Traffic and combustion emission controls leave cooking as a dominant local source of primary PM1 in megacities
17 affiliations
- 1UK Centre for Ecology & Hydrology, Edinburgh Research Station, Bush Estate, Penicuik, UK
- 2School of Earth and Environmental Sciences, The University of Manchester, Manchester, UK
- 3National Centre for Atmospheric Science, The University of Manchester, Manchester, UK
- 4Department of Chemistry, Colorado State University, Fort Collins, CO USA
- 5Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China
- 6Present Address: School of Earth System Science, Tianjin University, Tianjin, China
- 7Department of Applied Sciences and Humanities, Indira Gandhi Delhi Technical University for Women, Delhi, India
- 8Department of Civil Engineering, Indian Institute of Technology, Roorkee, India
- 9Cooperative Institute for Research in Environmental Sciences (CIRES) and Department of Chemistry, University of Colorado, Boulder, CO USA
- 10TOFWERK AG, Thun, Switzerland
- 11Aerodyne Research Inc, Billerica, MA USA
- 12Zhejiang University, Hangzhou, China
- 13CSIR National Physical Laboratory, New Delhi, India
- 14Department of Natural Sciences, University of Chester, Thornton Science Park, Chester, UK
- 15Present Address: Maastricht University, Maastricht, Limburg Netherlands
- 16Present Address: Tecnologico de Monterrey, Escuela de Ingeniería y Ciencias, Av. General Ramon Corona 2514, Zapopan, Jalisco Mexico
- 17Present Address: UK Centre for Ecology & Hydrology, Maclean Building, Wallingford, UK
Abstract
Megacities frequently suffer from poor air quality, with PM2.5 concentrations routinely exceeding WHO guidelines and elevating the risk of cardiovascular and respiratory disease. Air quality legislation typically targets primary emissions from traffic, a dominant urban source of PM₂.₅. Here, we present direct, chemically resolved quantification of PM₁ emissions from three contrasting megacity neighbourhoods—London, Beijing and Delhi—revealing the magnitude and diversity of urban sources by applying a novel source attribution approach to eddy-covariance flux measurements using aerosol mass spectrometry. In Delhi, traffic and combustion dominate primary PM₁ emissions. In contrast, cooking is the largest source during mealtimes in London and Beijing, contributing up to 83% of midday emissions and 87% in the early evening in London, and up to 61% and 76%, respectively, in Beijing. These findings suggest that air quality legislation in London and Beijing has effectively reduced non-refractory transport and combustion emissions, allowing cooking to emerge as the largest local source of primary non-refractory PM₁. Although cooking is not included in national, European or global emission inventories, recent estimates from the London Atmospheric Emissions Inventory align well with our observations. Together, these results show that the sources dominating primary non-refractory PM₁ emissions differ from those controlling ambient PM1 mass. Although cooking is now the leading primary source in London and Beijing, further reductions in urban PM₁ will depend on mitigating secondary formation processes.
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BibTeX
@article{langford2026traffic,
title = {{Traffic and combustion emission controls leave cooking as a dominant local source of primary PM1 in megacities}},
author = {Ben Langford and Chiara, F. Di Marco and James M. Cash and James D. Allan and Zixuan Cheng and Hugh Coe and Delphine K. Farmer and Pingqing Fu and Ranu Gadi and Bhola Ram Gurjar and Jose L. Jimenez and Joel Kimmel and Dantong Liu and Tuhin Kumar Mandal and Neil J. Mullinger and Gavin J. Phillips and Ernesto Reyes-Villegas and Rutambhara Joshi and Shivani Shivani and Eiko Nemitz},
journal = {Npj Climate and Atmospheric Science},
year = {2026},
month = oct,
doi = {10.1038/s41612-026-01583-6},
url = {https://doi.org/10.1038/s41612-026-01583-6},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Traffic and combustion emission controls leave cooking as a dominant local source of primary PM1 in megacities
AU - Ben Langford
AU - Chiara, F. Di Marco
AU - James M. Cash
AU - James D. Allan
AU - Zixuan Cheng
AU - Hugh Coe
AU - Delphine K. Farmer
AU - Pingqing Fu
AU - Ranu Gadi
AU - Bhola Ram Gurjar
AU - Jose L. Jimenez
AU - Joel Kimmel
AU - Dantong Liu
AU - Tuhin Kumar Mandal
AU - Neil J. Mullinger
AU - Gavin J. Phillips
AU - Ernesto Reyes-Villegas
AU - Rutambhara Joshi
AU - Shivani Shivani
AU - Eiko Nemitz
PY - 2026
DA - 2026/10/23
JO - Npj Climate and Atmospheric Science
DO - 10.1038/s41612-026-01583-6
UR - https://doi.org/10.1038/s41612-026-01583-6
AB - Megacities frequently suffer from poor air quality, with PM2.5 concentrations routinely exceeding WHO guidelines and elevating the risk of cardiovascular and respiratory disease. Air quality legislation typically targets primary emissions from traffic, a dominant urban source of PM₂.₅. Here, we present direct, chemically resolved quantification of PM₁ emissions from three contrasting megacity neighbourhoods—London, Beijing and Delhi—revealing the magnitude and diversity of urban sources by applying a novel source attribution approach to eddy-covariance flux measurements using aerosol mass spectrometry. In Delhi, traffic and combustion dominate primary PM₁ emissions. In contrast, cooking is the largest source during mealtimes in London and Beijing, contributing up to 83% of midday emissions and 87% in the early evening in London, and up to 61% and 76%, respectively, in Beijing. These findings suggest that air quality legislation in London and Beijing has effectively reduced non-refractory transport and combustion emissions, allowing cooking to emerge as the largest local source of primary non-refractory PM₁. Although cooking is not included in national, European or global emission inventories, recent estimates from the London Atmospheric Emissions Inventory align well with our observations. Together, these results show that the sources dominating primary non-refractory PM₁ emissions differ from those controlling ambient PM1 mass. Although cooking is now the leading primary source in London and Beijing, further reductions in urban PM₁ will depend on mitigating secondary formation processes.
SN - 2397-3722
ER -