MedicalResearch.com Interview with:
Qian Di, M.S, Doctoral Student
Department of Environmental Health and
Francesca Dominici, Ph.D.
Principal Investigator of this study
Professor of Biostatistics
co-Director of the Harvard Data Science Initiative
Harvard T.H. Chan School of Public Health
MedicalResearch.com: What is the background for this study? What are the main findings?
Response: The Clean Air Act requires Environmental Protection Agency to set National Ambient Air Quality Standard (NAAQS). Currently the annual NAAQS for PM2.5 is 12 microgram per cubic meter; and there is no annual or seasonal ozone standard. However, is current air quality standard stringent enough to protect human health? This is our main motivation.
We conducted the largest attainable cohort study, including over 60 million Medicare participants, to investigate the association between long-term exposure to ozone/PM2.5 and all-cause mortality.
We found significant harmful effect of PM2.5 even below current NAAQS. Each 10 microgram per cubic meter increase in PM2.5 is associated with 13.6% (95% CI: 13.1%~14.1%) increase in all-cause mortality. For ozone, 10 ppb increase in ozone exposure is associated with 1.1% (95% CI: 1.0%~1.2%) increase in mortality. Also, there is no appreciable level below which mortality risk tapered off. In other words, there is no “safe” level for PM2.5 and ozone.
In other words, if we would reduce the annual average of PM2.5 by just 1 microgram per cubic meter nationwide, we should save 12,000 lives among elder Americans every year; 5 microgram — 63,817 lives every year. Similarly, if we would reduce the annual summer average of ozone by just 1 ppb nationwide, we would save 1,900 lives every year; 5 ppb — 9537 lives.
Besides, we found black people, males and people of low SES are more vulnerable to air pollution.