Questions of type 8 can direct monitoring to
the areas where there is likely to be air pollution
by developing an understanding of which practices are likely to create the most pollution and
which are relatively benign, requiring less monitoring. Questions of type 9 bring about understanding of how changes in practice impact air
pollution concentrations and whether current policies are effective. Type 10 questions can lead to
development of new technologies and strategies
for monitoring, as well as improvements to
existing techniques.
Current Air Pollution Monitoring
Practices
Common pollutants (Criteria pollutants, CACs)
are routinely monitored in the USA, Canada,
Europe, throughout Asia, and elsewhere. Networks of in situ monitoring stations in these
regions provide constant measures of air quality
and help governments and concerned organizations determine how close they are to meeting
their air quality goals. Precipitation chemistry
monitoring also provides data on pollutants in
air. Satellite remote sensing and air quality models
complement the data collected by monitoring stations to form a more complete picture of air quality and can offer the advantage of consistent
methods across the globe. Stack emissions for
point sources are occasionally monitored in
some countries to complement the ambient concentration data collected by monitoring networks,
though more often large emitters estimate their
emissions using mass-based flow balances for
their site and rates of activity. Numerical modeling of air pollution can be a stand-in when measured data are sparse, it can be used in conjunction
with other forms of monitoring, and can help
predict the effects of changes in emissions patterns. Craig et al. [14] list the outcomes of monitoring air pollution as follows:
• Ability to describe risks and detect potential
future risks.
• Documentation of trends, which can demonstrate the impacts of policies.
• Inputs for the further development of models
which can improve predictive capacity.
• Information necessary to prove links between
pollution concentrations and effects.
Typical observations made during monitoring
include concentrations in ambient air (in ppm, mg/m
3
,
particles/m
3 , mol/L, etc.), rates of emission, typical concentration ranges, rates of change of concentration, and concentration profiles. It is in
terms of ambient concentration that pollution
standards are set. For example, the European standard for ozone is set such that the maximum
concentration of ozone averaged over any 8 h
period of the day should not exceed 120 mg/m
3 .
Thus, it can be seen that monitoring is important
to ensuring that air quality standards are adhered
to, and that public health and the environment are
protected.
In Situ Monitoring
Air quality monitoring stations exist in the hundreds in some countries and in the thousands
globally, covering continental areas and forming
networks that contribute the bulk of information
to assessments of outdoor air quality. Instruments
capable of detecting specific pollutants (NO x ,
SO x , PM 2.5 , etc.) draw in ambient air and accurately measure the pollutant mass per standard
volume of air. This type of monitoring, referred
to as in situ monitoring, results in the least uncertainty as compared to satellite remote sensing and
model estimates. It is important to recognize that
the in situ data from a given monitoring location
are only for the specific geographic location and,
thus, during the process of site selection, the issue
of spatial representativeness must be considered
in the context of monitoring objectives.
Most existing stations measure near ground
level (~3–10 m) so that air pollution at the exposure height of the general populace can be quantified. Figure 1 shows the location of ozone
monitoring stations throughout North America.
It is largely through such networks of stations
that an area’s compliance with current air quality
standards is determined. Networks are also a primary tool in the tracking of progress toward air
398
Air Pollution Monitoring and Sustainability
the areas where there is likely to be air pollution
by developing an understanding of which practices are likely to create the most pollution and
which are relatively benign, requiring less monitoring. Questions of type 9 bring about understanding of how changes in practice impact air
pollution concentrations and whether current policies are effective. Type 10 questions can lead to
development of new technologies and strategies
for monitoring, as well as improvements to
existing techniques.
Current Air Pollution Monitoring
Practices
Common pollutants (Criteria pollutants, CACs)
are routinely monitored in the USA, Canada,
Europe, throughout Asia, and elsewhere. Networks of in situ monitoring stations in these
regions provide constant measures of air quality
and help governments and concerned organizations determine how close they are to meeting
their air quality goals. Precipitation chemistry
monitoring also provides data on pollutants in
air. Satellite remote sensing and air quality models
complement the data collected by monitoring stations to form a more complete picture of air quality and can offer the advantage of consistent
methods across the globe. Stack emissions for
point sources are occasionally monitored in
some countries to complement the ambient concentration data collected by monitoring networks,
though more often large emitters estimate their
emissions using mass-based flow balances for
their site and rates of activity. Numerical modeling of air pollution can be a stand-in when measured data are sparse, it can be used in conjunction
with other forms of monitoring, and can help
predict the effects of changes in emissions patterns. Craig et al. [14] list the outcomes of monitoring air pollution as follows:
• Ability to describe risks and detect potential
future risks.
• Documentation of trends, which can demonstrate the impacts of policies.
• Inputs for the further development of models
which can improve predictive capacity.
• Information necessary to prove links between
pollution concentrations and effects.
Typical observations made during monitoring
include concentrations in ambient air (in ppm, mg/m
3
,
particles/m
3 , mol/L, etc.), rates of emission, typical concentration ranges, rates of change of concentration, and concentration profiles. It is in
terms of ambient concentration that pollution
standards are set. For example, the European standard for ozone is set such that the maximum
concentration of ozone averaged over any 8 h
period of the day should not exceed 120 mg/m
3 .
Thus, it can be seen that monitoring is important
to ensuring that air quality standards are adhered
to, and that public health and the environment are
protected.
In Situ Monitoring
Air quality monitoring stations exist in the hundreds in some countries and in the thousands
globally, covering continental areas and forming
networks that contribute the bulk of information
to assessments of outdoor air quality. Instruments
capable of detecting specific pollutants (NO x ,
SO x , PM 2.5 , etc.) draw in ambient air and accurately measure the pollutant mass per standard
volume of air. This type of monitoring, referred
to as in situ monitoring, results in the least uncertainty as compared to satellite remote sensing and
model estimates. It is important to recognize that
the in situ data from a given monitoring location
are only for the specific geographic location and,
thus, during the process of site selection, the issue
of spatial representativeness must be considered
in the context of monitoring objectives.
Most existing stations measure near ground
level (~3–10 m) so that air pollution at the exposure height of the general populace can be quantified. Figure 1 shows the location of ozone
monitoring stations throughout North America.
It is largely through such networks of stations
that an area’s compliance with current air quality
standards is determined. Networks are also a primary tool in the tracking of progress toward air
398
Air Pollution Monitoring and Sustainability