Air pollution is the presence
of
undesirable material in air, in quantities large enough to produce harmful effects. This definition does no trestrict air pollution to hlman causes, although we normally only talk about these. The undesirable materials may damage human health,vegetation,human property,
or
theglobal environmentaswell
as
create aestheticinsultsintheform
of
brown
or
hazyair
or
unpleasantsmells.Pollutants are knownthat maydo all
of
thesethings.Many
of
theseharmfulmaterialsentertheatmosphere from sources currentlybeyond humancontrol. However, in themost densely inhabitedparts
of
theglobe,particularlyintheindustrialized countries,theprincipal sources
of
these pollutantsarehumanactivities. These activities areclosely associated with ourmaterialstandard
of
living.
To
eliminate
theseactivitieswould cause such adrastic decreaseinthestandard
of
living thatthisaction isseldom considered.The remedy proposedinmostindustrial countries is to continuetheactivities and controltheair pollutant emissions fromthem.
1.1 SOME OF THE HISTORY OF AIR POLLUTION CONTROLIN
·
THE UNITED STATES OF AMERICA
Althoughair pollutioncontrol actions gobackatleastasfar
as
thethirteenth century
[1],*
most
of
the majoreffort in the worldhastakenplacesince1945.Beforethen,othermatterswerehigher onsociety'sprioritylist (and are stillhigher indeveloping