Environmental Engineering Reference
In-Depth Information
What is urban air pollution?
Urban air pollution is probably the most visible undesirable product of civilization.
It was an issue even in the 16th century, when British Parliament sessions in Lon-
don had to be postponed due to the severe pollution “episodes” resulting from the
use of fuel wood and coal for residential heating. The soot and particulates emit-
ted act as cluster for water vapor in the atmosphere, creating thick fog. One of the
most serious incidences occurred in 1952, when very heavy fog in London res-
ulted in 4,000 deaths and more than 20,000 cases of illness. The pollution of the
Thames River was a significant contributor. Such disasters led to passage of the
UK Clean Air Act of 1956, establishing limits on the emission of pollutants and
acceptable levels of air quality. Other legislation followed in the United Kingdom,
North America, many other western European countries, and Japan. As a result,
monitoring, regulatory, and assessment agencies on environmental quality were set
up, with highly beneficial consequences.
The five main urban air pollutants are:
- Sulfur oxides (SO x , mainly SO 2 );
- Nitrogen oxides (NO x and mainly nitric oxide (NO) and nitrogen dioxide (NO 2 );
- Carbon monoxide (CO);
- Particulate matter—PM (including heavy metals such as lead); and
- Ozone (O 3 ).
Energy systems are the main source of sulfur dioxide emissions (constituting 90%
of total emissions). Emissions of SO 2 , which combine with water vapor in the at-
mosphere to produce sulfuric acid rain, have decreased in developed regions over
the past two decades, while those in developing regions have increased.
In industrialized regions, industry and transportation are the main sources of
CO 2 emissions. Combustion of fossil fuels and the burning of wood as fuel con-
tribute to about one-third of total human made emissions. In developing regions
inefficient combustion in primitive stoves, furnaces, and boilers is a main source.
What is indoor air pollution?
There are three types of problems related to indoor air pollution:
- Traditional—due to cooking, generally indoors, which produces smoke, particulates,
carbon monoxide, and other gases mainly affecting the rural poor. More than 1 billion
people in developing countries are victims of this type of pollution.
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