Lockdowns around the world, enforced with the objective of slowing the spread of Covid-19, have also visibly reduced air pollution. How many lives have been saved as a result of reduced pollution? A new study has quantified that for China: An estimated 12,125 deaths were prevented during China’s countrywide ban on traffic mobility between February 10 and March 14. The study found that this is higher than the lives lost to the pandemic — 4,633 as of May 4. The paper was published on Wednesday in ‘Lancet Planetary Health’.
The researchers agreed that the findings cannot be directly applied to other countries but felt that reduction of air pollution levels have likely brought health benefits in those countries, too. “Although our findings cannot be directly applied to other countries due to different severity of and responses to COVID-19, as well as differing air pollution levels and population characteristics, reduced air pollution levels have been detected in other countries such as South Korea, India, Italy, Germany, Spain, and the US after their own lockdowns,” the study’s first author Kai Chen, assistant professor at the Yale School of Public Health, told The Indian Express, by email.
“However,” he added. “I want to point out that this way of having clean air through massive quarantine and travel restrictions is not sustainable and likely to be only temporary for a short period of time.”
THE CALCULATIONS: The estimates are based on changes in daily concentrations of two air pollutants — nitrogen dioxide and PM2.5 — in 367 Chinese cities from January 1, 2016 to March 14, 2020. The researchers calculated the changes in air quality in 2020 (during quarantine versus before quarantine) and compared these findings with corresponding changes in the same periods (lunar calendar) for 2016 to 2019. Accounting for these earlier years helped factor in the already declining pollution levels in China on account of the country’s clean air policy. For calculating the deaths prevented due to reduced levels of these two pollutants, the study used equations based on the findings of another recent study.
THE FINDINGS: Because of the quarantine, nitrogen dioxide was found to have dropped by 22.8 micrograms per cubic metre in Wuhan and 12.9 micrograms/cubic metre in China, while PM2.5 was found to have dropped by 1.4 micrograms/cubic metre (Wuhan) and 18.9 micrograms /cubic metre (China). The improved air quality during the quarantine period, calculations showed, prevented 8,911 nitrogen dioxide-related deaths (65% of these from cardiovascular diseases and COPD) and 3,214 PM2.5-related deaths (73% from cardiovascular diseases and COPD).
THE TAKEAWAY: “The lessons we learn from this dramatic reduction in air pollution (are) that if we can reduce air pollution and address climate change as aggressively as we are fighting COVID19, but in a more sustainable and healthier way (e.g., using clean energy rather than fossil fuels), we can still prevent the enormous health burdens of air pollution and climate change without having the devastating consequences of a coronavirus pandemic,” Chen said. “To move forward, we need to build a more sustainable and climate-friendly society. This will require strong political will, enhanced international cooperation, and unprecedented societal mobilization.”
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LIMITATIONS: The researchers wrote that their estimates should be interpreted with caution because of the potential overlap between deaths caused by PM 2.5 and by nitrogen dioxide, and the effect on mortality rate caused by disruptions in healthcare systems. Other authors of the paper included researchers from the University at Buffalo School of Public Health and Health Professions, and Boston University School of Public Health.
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