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.
Air pollution is the pollution of air by smoke and harmful gases, mainly oxides of carbon, sulfur, and nitrogen. Many of the world's large cities today have bad air quality. Even 2,000 years ago, the Romans were complaining about the bad air in their cities. At that time, the air was thick with smoke from fires and the smell of sewers.