Advancing Air Quality, Food Security and
Human Health under Global Climate Change
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Transboundary Air Pollution and Health Impacts
Air pollution is one of the serious environmental problems in China, resulting in adverse impacts on both human health and planetary health. Although previous observational research indicated the significant regional nature of particulate matters in China, transboundary air pollution (TAP) within China is yet to understand.

Our research comprehensively assessed the formation, transport and removal processes of TAP in China and apportioned the impacts of emissions in different regions on air quality and public health. We applied state-of-the-art air quality model and measurement to simulate air quality in China. We then adopted an integrated concentration-response function for China to estimate the resultant amount of premature mortality due to air pollution.
Our findings show that domestic TAP, on average, accounted for 27% of the total PM2.5 in China. In Pearl River Delta, local air pollution and TAP contributed 27% and 73%, respectively, to the region’s PM2.5. We estimated that outdoor air pollution leads to ~870,000 (95% CI: 130,000 - 1,500,000) premature mortalities in China in 2010, of which about 18% is attributed to TAP. When a tropical cyclone is approaching to the PRD, the contribution of TAP to Hong Kong air pollutants is increased by 17% - 46%. On the other hand, we found that due to favourable meteorological conditions for long-range transport, the TAP contribution increased during the two recent La Niña events but reduced in the recent two past El Niño events.
Our research estimated ozone (O3) pollution contributed to 0.3 M premature mortalities in China in 2010. Transboundary O3 pollution is significant in southern and northern China and the Yangtze River Delta, while local sources are more linked to the O3 pollution in the Pearl River Delta and the Beijing-Tianjin-Hebei region. Our study proposed the importance of implementing the health-oriented emission control strategy with proper optimization to effectively mitigate O3 pollution problems. Our results show that adjoint-based emission optimization achieved more O3 health benefits by 16 - 27%.
Our findings proved the significant impacts of TAP on public health in China, indicating the need for cross-region co-operation to mitigate the air quality impacts and resultant health problems. Our research team has developed a 3D Real-timE Atmospheric Monitoring System (3DREAMS) using Doppler LiDARs to monitor and analyse the effects of weather on ground surface and upper-level PMs, in particular TAP. The 3DREAMS is the first-of-its-kind long-term monitoring system for studying air pollution. Our publications demonstrated the capabilities of our 3DREAMS on meteorological and air pollution research.
Reference:
1. Gu, Y., & Yim, S. H. L. (2016). The air quality and health impacts of domestic trans-boundary pollution in various regions of China. Environment International, 97, 117-124. https://doi.org/10.1016/j.envint.2016.08.004
Impact Factor: 9.621 (2020)
2. Hou, X., Chan, C. K., Dong, G. H., & Yim, S. H. L. (2019). Impacts of transboundary air pollution and local emissions on PM2.5 pollution in the Pearl River Delta region of China and the public health, and the policy implications. Environmental Research Letters, 14(3), 034005. https://doi.org/10.1088/1748-9326/aaf493
Impact Factor: 6.793 (2020)
3. Luo, M., Hou, X., Gu, Y., Lau, N. C., & Yim, S. H. L. (2018). Trans-boundary air pollution in a city under various atmospheric conditions. Science of The Total Environment, 618, 132-141. https://doi.org/10.1016/j.scitotenv.2017.11.001
Impact Factor: 7.963 (2020)
4. Yim, S. H. L., Hou, X., Guo, J., & Yang, Y. (2019). Contribution of local emissions and transboundary air pollution to air quality in Hong Kong during El Niño-Southern Oscillation and heatwaves. Atmospheric Research, 218, 50-58. https://doi.org/10.1016/j.atmosres.2018.10.021
Impact Factor: 5.369 (2020)
5. Gu, Y., Wong, T. W., Law, C. K., Dong, G. H., Ho, K. F., Yang, Y., & Yim, S. H. L. (2018). Impacts of sectoral emissions in China and the implications: air quality, public health, crop production, and economic costs. Environmental Research Letters, 13(8), 084008. https://doi.org/10.1088/1748-9326/aad138
Impact Factor: 6.793 (2020)
6. Wang, M. Y., Yim, S. H. L., Wong, D. C., & Ho, K. F. (2019). Source contributions of surface ozone in China using an adjoint sensitivity analysis. Science of The Total Environment, 662, 385-392. https://doi.org/10.1016/j.scitotenv.2019.01.116
Impact Factor: 7.963 (2020)
7. Wang, M., Huang, T., Wong, D. C., Ho, K. F., Dong, G., & Yim, S. H. L. (2021). A new approach for health-oriented ozone control strategy: Adjoint-based optimization of NOx emission reductions using metaheuristic algorithms. Journal of Cleaner Production, 312, 127533. https://doi.org/10.1016/j.jclepro.2021.127533
Impact Factor: 9.297 (2020)
8. Yim, S. H. L. (2020). Development of a 3D real-time atmospheric monitoring system (3DREAMS) using Doppler LiDARs and applications for long-term analysis and hot-and-polluted episodes. Remote Sensing, 12(6), 1036. https://doi.org/10.3390/rs12061036
9. Huang, T., Yang, Y., O’Connor, E. J., Lolli, S., Haywood, J., Osborne, M., ... & Yim, S. H. L. (2021). Influence of a weak typhoon on the vertical distribution of air pollution in Hong Kong: A perspective from a Doppler LiDAR network. Environmental Pollution , 276, 116534. https://doi.org/10.1016/j.envpol.2021.116534
10. Huang, T., Yim, S. H. L., Yang, Y., Lee, O. S. M., Lam, D. H. Y., Cheng, J. C. H., & Guo, J. (2020). Observation of turbulent mixing characteristics in the typical daytime cloud-topped boundary layer over Hong Kong in 2019. Remote Sensing, 12(9), 1533. https://doi.org/10.3390/rs12091533
11. Huang, T., Li, Y., Cheng, J. C., Haywood, J., Hon, K. K., Lam, D. H., ... & Yim, S. H. L. (2021). Assessing Transboundary‐local Aerosols Interaction over Complex Terrain Using a Doppler LiDAR Network. Geophysical Research Letters, e2021GL093238. https://doi.org/10.1029/2021GL093238

Acknowledgement:
This section of research project was supported by grant from the Vice-Chancellor’s Discretionary Fund of The Chinese University of Hong Kong (project no.: 4930744).
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