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.
But, the water that makes the air humid isn't liquid. It's water vapor, which is a gas that is lighter than nitrogen or oxygen. (Related: Understanding water in the atmosphere). Compared to the differences made by temperature and air pressure, humidity has a small effect on the air's density. But, humid air is lighter than dry air at the same temperature and pressure.