Beijing car ban cut air pollutant by 40%

When officials in Beijing kept about 800,000 cars off the road for three days last year, it cut the amount of nitrogen oxide air pollution almost instantly by about 40%, Reuters reported scientists as saying on Monday.
The difference was observed from space by a NASA satellite, said Michael McElroy, a Harvard University professor of environmental studies and co-author of the report in Geophysical Research Letters.
Nitrogen oxides are key ingredients in ozone, which can exacerbate lung ailments such as asthma and emphysema.