regarding limits in gasoline, and emissions from
coal-fired power plants, as well as other industrial
control, are in most cases effective in mitigating
their emissions. Thus, developing nations generally have higher levels in general than industrialized nations.
Conclusions
Urban air quality is subjectively determined based
on levels or concentrations measured, monitored,
and mandated generally by law. Urban air quality
is the resulting state of a function of a complex
and dynamic mixture of gaseous and particulate
pollutants emitted from natural and human environments and their interaction with the natural and
built environment. The concentration of pollutants both produced in photochemical reactions
and suspended in the air of the urban environment
and therefore air quality is weather dependent and
thus exhibits daily and seasonal variation due to
both anthropogenic and biologic activity levels
and weather conditions.
The actual pollution load in a given urban area
is the result of both local conditions and emissions
and transport from nearby and remote sources.
The location of the city is very important for the
local dispersion conditions, which are governed
by meteorology but are also heavily affected by
natural topographical conditions (e.g., effects of
coastline, mountains, valleys, etc.).
Studies of the impact of transportation hubs
such as local harbors and airports on urban air
quality have generally pointed at a limited influence, with the impact on the air quality mainly
related to the road traffic that these facilities are
generating.
The highest urban air pollutant concentrations
of the pollutants PM10 and SO2 are generally
found in developing urban environments such as
those in Africa, Asia, and Latin America.
The highest levels of photochemical pollutants
such as O 3 and NO 2 are observed in Latin America and certain developed countries – topographical conditions and weather conditions are very
important factors in this respect.
The negative health effects of urban air pollution are well documented and are found to be
particularly severe in the megacities, where quality of life is lessened due to air pollution. The
interaction of poor air quality with other lifestyle
decisions such as smoking generally results in a
synergistic effect. The negative health effects of
poor ambient air quality are likely enhanced by
exposure to tobacco smoke, indoor particulate,
and gaseous sources from cooking, candles,
stoves, etc. but also by exposures to the nonairborne agents in textiles, food, etc. The possibility of reduced productivity from toxics and their
associated costs should be investigated, and valuation models should be further developed [5].
Even though the health effects of poor urban air
quality have been documented in numerous studies, there are still many unknowns, and through
their investigation, there is a possibility for improving health, environment, and the climate. The
reader is referred to Hertel and Goodsite, 2009
[65] – from which this entry was based and
updated, as well as the supplemental literature list
where we have included recent reviews across
various aspects of the field of urban air quality.
Future Directions
Given the progress documented through 25 specific
solutions in “Air pollution measures for Asia and the
Pacific 25 science-based solutions to bring clean,
safe air to 1 billion people” http://www.ccacoalition.
org/en/content/air-pollution-measures-asia-and-paci
fic, it is important to follow the recommendations
made in the report. Investigating to what extent
deploying the solutions will continue to improve
urban air quality and in which context, in the studied
regions and other urban regions, given increasing
urbanization, is needed as soon as feasible. The
general understanding of urban air quality within
the broader political, economic, social technological, environmental, and security (PESTLES) framework needs to be developed. Ye et al. [66]
documented that there are cultural aspects that
must be taken into consideration. The understanding
of culture and communications toward changing
practice is important to continue to understand effective deployment of mitigative measures and political
or technological solutions in urban areas.
Urban Air Quality: Sources and Concentrations
211
coal-fired power plants, as well as other industrial
control, are in most cases effective in mitigating
their emissions. Thus, developing nations generally have higher levels in general than industrialized nations.
Conclusions
Urban air quality is subjectively determined based
on levels or concentrations measured, monitored,
and mandated generally by law. Urban air quality
is the resulting state of a function of a complex
and dynamic mixture of gaseous and particulate
pollutants emitted from natural and human environments and their interaction with the natural and
built environment. The concentration of pollutants both produced in photochemical reactions
and suspended in the air of the urban environment
and therefore air quality is weather dependent and
thus exhibits daily and seasonal variation due to
both anthropogenic and biologic activity levels
and weather conditions.
The actual pollution load in a given urban area
is the result of both local conditions and emissions
and transport from nearby and remote sources.
The location of the city is very important for the
local dispersion conditions, which are governed
by meteorology but are also heavily affected by
natural topographical conditions (e.g., effects of
coastline, mountains, valleys, etc.).
Studies of the impact of transportation hubs
such as local harbors and airports on urban air
quality have generally pointed at a limited influence, with the impact on the air quality mainly
related to the road traffic that these facilities are
generating.
The highest urban air pollutant concentrations
of the pollutants PM10 and SO2 are generally
found in developing urban environments such as
those in Africa, Asia, and Latin America.
The highest levels of photochemical pollutants
such as O 3 and NO 2 are observed in Latin America and certain developed countries – topographical conditions and weather conditions are very
important factors in this respect.
The negative health effects of urban air pollution are well documented and are found to be
particularly severe in the megacities, where quality of life is lessened due to air pollution. The
interaction of poor air quality with other lifestyle
decisions such as smoking generally results in a
synergistic effect. The negative health effects of
poor ambient air quality are likely enhanced by
exposure to tobacco smoke, indoor particulate,
and gaseous sources from cooking, candles,
stoves, etc. but also by exposures to the nonairborne agents in textiles, food, etc. The possibility of reduced productivity from toxics and their
associated costs should be investigated, and valuation models should be further developed [5].
Even though the health effects of poor urban air
quality have been documented in numerous studies, there are still many unknowns, and through
their investigation, there is a possibility for improving health, environment, and the climate. The
reader is referred to Hertel and Goodsite, 2009
[65] – from which this entry was based and
updated, as well as the supplemental literature list
where we have included recent reviews across
various aspects of the field of urban air quality.
Future Directions
Given the progress documented through 25 specific
solutions in “Air pollution measures for Asia and the
Pacific 25 science-based solutions to bring clean,
safe air to 1 billion people” http://www.ccacoalition.
org/en/content/air-pollution-measures-asia-and-paci
fic, it is important to follow the recommendations
made in the report. Investigating to what extent
deploying the solutions will continue to improve
urban air quality and in which context, in the studied
regions and other urban regions, given increasing
urbanization, is needed as soon as feasible. The
general understanding of urban air quality within
the broader political, economic, social technological, environmental, and security (PESTLES) framework needs to be developed. Ye et al. [66]
documented that there are cultural aspects that
must be taken into consideration. The understanding
of culture and communications toward changing
practice is important to continue to understand effective deployment of mitigative measures and political
or technological solutions in urban areas.
Urban Air Quality: Sources and Concentrations
211