Navigation at Sea, History of. The first Western civilization known to have developed the art of navigation at sea were the Phoenicians, about 4,000 years ago (c. 2000 B.C.E. ). Phoenician sailors accomplished navigation by using primitive charts and observations of the Sun and stars to determine directions.
Air pollution risk is a function of the hazard of the pollutant and the exposure to that pollutant. Air pollution exposure can be expressed for an individual, for certain groups (e.g. neighborhoods or children living in a county), or for entire populations.ther examples include carbon monoxide gas from motor vehicle exhaust, or the sulfur dioxide released from factories. Secondary pollutants are not emitted directly. Rather, they form in the air when primary pollutants react or interact.
GASES OF THE AIR. The air around us is a mixture of gases, mainly nitrogen and oxygen, but containing much smaller. amounts of water vapor, argon, and carbon dioxide, and very small amounts of other gases. Air also contains. suspended dust, spores, and bacteria.