There are four main types of air pollution sources: mobile sources â such as cars, buses, planes, trucks, and trains stationary sources â such as power plants, oil refineries, industrial facilities, and factories
Incubation Period: Average 9-10 days. Period of Communicability: Highly communicable in the early phase and at the beginning of the paroxysmal cough stage (first 2 weeks). The child is no longer contagious after 5 days of treatment.
A person is not contagious during the incubation period. A person is mildly contagious when he or she first experiences symptoms. A person is most contagious about 4 days before the onset of the measles rash. Some risk of transmission lasts until about 4 days after the rash starts.