Fine particulate matter (PM1) air pollution in summer season over Nanjing is more and more dominated by secondary aerosols shaped by sunlight-driven photochemical reactions and humidity-dependent atmospheric chemistry, slightly than direct emissions from site visitors a
Researchers reveal the important position of secondary species in heavier particulate matter air pollution
BOSTON, MA, UNITED STATES, May 25, 2026 /EINPresswire.com/ — Researchers in China studied summer season PM1 air pollution in Nanjing and discovered that it’s now dominated (~70%) by secondary formation slightly than direct emissions. Photochemical reactions drive sulfate and secondary natural aerosols, whereas humidity controls nitrate formation. They recognized a metamorphosis pathway from major emissions to aged aerosols and confirmed that climate strongly influences air pollution chemistry.
Air air pollution brought on by high-quality particulate matter stays one of the world’s most severe environmental and public well being challenges. Although China has achieved main reductions in PM2.5 air pollution over the previous decade by stricter emissions controls, scientists are more and more discovering that the composition of city air air pollution is altering. Instead of being dominated primarily by particles emitted instantly from automobiles, trade, and combustion sources, fashionable summertime air pollution is now more and more pushed by secondary pollution shaped by chemical reactions within the environment.
A brand new examine by Professor Xinlei Ge and his workforce on the Nanjing University of Information Science and Technology, China, has supplied recent perception into how these advanced atmospheric processes form air high quality in a single of China’s largest city areas. The paper was made out there on-line on March 27, 2025, in Volume 159, Issue 1 of the Journal of Environmental Sciences.
Prof. Ge and workforce performed detailed measurements of submicron airborne particles (PM1) in Nanjing in the course of the summer season of 2022 utilizing superior real-time aerosol mass spectrometry. Their evaluation centered on secondary natural aerosols, sulfate, nitrate, natural nitrogen compounds, organosulfates, and polycyclic fragrant hydrocarbons (PAHs), all of which affect air high quality, local weather, and human well being.
The workforce discovered that secondary pollution accounted for practically 70% of the measured PM1 mass, demonstrating that atmospheric chemical reactions now play a dominant position in summer season haze formation. Sunlight-driven photochemical reactions strongly promoted the formation of sulfate and secondary natural aerosols, whereas humid circumstances favored nitrate formation.
“Our findings show that summer aerosol pollution is no longer controlled mainly by direct emissions,” stated Prof. Ge. “Secondary chemical formation processes in the atmosphere have become increasingly important as primary particle emissions continue to decline.”
They recognized two distinct varieties of secondary natural aerosols. One kind shaped quickly in the course of the early afternoon by recent photochemical reactions, whereas the second represented extra aged and oxidized particles that accrued later within the day. The outcomes recommend that major natural particles emitted from site visitors, cooking, and industrial actions can chemically rework into more and more oxidized secondary aerosols as they age within the environment.
The examine additionally highlighted the totally different environmental circumstances that management main pollutant species. Sulfate formation was strongly linked to photochemical oxidation below excessive daylight circumstances, whereas nitrate formation depended extra closely on humidity, heterogeneous reactions, and gas-to-particle partitioning processes. During cooler and extra humid durations, nitrate concentrations elevated considerably and contributed to heavier PM air pollution episodes.
“Humidity and temperature can dramatically change the chemical pathways that dominate particulate pollution,” stated lead creator Yuanjie Shan. “This means pollution-control strategies may need to adapt dynamically to different weather conditions.”
The workforce additionally investigated a number of hazardous natural compounds. Organic nitrogen species had been discovered to originate largely from site visitors and industrial emissions, whereas organosulfates appeared to type primarily by weak aqueous-phase reactions below humid circumstances. PAHs, that are related to incomplete combustion and potential well being dangers, had been primarily linked to automobile emissions, particularly diesel site visitors.
Importantly, the researchers noticed proof that sunlight-driven oxidation might assist take away PAHs from the environment throughout afternoon hours, doubtlessly changing them into secondary natural aerosol merchandise.
“Our results suggest that reducing PM2.5 pollution will require more than simply lowering direct emissions,” Prof. Ge added. “Future mitigation efforts must also target the atmospheric chemistry that drives secondary aerosol formation.”
The findings present new perception into how city air air pollution is evolving in quickly creating areas and might assist policymakers design simpler methods for bettering air high quality and defending public well being.
Reference
Title of unique paper: Chemical traits of high-quality aerosols and related speciated natural compounds in summer season Nanjing, China
Journal: Journal of Environmental Sciences
DOI: https://doi.org/10.1016/j.jes.2025.03.044
About the University
Nanjing University of Information Science and Technology (NUIST) is a nationally acknowledged college in China identified for its strengths in atmospheric science, environmental analysis, info expertise and engineering. Based in Nanjing, the college is dedicated to advancing scientific discovery and innovation whereas addressing international challenges associated to local weather, surroundings and sustainable growth. Through world-class analysis, worldwide collaboration and interdisciplinary training, NUIST helps the event of options that profit society and enhance understanding of the pure world.
Website: https://en.nuist.edu.cn/mainm.htm
About Professor Xinlei Ge
Xinlei Ge is a Professor of Atmospheric Chemistry affiliated with each Nanjing University of Information Science and Technology and Anhui Jianzhu University. His analysis focuses on aerosols, air air pollution, and atmospheric processes, with explicit curiosity in how airborne particles type and evolve in city environments. Through area observations and superior analytical methods, his work contributes to bettering air high quality and understanding the environmental impacts of atmospheric air pollution.
Funding info
This work was supported by the National Natural Science Foundation of China (grant numbers: 22361162668 and 42021004) and the National Key Research and Development Program of China (grant quantity: 2023YFC3706203).
Hanqin Tian
Boston College
+1 617-552-3664
[email protected]
Legal Disclaimer:
EIN Presswire gives this information content material “as is” with out guarantee of any type. We don’t settle for any duty or legal responsibility
for the accuracy, content material, pictures, movies, licenses, completeness, legality, or reliability of the knowledge contained on this
article. If you may have any complaints or copyright points associated to this text, kindly contact the creator above.
