From documentary website:

Can air pollution cause long-lasting effects on children’s respiratory health? In 1992, the California Air Resources Board funded a study to try to answer questions on the long-term health effects of air pollution on children. The video describes the results of the Children’s Health Study, which was conducted by a team of scientists at the University of Southern California. Scientists looked at 5,500 children from 12 communities in Southern California with differing types and levels of air pollution. The scientists followed children from each of these communities and then compared their respiratory health with the pollution levels in their communities.

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