Global mortality from outdoor fine particle pollution generated by fossil fuel combustion: Results from GEOS-Chem

https://doi.org/10.1016/j.envres.2021.110754Get rights and content

Highlights

  • Fossil fuel combustion emits particulate matter (PM2.5) harmful to public health.

  • We use a re-evaluated concentration-response function (CRF).

  • We estimate 10.2 million global excess deaths in 2012 due to PM2.5 from this source.

  • 62% of deaths are in China (3.9 million) and India (2.5 million).

  • Our estimate is more than double the GBD reports, due to the updated CRF we use.

Abstract

The burning of fossil fuels – especially coal, petrol, and diesel – is a major source of airborne fine particulate matter (PM2.5), and a key contributor to the global burden of mortality and disease. Previous risk assessments have examined the health response to total PM2.5, not just PM2.5 from fossil fuel combustion, and have used a concentration-response function with limited support from the literature and data at both high and low concentrations. This assessment examines mortality associated with PM2.5 from only fossil fuel combustion, making use of a recent meta-analysis of newer studies with a wider range of exposure. We also estimated mortality due to lower respiratory infections (LRI) among children under the age of five in the Americas and Europe, regions for which we have reliable data on the relative risk of this health outcome from PM2.5 exposure. We used the chemical transport model GEOS-Chem to estimate global exposure levels to fossil-fuel related PM2.5 in 2012. Relative risks of mortality were modeled using functions that link long-term exposure to PM2.5 and mortality, incorporating nonlinearity in the concentration response. We estimate a global total of 10.2 (95% CI: −47.1 to 17.0) million premature deaths annually attributable to the fossil-fuel component of PM2.5. The greatest mortality impact is estimated over regions with substantial fossil fuel related PM2.5, notably China (3.9 million), India (2.5 million) and parts of eastern US, Europe and Southeast Asia. The estimate for China predates substantial decline in fossil fuel emissions and decreases to 2.4 million premature deaths due to 43.7% reduction in fossil fuel PM2.5 from 2012 to 2018 bringing the global total to 8.7 (95% CI: −1.8 to 14.0) million premature deaths. We also estimated excess annual deaths due to LRI in children (0–4 years old) of 876 in North America, 747 in South America, and 605 in Europe. This study demonstrates that the fossil fuel component of PM2.5 contributes a large mortality burden. The steeper concentration-response function slope at lower concentrations leads to larger estimates than previously found in Europe and North America, and the slower drop-off in slope at higher concentrations results in larger estimates in Asia. Fossil fuel combustion can be more readily controlled than other sources and precursors of PM2.5 such as dust or wildfire smoke, so this is a clear message to policymakers and stakeholders to further incentivize a shift to clean sources of energy.

Introduction

The burning of fossil fuels – especially coal, petrol, and diesel – is a major source of airborne particulate matter (PM) and ground-level ozone, which have both been implicated as key contributors to the global burden of mortality and disease (Apte et al., 2015; Dedoussi and Barrett, 2014; Lim et al., 2012). A series of studies have reported an association between exposure to air pollution and adverse health outcomes (Brook et al., 2010), even at low exposure levels (<10 μg m−3, the current World Health Organization, WHO, guideline) (Di et al., 2017). The Global Burden of Diseases, Injuries, and Risk Factors Study 2015 (GBD, 2015) identified ambient air pollution as a leading cause of the global disease burden, especially in low-income and middle-income countries (Forouzanfar et al., 2016). Recent estimates of the global burden of disease suggest that exposure to PM2.5 (particulate matter with an aerodynamic diameter < 2.5 μm) causes 4.2 million deaths and 103.1 million disability-adjusted life-years (DALYs) in 2015, representing 7.6% of total global deaths and 4.2% of global DALYs, with 59% of these in east and south Asia Cohen et al. (2017).

A series of newer studies conducted at lower concentrations and at higher concentrations have reported higher slopes than incorporated into the GBD using the integrated exposure–response (IER) curve (Burnett et al., 2014). These studies examined mortality due to exposure to PM2.5 at concentrations below 10 μg m−3 in North America (Di et al., 2017; Pinault et al., 2016) and above 40 μg m−3 in Asia (Katanoda et al., 2011; Tseng et al., 2015; Ueda et al., 2012; Wong et al., 2015, 2016; Yin et al., 2017). Here we have used a concentration-response curve from a recently published meta-analysis of long-term PM2.5 mortality association among adult populations which incorporates those new findings at high and low PM2.5 concentrations (Vodonos et al., 2018). We also focus our study on the health impacts of fossil-fuel derived PM2.5. In contrast, GBD reports only the health impacts of total PM2.5 and does not distinguish mortality from fossil-fuel derived PM2.5 and that from other kinds of PM2.5, including dust, wildfire smoke, and biogenically-sourced particles. We focus only on PM2.5 since recent studies have provided mixed results on the link between ozone and mortality (Atkinson et al., 2016) and there does not exist a global coherent concentration-response function (CRF) for ozone.

