in biomass burning and coal (heating) with a 19%
difference in the total concentrations observed
between fall (63%) and winter (82%). The sources
showed an inverse profile when moving away
from the city. The study authors used source analysis to attribute this to the long-range transport of
atmospheric pollutant (LRTAP) of PAHs and their
precursors from sources in China or North Korea
thus demonstrating that for certain urban environments, in footprints of major industrial areas,
PAHs from local and long-range transport must
be taken into greater consideration as air quality
management plans are updated.
Trace Elements to Include Heavy Metals
in Urban Areas
Trace elements including heavy metals (HM) are
ubiquitous in the atmosphere of urban areas, and
many are classified by authorities as hazardous air
pollutants (HAP).
These represent serious environmental and
health risks and are especially of concern in urban
and industrial climates, with megacities in developing nations being the obvious sites of concern
for populations at risk for trace element exposure.
Air quality can be affected and trends in urban
areas have been noted. One study has provided
trends and levels of trace metals in three Danish
cities as well as at background sites [61]. The
levels reported are less than literature values for
megacities, as expected, but in many cases, the
trends are similar, though the numbers of studies
are very limited.
Heavy Metals in the Urban Atmosphere
Heavy metals are still a problem for ambient and
indoor air quality, especially in general in urban
and industrial areas despite that many nations have
tightened and continue to restrict emissions of such
trace elements as mercury. Even with history of
progressive regulation of trace metals, they still
represent a real and pressing health and environmental hazard in the USA (US EPA 2006) and
most certainly in other western nations and other
countries as well. Trace metals have been measured
in nearly all aerosol size fractions, so it is of paramount importance to characterize the particle size
distribution and relate these to the potential adverse
health effects in the urban population [62].
Humans are exposed to metals via ambient air
inhalation and consuming contaminated food or
water, as well as, in the case of lead and children,
chewing on lead painted toys and exposure from
walls or furniture. Metals were of great concern in
western cities prior to lead being banned as an
anti-knock agent in gasoline in the mid-1970s, as
well as other regulations regarding the use of lead
in, for example, house paints.
The US Environmental Protection Agency
(US EPA) lists many trace metals as among the
worst urban air toxics (www.epa.gov/ttn/atw/nata/
34poll.html, November 28, 2008), and several
metals aside from mercury and lead are classified
by the US Clean Air Act as HAPs: chromium,
manganese, nickel, and cadmium. There is no
reason that other countries should not also endorse
this classification in their air quality plans.
Trace Elements in the Urban Atmosphere
Trace elements (and metals) and the observed
high levels of them in the urban environment
have led to extensive monitoring with consequential regulations and international agreements that
have greatly reduced the concentrations.
The sources of emission into the urban atmosphere of commonly measured trace elements, Be,
Co, Hg, Mo, Ni, Sb, Se, Sn, and V, with smaller
concentrations of As, Cr, Cu, Mn, and Zn, are
primarily human activities, especially the combustion of fossil fuels and biomass, industrial
processes, and waste incineration [62].
As with PAHs, there are seasonal variations of
trace metals in PM 10 and PM 2.5 observed in campaigns conducted seasonally. Higher winter values
of nearly all trace elements are observed suggesting
a significant source of particles from domestic
heating in most temperate urban areas and/or less
efficient dispersion of emissions in winter.
Many trace elements are primarily observed
from natural sources and have local, regional, and
global effects. Sources include sea spray near coastlines, dust from aeolian processes and weathering
(especially noted in Asia), and volcanoes.
The main source of trace elements in most urban
environments is never the less, anthropogenic
activities, and national regulations, especially
210
Urban Air Quality: Sources and Concentrations
difference in the total concentrations observed
between fall (63%) and winter (82%). The sources
showed an inverse profile when moving away
from the city. The study authors used source analysis to attribute this to the long-range transport of
atmospheric pollutant (LRTAP) of PAHs and their
precursors from sources in China or North Korea
thus demonstrating that for certain urban environments, in footprints of major industrial areas,
PAHs from local and long-range transport must
be taken into greater consideration as air quality
management plans are updated.
Trace Elements to Include Heavy Metals
in Urban Areas
Trace elements including heavy metals (HM) are
ubiquitous in the atmosphere of urban areas, and
many are classified by authorities as hazardous air
pollutants (HAP).
These represent serious environmental and
health risks and are especially of concern in urban
and industrial climates, with megacities in developing nations being the obvious sites of concern
for populations at risk for trace element exposure.
Air quality can be affected and trends in urban
areas have been noted. One study has provided
trends and levels of trace metals in three Danish
cities as well as at background sites [61]. The
levels reported are less than literature values for
megacities, as expected, but in many cases, the
trends are similar, though the numbers of studies
are very limited.
Heavy Metals in the Urban Atmosphere
Heavy metals are still a problem for ambient and
indoor air quality, especially in general in urban
and industrial areas despite that many nations have
tightened and continue to restrict emissions of such
trace elements as mercury. Even with history of
progressive regulation of trace metals, they still
represent a real and pressing health and environmental hazard in the USA (US EPA 2006) and
most certainly in other western nations and other
countries as well. Trace metals have been measured
in nearly all aerosol size fractions, so it is of paramount importance to characterize the particle size
distribution and relate these to the potential adverse
health effects in the urban population [62].
Humans are exposed to metals via ambient air
inhalation and consuming contaminated food or
water, as well as, in the case of lead and children,
chewing on lead painted toys and exposure from
walls or furniture. Metals were of great concern in
western cities prior to lead being banned as an
anti-knock agent in gasoline in the mid-1970s, as
well as other regulations regarding the use of lead
in, for example, house paints.
The US Environmental Protection Agency
(US EPA) lists many trace metals as among the
worst urban air toxics (www.epa.gov/ttn/atw/nata/
34poll.html, November 28, 2008), and several
metals aside from mercury and lead are classified
by the US Clean Air Act as HAPs: chromium,
manganese, nickel, and cadmium. There is no
reason that other countries should not also endorse
this classification in their air quality plans.
Trace Elements in the Urban Atmosphere
Trace elements (and metals) and the observed
high levels of them in the urban environment
have led to extensive monitoring with consequential regulations and international agreements that
have greatly reduced the concentrations.
The sources of emission into the urban atmosphere of commonly measured trace elements, Be,
Co, Hg, Mo, Ni, Sb, Se, Sn, and V, with smaller
concentrations of As, Cr, Cu, Mn, and Zn, are
primarily human activities, especially the combustion of fossil fuels and biomass, industrial
processes, and waste incineration [62].
As with PAHs, there are seasonal variations of
trace metals in PM 10 and PM 2.5 observed in campaigns conducted seasonally. Higher winter values
of nearly all trace elements are observed suggesting
a significant source of particles from domestic
heating in most temperate urban areas and/or less
efficient dispersion of emissions in winter.
Many trace elements are primarily observed
from natural sources and have local, regional, and
global effects. Sources include sea spray near coastlines, dust from aeolian processes and weathering
(especially noted in Asia), and volcanoes.
The main source of trace elements in most urban
environments is never the less, anthropogenic
activities, and national regulations, especially
210
Urban Air Quality: Sources and Concentrations