{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,14]],"date-time":"2026-08-14T14:30:36Z","timestamp":1786717836338,"version":"build-2736575974"},"reference-count":96,"publisher":"American Chemical Society (ACS)","issue":"8","license":[{"start":{"date-parts":[[2026,7,13]],"date-time":"2026-07-13T00:00:00Z","timestamp":1783900800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by-nc-nd\/4.0\/"}],"funder":[{"DOI":"10.13039\/100006196","name":"Jet Propulsion Laboratory","doi-asserted-by":"publisher","award":["80NM0018D0004"],"award-info":[{"award-number":["80NM0018D0004"]}],"id":[{"id":"10.13039\/100006196","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100000200","name":"United States Agency for International Development","doi-asserted-by":"publisher","id":[{"id":"10.13039\/100000200","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2026,8,14]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:p>Ambient fine particulate matter pollution (PM2.5) is the leading global environmental risk factor for human health. This study leverages three years (April 2022-March 2025) of continuous, in situ ambient PM2.5 and black carbon (BC) measurements from the Multi-Angle Imager for Aerosols (MAIA) investigation\u2019s surface monitoring network to characterize particulate air pollution in Addis Ababa, Ethiopia. Continuous PM2.5 data were collected from 10 PurpleAir sensors deployed across Addis Ababa and calibrated using collocated Beta Attenuation Monitors at two contrasting U.S. Embassy sites (Central and Jacros). Continuous BC data were collected with AethLabs MA350 microAethalometers operating at these two sites. During the study period, the average PM2.5 concentration across all 10 sites was 30 \u03bcg\/m3, and the average BC concentrations were 3.7 \u03bcg\/m3 and 7.7 \u03bcg\/m3 at Central and Jacros, respectively. Both PM2.5 and BC concentrations exhibited strong diurnal and seasonal variation, with peaks during morning traffic and nighttime inversion, especially during the wet season. PM2.5 levels were highest at sites west of the city center and exceeded the WHO guideline for daily PM2.5 of 15 \u03bcg\/m3 on 99% of days. The Aethalometer Model for source apportionment estimated that, on average, 94% of total BC in Addis Ababa was attributable to fossil fuel combustion, while 6% was associated with biomass burning. Directional and trajectory analyses indicate distinct local and regional sources of biomass and fossil fuel BC, including potential long-range transport of shipping emissions from the Gulf of Aden. This study presents, to our knowledge, the first long-term, multisite characterization of continuous PM2.5 and source-apportioned BC in Ethiopia. Findings from this study establish a pollution baseline for this MAIA target area ahead of the satellite\u2019s launch, improving understanding of particulate pollution levels and sources and supporting future assessment of air quality trends in this region.<\/jats:p>","DOI":"10.1021\/acsestair.6c00140","type":"journal-article","created":{"date-parts":[[2026,7,14]],"date-time":"2026-07-14T00:15:33Z","timestamp":1783988133000},"page":"2128-2142","source":"Crossref","is-referenced-by-count":0,"title":["Spatial and Temporal\nTrends of Ambient PM2.5 and Source-Apportioned Black Carbon\nin Addis Ababa, Ethiopia"],"prefix":"10.1021","volume":"3","author":[{"ORCID":"https:\/\/orcid.org\/0009-0002-8365-3631","authenticated-orcid":true,"given":"Kyan K.","family":"Shlipak","sequence":"first","affiliation":[{"name":"California Institute of Technology , , , ,","place":["Pasadena, California, United States, 91109"]},{"name":"Northwestern University , , ,","place":["Evanston, Illinois, United States, 60208"]},{"name":"AethLabs , , ,","place":["San Francisco, California, United States, 94110"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5302-1356","authenticated-orcid":true,"given":"Tesfaye","family":"Mamo","sequence":"additional","affiliation":[{"name":"Addis Ababa University , ,","place":["Addis Ababa, Ethiopia, 1176"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8929-3556","authenticated-orcid":true,"given":"L. Drew","family":"Hill","sequence":"additional","affiliation":[{"name":"AethLabs , , ,","place":["San Francisco, California, United States, 94110"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Asmamaw","family":"Abera","sequence":"additional","affiliation":[{"name":"Debre Berhan University , , ,","place":["Debre Berhan, Ethiopia, 445"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jeff","family":"Blair","sequence":"additional","affiliation":[{"name":"AethLabs , , ,","place":["San Francisco, California, United States, 94110"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Araya","family":"Asfaw","sequence":"additional","affiliation":[{"name":"Addis Ababa University , ,","place":["Addis Ababa, Ethiopia, 1176"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"David J.","family":"Diner","sequence":"additional","affiliation":[{"name":"California Institute of Technology , , , ,","place":["Pasadena, California, United States, 91109"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sina","family":"Hasheminassab","sequence":"additional","affiliation":[{"name":"California Institute of Technology , , , ,","place":["Pasadena, California, United States, 91109"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"316","published-online":{"date-parts":[[2026,7,13]]},"reference":[{"key":"2026081409082003300_cit1","unstructured":"World Health Organization.\n          \n          WHO global Air Quality Guidelines: Particulate\nMatter (PM2.5 and PM10), Ozone, Nitrogen Dioxide, Sulfur Dioxide and\nCarbon Monoxide; World Health Organization, 2021."},{"key":"2026081409082003300_cit2","unstructured":"State of Global Air 2025:\nA Report on Air Pollution and Its Role\nin the World\u2019s Leading Causes of Death; Health Effects Institute, 2025."},{"key":"2026081409082003300_cit3","unstructured":"World Health Organization.\n          .  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