Institutes of Health (R01ES036565).