Professor Maosheng of the School of the Environment revealed that there are significant differences in the composition and toxicity of atmospheric particulate matter in Chinese mainland 31 capital cities

Air pollution has become one of
the major environmental challenges facing modern society.
According to the Global burden of Disease report, air pollution caused 4.
9 million deaths worldwide in 2017, of which particulate matter exposure caused 2.
94 million deaths
.
Particulate matter is a complex mixture of different sources and components, resulting in significant differences
in toxicity.
However, air pollution quality standards are based on the concentration of particulate matter, ignoring differences
in particulate matter toxicity.
Recently, the World Health Organization (WHO) lowered the recommended _PM2.
5 concentration from 10 μg/m3 to 5 μg/m3
.
This move does not provide a good analysis of the costs and corresponding health benefits
for different cities.

Fig.
1 Average annual PM 10 concentration vs.
toxicity-adjusted PM₁₀ level

China has made important progress
in air pollution control over the past decade.
However, the current dominant standard for control and evaluation is still the mass concentration of atmospheric particulate matter, and the toxicity of particulate matter has not been taken into account
.
Previously, Professor Yao Maosheng's team at the School of Environmental Science and Engineering at Peking University had found that particle toxicity varied widely in 19 cities around the world (Li et al.
, 2019).

Based on previous laboratory research, the team collected 465 automotive air conditioning filter membranes from 31 major cities in China for analysis
using the same method (automotive air conditioning filter membranes).
The results of dithiothreitol (DTT) experiments showed that there were significant differences in normalized PM toxicity (NIOG) in different cities in China, with the highest particulate toxicity in Changsha (4.
99×^10-3) and the lowest in Yinchuan (7.
72×^10-4) (Fig.
1, 2).

Statistical analysis showed a significant negative correlation between NIOG and annual PM₁₀ concentrations (r = -0.
416, p = 0.
020).

The results also showed that the concentrations of different elements and water-soluble ions in PM in 31 cities in China were several orders of magnitude different (Figures 3, 4).

Our further findings suggest that the toxicity differences are related to differences in the biochemical composition of particulate matter, and components such as fungi and water-soluble_SO42^- in particulate matter may play an important role
in particulate matter toxicity.

Fig.
2 Chinese mainland 31 major cities with potential release of atmospheric particulate matter oxidation (NIOG) (Note: This map is adapted from the standard map of GS (2019) 1673 of the Ministry of Natural Resources, the base map has not been modified in any way, and the standard size is 126*92mm)

In 31 cities in China, qPCR results showed that the total levels of bacteria and fungi in 31 cities in China varied by 10-100 times (Figure 5).

The LAL results showed that PM endotoxin concentrations ranged from 2.
88 EU/mg PM (Hangzhou) to 62.
82 EU/mg PM (Shijiazhuang) (Figure 6).

These results reveal different daily inhalations of fungi and endotoxins
in different cities.
These substances are biological components
of particulate matter that has an important impact on the human body.
Statistical analysis showed that the concentrations of chemical components (water-soluble ions and trace elements) and biological components (fungi, bacteria and endotoxins) in PM were significantly correlated
with some meteorological factors and gaseous pollutants such as_SO2.
Preliminary results from toxicological experiments in the team's lab at the animal level also show significant differences in
the toxicity of particulate matter in these cities.
Therefore, the use of the same particulate matter mass concentration standards to formulate air pollution control policies for different cities in China is obviously one-sided, and there is an imbalance
in control requirements.
For places with high particulate toxicity, the standard requirements for particulate matter concentration can be increased, so that human health
can be better protected.
For cities with relatively low particulate matter toxicity, the standards for particulate matter can be slightly relaxed, and the economy
can be better protected on the basis of protecting human health.
Only by truly considering the difference in toxicity can we achieve precise prevention and control of air pollution (economic and health trade-off).

The results of this research work not only provide the scientific basis for these efforts, but also provide important references
for achieving these goals.

The research results were recently published online in the journal Fundamental Research under the title "Ambient particle composition and toxicity in 31 major cities in China
".
The first author of the paper is Zhang Lu, a doctoral student at the School of Environment, Peking University, and Professor Maosheng of Peking University is the corresponding author
.
This project is mainly supported
by the National Natural Science Foundation of China (grant 92043302) and the National Science Foundation for Outstanding Young Scholars of the National Natural Science Foundation of China (grant 21725701).

Fig.
3 Chinese mainland concentration of water-soluble ions in atmospheric particulate matter in 31 major cities

Fig.
4 Chinese mainland atmospheric particulate matter element concentrations in 31 major cities

Fig.
5 Concentrations of bacteria and fungi in atmospheric particulate matter in Chinese mainland 31 major cities

Fig.
6 Endotoxin concentrations in atmospheric particulate matter Chinese mainland 31 major cities

Related references

Jing Li, Haoxuan Chen, Xinyue Li, Minfei Wang, Xiangyu Zhang, JunjiCao, Fangxia Shen, Yan Wu, Siyu Xu, Hanqing Fan, Guillaume Da, Ru-jin Huang, Jing Wang, Chak K.
Chan, Alma Lorelei De Jesus, Lidia Morawska, and Maosheng Yao （2019）, Differing Toxicity of Ambient P articulate Matter (PM) in Global Cities.
Atmospheric Environment，212, 305-315
。 DOI:https://doi.
org/10.
1016/j.
atmosenv.
2019.
05.
048

Lu Zhang，Maosheng Yao，Ambient particle composition and toxicity in 31 major cities in China，Fundamental Research，DOI：https://doi.
org/10.
1016/j.
fmre.
2022.
10.
004