On hazy days, visitors to Yosemite National Park in California contend with obscured views because of pollutants released hundreds and even thousands of miles away.
Little things mean a lot, especially when it comes to air pollution.
According to new research, pollutants that are less than one-fifth the width of a strand of hair can deal death blows to residents of big cities and obscure views for thousands of miles. The study, which looked at the national effects of air pollution, found that as levels of particulates less than 2.5 micrograms increased in the air, so did the death toll. It s pretty sweeping, says study author Jonathan Samet of Johns Hopkins' Department of Epidemiology. He explains that fine particulate pollution, or microscopic bits of soot and liquid, comes from just about everywhere, including cars, trucks, tires, electric plants, fireplaces and even backyard barbecues. Efforts to regulate and control the myriad sources of fine particulate pollution could cost tens of billions of dollars.