Fine particulate [PM2.5] air pollution
is one of the key public health concerns in developing countries
including China, but the epidemiological evidence about its health
effects is scarce.
In the largest epidemiological study conducted in the developing world, researchers found that as exposures to fine particulate air pollution in 272 Chinese cities increase, so do deaths from cardiovascular and respiratory diseases.
‘As exposures to fine particulate air pollution in 272 Chinese cities increase, so do deaths from cardiovascular and respiratory diseases.’
The researchers reported their results in "Fine Particulate Air Pollution and Daily Mortality: A Nationwide Analysis in 272 Chinese Cities," published online ahead of print in the American Thoracic Society's American Journal of Respiratory and Critical Care Medicine
Senior study author Maigeng Zhou, deputy
director of the National Center for Chronic and Non-communicable Disease
Control and Prevention, Chinese Center for Disease Control and
Prevention, said, "A new monitoring network allowed us to conduct a nationwide
study to evaluate short-term associations between PM2.5 and daily
cause-specific mortality in China."
The researchers found:
* The average annual exposure to PM2.5 in the Chinese cities was 56
micrograms per cubic meter (μg/m3) - well above the World Health
Organization air quality guidelines of 10 μg/m3.
* Each 10 μg/m3 increase in air pollution was associated with a 0.22% increase in mortality from all non-accident related causes.
* Each 10 μg/m3 increase in air pollution was associated with a 0.29% increase in all respiratory mortality and a 0.38%
increase in chronic obstructive pulmonary disease (COPD) mortality.
* Mortality was significantly higher among people age 75 and older and
among people with lower levels of education.
* The association between PM2.5 levels and mortality was stronger in
cities with higher average annual temperatures.
The researchers speculate that differences in educational attainment
may result in environmental health inequalities and access to health
care that affect mortality. In warmer cities, the authors hypothesize
residents may spend more time outdoors and open windows, increasing
their exposure to PM2.5.
The researchers said their study suggests a weaker association
between increases in PM2.5 and mortality than studies conducted in
Europe and North America. They suggest a number of possible explanations
for this difference, including that in most Chinese cities there was a
plateauing of mortality at the highest levels of pollution and the
components of PM2.5 pollution in China may be less toxic than the
components in Europe and North America. Crustal dust from arid lands and
construction make up more PM2.5 pollution in China than it does in
Europe and North America.
In 2013 China began introducing PM2.5 monitoring in urban areas. The
current study analyzed available data between 2013-15. For nearly half
the cities in the study, there was only one year of PM2.5 data
available, and the authors note that a limitation of their study is that
it does not look at the cumulative effect of PM2.5 over many years.
"Our findings may be helpful to formulate public health policies and
ambient air quality standards in developing countries to reduce the
disease burden associated with PM2.5 air pollution," said study
co-author Haidong Kan, professor of public health at Fudan
University in China. "Further massive investigations, especially looking
at the long-term effect studies, are needed to confirm our results and
to identify the most toxic components of PM2.5 in China."