US Patents for anything are good for 17 years.
In the last 30 years air quality has generally improved. Amount of most major air pollutants have decreased. Many newer cars cause less pollution.
After 25 years on the air, Oprah's last original show will air May 25, 2011. Many wonder who her final guest(s) will be and as of lately it has not been announced.
When well-maintained it can last for ten years.
His first credited movie was "Love is on the Air" (1937), and his last was "The Killers"(1964), so that would span 27 years
Yes, if you have a new and non-obvious chemical or mechanical way to improve the art, you may be entitled to a patent.
Provided it is stored out of sunlight in an air tight container sugar will last for years.
10 years
A well maintained one can last for several years. I know lots of people who drive trucks which were manufactured in the 1980s... they may have replaced motors and added air ride suspensions, but the basic truck is still the same as what they bought over 20 years ago.
The first successful automobile air bag patent is held by Allen Breed.
4 years.
42 years
Restrictions on CFC's.