エチオピアの大気汚染を詳細に解析、NASAの観測網が長期データを提供（NASA Mission Studies Air Pollution Over Ethiopia）

2026-08-17 NASA

NASAのMAIA（Multi-Angle Imager for Aerosols）プロジェクトは、エチオピア・アディスアベバで10地点に設置した大気質センサーから2022～2025年に収集したデータを分析し、PM2.5とブラックカーボン（すす）の長期的な変動を明らかにした。3年間のPM2.5平均濃度は30 µg/m³で、ブラックカーボン濃度はNASAが観測する米国3都市の約4～9倍だった。交通量が増える時間帯や、たき火を伴う祝祭時にはブラックカーボンが増加し、燃料燃焼と野焼き・たき火など異なる発生源を識別できた。研究は、長期・多地点観測が不足する都市で大気汚染の基準値を構築する重要性を示す。今後は地上センサーと衛星観測を組み合わせ、PM2.5の種類・濃度と健康影響の関係解明、都市の大気質管理に役立てる。

＜関連情報＞

エチオピア、アディスアベバにおける大気中PM2.5濃度および発生源別ブラックカーボン濃度の空間的・時間的傾向 Spatial and Temporal Trends of Ambient PM2.5 and Source-Apportioned Black Carbon in Addis Ababa, Ethiopia

Kyan K. Shlipak;Tesfaye Mamo;L. Drew Hill;Asmamaw Abera;Jeff Blair;Araya Asfaw;David J. Diner;Sina Hasheminassab
ACS ES&T Air Published:July 13, 2026
DOI:https://doi.org/10.1021/acsestair.6c00140

Abstract

Ambient fine particulate matter pollution (PM_2.5) is the leading global environmental risk factor for human health. This study leverages three years (April 2022-March 2025) of continuous, in situ ambient PM_2.5 and black carbon (BC) measurements from the Multi-Angle Imager for Aerosols (MAIA) investigation’s surface monitoring network to characterize particulate air pollution in Addis Ababa, Ethiopia. Continuous PM_2.5 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 PM_2.5 concentration across all 10 sites was 30 μg/m³, and the average BC concentrations were 3.7 μg/m³ and 7.7 μg/m³ at Central and Jacros, respectively. Both PM_2.5 and BC concentrations exhibited strong diurnal and seasonal variation, with peaks during morning traffic and nighttime inversion, especially during the wet season. PM_2.5 levels were highest at sites west of the city center and exceeded the WHO guideline for daily PM_2.5 of 15 μg/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 PM_2.5 and source-apportioned BC in Ethiopia. Findings from this study establish a pollution baseline for this MAIA target area ahead of the satellite’s launch, improving understanding of particulate pollution levels and sources and supporting future assessment of air quality trends in this region.