Meningitis is a disease caused by the inflammation of the protective membranes covering the brain and the spinal cord. While most people with meningitis recover, it can cause serious complications, such as brain damage, hearing loss or learning disabilities. A vaccination is the most effective way to protect yourself against certain types of meningitis.
Primary & Secondary pollutant. Definition: A primary pollutant is an air pollutant emitted directly from a source. A secondary pollutant is not directly emitted as such, but forms when other pollutants (primary pollutants) react in the atmosphere.
1 Continental air masses are characterized by dry air near the surface while maritime air masses are moist. 2  Polar air masses are characterized by cold air near the surface while tropical air masses are warm or hot.3  Arctic air masses are extremely cold. Five air masses affect the United States during the course of a typical year: continental polar, continental arctic, continental tropical, maritime polar, and maritime tropical. 2  Continental air masses are characterized by dry air near the surface while maritime air masses are moist.