Inside the Fight for Cleaner Air.

The author reflects on a global fight for cleaner air as of 2016, and it mentions the air pollution in places such as London, England, New Dehli, India, and Beijing, China, as well as the World Health Organization's estimate that nine out of 10 people live in areas with excessive air pollution. The health issues that are associated with exposure to air pollutants are examined, including asthma, lung disease, and death. Emissions-reduction programs in the U.S. and Mexico are assessed.