{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,7]],"date-time":"2026-04-07T05:25:56Z","timestamp":1775539556293,"version":"3.50.1"},"reference-count":50,"publisher":"MDPI AG","issue":"7","license":[{"start":{"date-parts":[[2021,4,1]],"date-time":"2021-04-01T00:00:00Z","timestamp":1617235200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100000879","name":"Alfred P. Sloan Foundation","doi-asserted-by":"publisher","award":["N\/A"],"award-info":[{"award-number":["N\/A"]}],"id":[{"id":"10.13039\/100000879","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>Satellite-based rapid sweeping screening of localized PM2.5 hotspots at fine-scale local neighborhood levels is highly desirable. This motivated us to develop a random forest\u2013convolutional neural network\u2013local contrast normalization (RF\u2013CNN\u2013LCN) pipeline that detects local PM2.5 hotspots at a 300 m resolution using satellite imagery and meteorological information. The RF\u2013CNN joint model in the pipeline uses three meteorological variables and daily 3 m\/pixel resolution PlanetScope satellite imagery to generate daily 300 m ground-level PM2.5 estimates. The downstream LCN processes the estimated PM2.5 maps to reveal local PM2.5 hotspots. The RF\u2013CNN joint model achieved a low normalized root mean square error for PM2.5 of within ~31% and normalized mean absolute error of within ~19% on the holdout samples in both Delhi and Beijing. The RF\u2013CNN\u2013LCN pipeline reasonably predicts urban PM2.5 local hotspots and coolspots by capturing both the main intra-urban spatial trends in PM2.5 and the local variations in PM2.5 with urban landscape, with local hotspots relating to compact urban spatial structures and coolspots being open areas and green spaces. Based on 20 sampled representative neighborhoods in Delhi, our pipeline revealed an annual average 9.2 \u00b1 4.0 \u03bcg m\u22123 difference in PM2.5 between the local hotspots and coolspots within the same community. In some cases, the differences were much larger; for example, at the Indian Gandhi International Airport, the increase was 20.3 \u03bcg m\u22123 from the coolest spot (the residential area immediately outside the airport) to the hottest spot (airport runway). This work provides a possible means of automatically identifying local PM2.5 hotspots at 300 m in heavily polluted megacities and highlights the potential existence of substantial health inequalities in long-term outdoor PM2.5 exposures even within the same local neighborhoods between local hotspots and coolspots.<\/jats:p>","DOI":"10.3390\/rs13071356","type":"journal-article","created":{"date-parts":[[2021,4,1]],"date-time":"2021-04-01T10:44:01Z","timestamp":1617273841000},"page":"1356","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":19,"title":["Local PM2.5 Hotspot Detector at 300 m Resolution: A Random Forest\u2013Convolutional Neural Network Joint Model Jointly Trained on Satellite Images and Meteorology"],"prefix":"10.3390","volume":"13","author":[{"given":"Tongshu","family":"Zheng","sequence":"first","affiliation":[{"name":"Department of Civil and Environmental Engineering, Duke University, 121 Hudson Hall, Science Dr, Durham, NC 27708, USA"}]},{"given":"Michael","family":"Bergin","sequence":"additional","affiliation":[{"name":"Department of Civil and Environmental Engineering, Duke University, 121 Hudson Hall, Science Dr, Durham, NC 27708, USA"}]},{"given":"Guoyin","family":"Wang","sequence":"additional","affiliation":[{"name":"Amazon Alexa AI, 300 Pine St, Seattle, WA 98181, USA"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1005-6385","authenticated-orcid":false,"given":"David","family":"Carlson","sequence":"additional","affiliation":[{"name":"Department of Civil and Environmental Engineering, Duke University, 121 Hudson Hall, Science Dr, Durham, NC 27708, USA"},{"name":"Department of Biostatistics and Bioinformatics, Duke University Medical Center, Suite 1102 Hock Plaza, 2424 Erwin Rd, Durham, NC 27710, USA"}]}],"member":"1968","published-online":{"date-parts":[[2021,4,1]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"709","DOI":"10.1080\/10473289.2006.10464485","article-title":"Health effects of fine particulate air pollution: Lines that connect","volume":"56","author":"Pope","year":"2006","journal-title":"J. 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