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.
The gases in the atmosphere that absorb radiation are known as greenhouse gases (sometimes abbreviated as GHG) because they are largely responsible for the greenhouse effect. The greenhouse effect, in turn, is one of the leading causes of global warming. The most significant greenhouse gases are water vapor (H 2 O), carbon dioxide (CO 2), methane (CH 4) and nitrous oxide (N 2 O), according to the Environmental Protection Agency (EPA).