Introduction to Ambient Air Pollution
Air pollution can be classified as a chemical, particulate matter, or biological agent that modifies the natural characteristics of the atmosphere. The atmosphere is a complex, dynamic natural gaseous system that is essential to support life on planet Earth. Ambient air pollution has long been recognized as a threat to human health as well as to the Earth's ecosystems.
Ice fog over Fairbanks, Alaska in winter 2005. Temperature approximately minus 30F. Joseph N. Hall
There are many substances in the air which may impair the health of plants and animals (including humans), or reduce visibility. These arise both from natural processes and human activity. Substances not naturally found in the air or at greater concentrations or in different locations from usual are referred to as pollutants.
Pollutants can be classified as either primary or secondary. Usually, primary pollutants are substances directly emitted from a process, such as ash from a volcanic eruption, the carbon monoxide gas from a motor vehicle exhaust or sulfur doixide released from factories.
Secondary pollutants are not emitted directly. Rather, they form in the air when primary pollutants react or interact. An important example of a secondary pollutant is ground level ozone - one of the many secondary pollutants that make up photochemical smog.
Some pollutants may be both primary and secondary: that is, they are both emitted directly and formed from other primary pollutants. Major primary pollutants produced by human activity include:
Secondary pollutants include:
Worldwide air pollution is responsible for large numbers of deaths and cases of respiratory disease. While major stationary sources are often identified with air pollution, the greatest source of emissions is actually mobile sources, mainly automobiles.
There are several sources of ambient or outdoor air pollution which will be discussed further. Some of these sources are:
Some environmental issues from ambient air pollution are the greenhouse effect and ocean acidification The greenhouse effect is a phenomenon whereby greenhouse gases create a condition in the upper atmosphere causing a trapping of heat and leading to increased surface and lower tropospheric temperatures. Greenhouse gases include methane, hydrofluorocarbons, perfluorocarbons, chlorofluorocarbons, NOx, and ozone. Many greenhouse gases, contain carbon, and some of that from fossil fuels.
Ocean acidification is the name given to the ongoing decrease in the pH of the Earth's oceans, caused by their uptake of anthropogenic carbon dioxide from the atmosphere. Between 1751 and 1994 surface ocean pH is estimated to have decreased from approximately 8.179 to 8.104 (a change of -0.075).
http://www.pacificscience.org/tfoceanacidification.html.
While the full ecological consequences of these changes in calcification are still uncertain, it appears likely that many calcifying species will be adversely affected. There is also a suggestion that a decline in the coccolithophores (single cell algae and phytoplankton) may have secondary effects on climate change, by decreasing the earth's albedo via their effects on oceanic cloud cover.
Aside from calcification, organisms may suffer other adverse effects, either directly as reproductive or physiological effects (e.g. CO2-induced acidification of body fluids, known as hypercapnia), or indirectly through negative impacts on food resources. However, as with calcification, as yet there is not a full understanding of these processes in marine organisms or ecosystems. http://www.tasmedia.org/node/1214.
Another document Impacts of ocean acidification on Coral Reefs and other Marine Calcifiers can be found at: http://www.ucar.edu/communications/Final_acidification.pdf.
When I was in school I hated science. I couldn't understand it. Not only was it in another language [English], but all the examples were foreign. If we begin to speak of 'Yup'ik science,' we will give our children something they can understand. --Agatha John-Shields, Bethel, March 2004