Accounting for toxicity

Assistant Professor Lucy Qiu published a news article in Nature Energy on her recent analysis, also in Nature Energy, demonstrating the importance for policy-makers and industry leaders to evaluate air pollution toxicity in residential areas due to fossil fuel use versus from coal-burning energy generation. Previously not understood, this analysis highlights the need to address emissions comprehensively and to not look solely at major emitters, such as coal-burning. Based on this new data, it is clear that, when it comes to toxicity, residential activity, such as stove usage, can have a much higher impact on the health and wellbeing of the public.

The article was developed in partnership Yi David Wang from Credit Suisse Economics in Hong Kong, China and Jiahai Yuan from School of Economics and Management at the North China Electric Power University in Beijing, China. Read the whole article below or from its original source: Nature Energy.

-----

Accounting for toxicity

[This article was originally published on the Nature Energy "News & Views" website]

BY: Yueming "Lucy" Qiu, Yi David Wang & Jiahai Yuan in Nature Energy

Air pollution policy is often focused on controlling mass emissions, neglecting the differential health impacts from sources like residential particulate matter. A study now shows that the impacts from residential emissions are significantly higher compared with coal-fired power plants in China when toxicity is considered.

FEBRUARY 10, 2022 -- It is widely known that the combustion of solid fuels can generate air pollution, in particular particulate matter. Particulate matter (PM) can come from burning coals in coal-fired power plants (CFPPs) as well as from burning coal or biomass for the purpose of residential heating or cooking, and can generate a negative impact on human health. The difference in the toxicity levels of PM emitted from CFPPs versus the residential sector is not well understood. As a result, PM pollution control strategy has primarily been focused on reducing mass emissions. This can lead to the hidden costs of residential PM being largely underestimated, causing suboptimal allocation of air pollution control efforts and imbalanced progress of PM control in different sectors. There has been a significant decrease in PM emissions from CFPPs worldwide due to technological upgrades, retirement of old generating units, and tightening of environmental regulation1. Particulate matter control in the residential sector has received much less attention, despite being the largest source of PM2.5 (PM less than 2.5 micrometres in size) emissions worldwide2.

Now, in Nature Energy, Qing Li at Fudan University and colleagues report a large difference in toxicity of inhalable PM emitted from solid-fuel use in the residential sector and CFPPs in China3. Based on field sampling and laboratory analysis in China as well as air-quality simulations, the main conclusion from this work is that the residential sector contributed about 200-fold higher population-weighted toxic-potency-adjusted PM2.5 exposure compared with CFPPs in China.

The different levels of toxicity from PM are a result of different combinations of chemical composition. Owing to the lower combustion efficiency of solid-fuel burning in the residential sector, residential PM consists of higher concentrations of chemicals with higher toxicity levels. Carbonaceous matter including organic matter and elemental carbon comprise the major components of PM from the residential sector, which can have larger negative health effects, while CFPP-emitted PM is dominated by inorganic chemicals such as water-soluble ions and elements. Intuitively, the results imply that air pollution control should not only use mass emission reduction as the sole target, but also incorporate the toxicities of PM originating from domestic sources.

It should be fully recognized in policy development that PM-emission reduction and carbon-emission reduction are not identical goals, and that differing toxicity levels of PM emissions from residential and CFPP sources should be considered when China is trying to reduce its reliance on coal. Specifically, discouraging residential usage of coal can not only help with the reduction in coal usage, but also have a greater marginal effect on citizens’ health. It can also mitigate some of the near-term electricity supply disruptions from CFPPs, especially given that the amount of coal usage in the residential sector is non-trivial4,5 — the residential sector was responsible for at least 1.94% of total coal consumption in China in 20186. If authorities can incentivize residents to switch away from direct coal and biomass usage in their heating and cooking needs and towards electricity and natural gas via the necessary infrastructure investment, then reductions to carbon emission and PM emission might be achieved with less drastic disruptions to electricity supply than coal drawdown. Instead of focusing predominantly on CFPPs, considering domestic fuel use gives authorities other policy options that are more pro-growth and pro-health.

In developing countries, current efforts to control air pollution are mainly focused on CFPPs and on large industrial units because they are the largest consumers of solid fuels. Yet, if residential usage of solid fuels is less efficient and more harmful per unit of consumption, it makes sense to have policies that shift such usage away from the residential sector and in turn allow more breathing room—quite literally—for everyone. Currently, around 2.6 billion people worldwide still use kerosene and solid fuels such as coal and biomass for cooking7, some likely out of necessity due to insufficient electricity coverage or other related infrastructure shortcomings. It is estimated that worldwide household solid-fuel use can cause about 3.8 million premature deaths each year7 and is responsible for 91.5 million disability-adjusted life-years8. The estimates from the epidemiology literature have played an important role in facilitating the transition to clean fuel use by households. The findings from Qing Li and colleagues add further evidence in support of the tighter control of PM pollution from residential solid-fuel use.

Compared with epidemiology literature that provides statistical evidence of the association between solid-fuel use and health outcomes, the approach taken by Qing Li and colleagues provides a more direct measurement of the actual toxic components of PM. More field sampling and laboratory studies of the toxicity levels of PM in other countries are needed, especially in developing countries such as India, Nepal, Nigeria and Kenya, where residential energy use still predominates2,9,10.

The finding of Qing Li and colleagues also has important implications for refining the cost and benefit analysis of the clean-energy transition. This study is important for refining the benefit estimates of carbon and PM emission control from reducing solid fuel in the residential sector. A key takeaway from this work is that the benefits of the residential clean-energy transition are currently underestimated, due to ignorance of the much higher toxicity level of PM emissions in the residential sector compared with that from CFPPs. Future analysis is needed to comprehensively evaluate the net benefits after considering the costs of PM control strategies in different sectors.

References

1. Tang, L. et al. Nat. Energy 4, 929–938 (2019). Article Google Scholar 

2. Weagle, C. L. et al. Environ. Sci. Technol. 52, 11670–11681 (2018). Google Scholar 

3. Qing, Li. et al. Nat. Energy https://doi.org/10.1038/s41560-021-00951-1 (2022).

4. He, G. et al. One Earth 3, 187–194 (2020). Article Google Scholar 

5. China Dispersed Coal General Management Report 2021 (Institute of Energy, Peking University, 2021); https://energy.pku.edu.cn/docs//2021-11/d584da0a5fd64e149bf7b2458d3c9080.pdf

6. National Data (National Bureau of Statistics of China, 2021); https://data.stats.gov.cn/easyquery.htm?cn=C01

7. Household Air Pollution and Health (World Health Organization, 2021); https://www.who.int/news-room/fact-sheets/detail/household-air-pollution-and-health

8. State of Global Air/2020 (Health Effects Institute, Boston, MA, USA, 2020); https://www.stateofglobalair.org

9. Conibear, L., Butt, E. W., Knote, C., Arnold, S. R. & Spracklen, D. V. Nat .Commun. 9, 617 (2018). Article Google Scholar 

10. Lacey, F. G., Henze, D. K., Lee, C. J., van Donkelaar, A. & Martin, R. V. Proc. Natl Acad. Sci. USA 114, 1269–1274 (2017). Article Google Scholar