Storm Warning: America's Earth Science · Episode 8 of 12 · 27 min
Six Cities: The Air That Shortens Your Life
A generation-long study of about 8,000 people in six American towns proved that invisible fine particles in the air were shortening lives, and rewrote the Clean Air Act. The Harvard Six Cities study, published in 1993, became the standard example of value you cannot see, and later fights over its confidential data became the 'secret science' controversy.
Who's who
- Benjamin G. Ferris Jr.Harvard pulmonologist who started the Six Cities study
- Douglas Dockery+2 more episodesHarvard epidemiologist and principal investigator
- Frank E. SpeizerLead author of the 1993 paper
- C. Arden Pope III+2 more episodesEpidemiologist and co-author of the 1993 paper
- Francine LadenLed the 2006 follow-up showing cleaner air reduced mortality
- Herbert Needleman+1 more episodePediatric researcher who showed low-level lead lowered children's IQ
- Andrew Wheeler+1 more episodeEPA administrator critical of studies with inaccessible data
Where it happens
- Steubenville, Ohio+1 more episodeSix Cities site with the dirtiest air
- Watertown, MassachusettsSix Cities site with the cleanest air
- St. Louis, Missouri+2 more episodesOne of the six study cities
- Topeka, KansasOne of the six study cities
- Portage, Wisconsin+1 more episodeOne of the six study cities
- Harriman, TennesseeOne of the six study cities
Timeline
- 1970Clean Air Act enacted and EPA established
- 1974Enrollment begins in the Harvard Six Cities study
- 1979Needleman publishes his lead and IQ study
- 1987EPA shifts the particulate standard to PM10
- December 1993Six Cities paper published in the New England Journal of Medicine
- 2006Follow-up shows reducing PM2.5 reduced mortality
Still debated
The link between long-term fine-particle exposure and shorter life is among the most replicated findings in epidemiology, though debate continues over exposure estimates and biological mechanisms. The 'secret science' dispute pitted data access against participant confidentiality.