The developing fetus and children younger than 5 years of age are more biologically and neurologically susceptible to the many adverse effects of air pollutants from fossil-fuel combustion than adults. This differential susceptibility to air pollution is due to their rapid growth, developing brain, and immature respiratory, detoxification, immune, and thermoregulatory systems (Bateson and Schwartz, 2008; Perera, 2018). Children also breathe more air per kilogram of body weight than adults, and are therefore more exposed to pollutants in air (WHO, 2006; Xu et al., 2012). The WHO estimated that in 2012, 169,000 global deaths among children under the age of 5 were attributable to ambient air pollution (WHO, 2016). Further estimation of the burden of mortality due to PM2.5 (particularly from anthropogenic sources) among the young population would highlight the need for intervention aimed at reducing children's exposure.

Using the chemical transport model GEOS-Chem, we quantified the number of premature deaths attributable to ambient air pollution from fossil fuel combustion. Improved knowledge of this very immediate and direct consequence of fossil fuel use provides evidence of the benefits to current efforts to cut greenhouse gas emissions and invest in alternative sources of energy. It also helps quantify the magnitude of the health impacts of a category of PM2.5 that can be more readily controlled than other kinds of PM2.5 such as dust or wildfire smoke.

Section snippets

Calculation of surface PM2.5 concentrations

Previous studies examining the global burden of disease from outdoor air pollution have combined satellite and surface observations with models to obtain improved estimates of global annual mean concentrations of PM2.5 (Shaddick et al., 2018). However, the goal of such studies was to quantify the health response to PM2.5 from all sources, both natural and anthropogenic (Brauer et al., 2016, Cohen et al., 2017). Here the focus of our study is on surface ambient PM2.5 generated by fossil fuel

Impact of fossil fuel use on PM2.5

Fig. 1 shows the difference between global GEOS-Chem PM2.5 with and without fossil fuel emissions, plotted as the annual mean for 2012. Results show large contributions of 50–100 μg m−3 in PM2.5 over China and India, with smaller increments of 10–50 μg m−3 over large swaths of the United States and Europe, industrialized countries in Africa (South Africa and Nigeria), and along the North African coastline due to European pollution.

Global assessment of mortality attributable to PM2.5

Based on the annual PM2.5 simulation with and without global

Discussion

We used the chemical transport model GEOS-Chem to quantify the global mortality attributed to PM2.5 air pollution from fossil fuel combustion. Using the updated concentration response relationship between relative mortality and airborne PM2.5, we estimated global premature mortality in 2012 of 10.2 million per year from fossil fuel combustion alone. China has the highest burden of 3.91 million per year, followed by India with 2.46 million per year. These estimates carry large uncertainty (e.g.,

Conclusions

The effects of CO2-driven climate change on human health and welfare are complex, ranging from greater incidence of extreme weather events, more frequent storm-surge flooding, and increased risk of crop failure (Duffy et al., 2019). One consequence of increasing reliance on fossil fuel as an energy source that has thus far received comparatively little attention is the potential health impact of the pollutants co-emitted with the greenhouse gas CO2. Such pollutants include PM2.5 and the

Author contribution

K. Vohra and A. Vodonos carried out the health impact calculations guided by J. Schwartz. E. A. Marais and M. P. Sulprizio performed GEOS-Chem simulations. L. J. Mickley oversaw the project. All authors contributed to writing the manuscript.

Data availability

GEOS-Chem code and output are available at the GEOS-Chem website (http://acmg.seas.harvard.edu/geos_chem.html) and upon request.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgments

This study was funded by the Wallace Global Fund, the Environment and Health Fund (EHF) Israel, and a University of Birmingham Global Challenges Fund PhD studentship awarded to KV. This publication was made possible by USEPA grant RD-835872. Its contents are solely the responsibility of the grantee and do not necessarily represent the official views of the USEPA. Further, USEPA does not endorse the purchase of any commercial products or services mentioned in the publication.

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    Now at: Department of Geography, University College London, London, UK.

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