A cheap coating applied to roofs can make big difference for the environment. How much smog can it eat? Each year it could “remove the same amount of nitrogen oxides as a car emits when driving 11,000 miles.” Other chemical solutions do exist but they are not this inexpensive.
The titanium dioxide in the coating strips the harmful elements from the smog and rain will wash the harmless remains away. If this coating is applied to a million roofs, 21 tons of nitrogen oxides would be eaten each day. To learn more, see Co.Exist’s article, Delicious: With A $5 Investment, Your Roof Could Start Eating Smog.