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.
1 Ozone is a naturally occurring gas found in the troposphere and other parts of the atmosphere. 2  Tropospheric ozone is often called bad ozone because it can damage living tissue and break down certain materials. Tropospheric ozone is often called bad ozone because it can damage living tissue and break down certain materials. 2  Concentrations of ozone are not uniform in the troposphere. 3  Longer exposure to ozone will increase the negative effects.