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Abstract
Ambient particulate matter (PM) pollution in China continues to be a major public
health challenge. With the release of the new WHO air quality guidelines in 2021,
there is an urgent need for China to contemplate a revision of air quality standards
(AQS). In the recent decade, there has been an increase in epidemiological studies
on PM in China. A comprehensive evaluation of such epidemiological evidence among
the Chinese population is central for revision of the AQS in China and in other developing
countries with similar air pollution problems. We thus conducted a systematic review
on the epidemiological literature of PM published in the recent decade. In summary,
we identified the following: (1) short-term and long-term PM exposure increase mortality
and morbidity risk without a discernible threshold, suggesting the necessity for continuous
improvement in air quality; (2) the magnitude of long-term associations with mortality
observed in China are comparable with those in developed countries, whereas the magnitude
of short-term associations are appreciably smaller; (3) governmental clean air policies
and personalized mitigation measures are potentially effective in protecting public
and individual health, but need to be validated using mortality or morbidity outcomes;
(4) particles of smaller size range and those originating from fossil fuel combustion
appear to show larger relative health risks; and (5) molecular epidemiological studies
provide evidence for the biological plausibility and mechanisms underlying the hazardous
effects of PM. This updated review may serve as an epidemiological basis for China’s
AQS revision and proposes several perspectives in designing future health studies.
Graphical abstract
Public summary
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Acute effects of PM are smaller in China compared with developed countries
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Health effects caused by PM depend on particle composition, source, and size
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There are no thresholds for the health effects of PM
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Mechanistic studies support the biological plausibility of PM’s health effects
Summary Background Rigorous analysis of levels and trends in exposure to leading risk factors and quantification of their effect on human health are important to identify where public health is making progress and in which cases current efforts are inadequate. The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019 provides a standardised and comprehensive assessment of the magnitude of risk factor exposure, relative risk, and attributable burden of disease. Methods GBD 2019 estimated attributable mortality, years of life lost (YLLs), years of life lived with disability (YLDs), and disability-adjusted life-years (DALYs) for 87 risk factors and combinations of risk factors, at the global level, regionally, and for 204 countries and territories. GBD uses a hierarchical list of risk factors so that specific risk factors (eg, sodium intake), and related aggregates (eg, diet quality), are both evaluated. This method has six analytical steps. (1) We included 560 risk–outcome pairs that met criteria for convincing or probable evidence on the basis of research studies. 12 risk–outcome pairs included in GBD 2017 no longer met inclusion criteria and 47 risk–outcome pairs for risks already included in GBD 2017 were added based on new evidence. (2) Relative risks were estimated as a function of exposure based on published systematic reviews, 81 systematic reviews done for GBD 2019, and meta-regression. (3) Levels of exposure in each age-sex-location-year included in the study were estimated based on all available data sources using spatiotemporal Gaussian process regression, DisMod-MR 2.1, a Bayesian meta-regression method, or alternative methods. (4) We determined, from published trials or cohort studies, the level of exposure associated with minimum risk, called the theoretical minimum risk exposure level. (5) Attributable deaths, YLLs, YLDs, and DALYs were computed by multiplying population attributable fractions (PAFs) by the relevant outcome quantity for each age-sex-location-year. (6) PAFs and attributable burden for combinations of risk factors were estimated taking into account mediation of different risk factors through other risk factors. Across all six analytical steps, 30 652 distinct data sources were used in the analysis. Uncertainty in each step of the analysis was propagated into the final estimates of attributable burden. Exposure levels for dichotomous, polytomous, and continuous risk factors were summarised with use of the summary exposure value to facilitate comparisons over time, across location, and across risks. Because the entire time series from 1990 to 2019 has been re-estimated with use of consistent data and methods, these results supersede previously published GBD estimates of attributable burden. Findings The largest declines in risk exposure from 2010 to 2019 were among a set of risks that are strongly linked to social and economic development, including household air pollution; unsafe water, sanitation, and handwashing; and child growth failure. Global declines also occurred for tobacco smoking and lead exposure. The largest increases in risk exposure were for ambient particulate matter pollution, drug use, high fasting plasma glucose, and high body-mass index. In 2019, the leading Level 2 risk factor globally for attributable deaths was high systolic blood pressure, which accounted for 10·8 million (95% uncertainty interval [UI] 9·51–12·1) deaths (19·2% [16·9–21·3] of all deaths in 2019), followed by tobacco (smoked, second-hand, and chewing), which accounted for 8·71 million (8·12–9·31) deaths (15·4% [14·6–16·2] of all deaths in 2019). The leading Level 2 risk factor for attributable DALYs globally in 2019 was child and maternal malnutrition, which largely affects health in the youngest age groups and accounted for 295 million (253–350) DALYs (11·6% [10·3–13·1] of all global DALYs that year). The risk factor burden varied considerably in 2019 between age groups and locations. Among children aged 0–9 years, the three leading detailed risk factors for attributable DALYs were all related to malnutrition. Iron deficiency was the leading risk factor for those aged 10–24 years, alcohol use for those aged 25–49 years, and high systolic blood pressure for those aged 50–74 years and 75 years and older. Interpretation Overall, the record for reducing exposure to harmful risks over the past three decades is poor. Success with reducing smoking and lead exposure through regulatory policy might point the way for a stronger role for public policy on other risks in addition to continued efforts to provide information on risk factor harm to the general public. Funding Bill & Melinda Gates Foundation.
Although exposure to cigarette smoking and air pollution is common, the current prevalence of chronic obstructive pulmonary disease (COPD) is unknown in the Chinese adult population. We conducted the China Pulmonary Health (CPH) study to assess the prevalence and risk factors of COPD in China.
[1
]School of Public Health, Key Lab of Public Health Safety of the Ministry of Education
and NHC Key Lab of Health Technology Assessment, Shanghai Institute of Infectious
Disease and Biosecurity, Fudan University, Shanghai 200032, China
[2
]Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland,
MD 21205, USA
[3
]Children’s Hospital of Fudan University, National Center for Children’s Health, Shanghai
201102, China
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