Page 479 - Air pollution and greenhouse gases from basic concepts to engineering applications for air emission control

460 15 Air Monitoring

15.6 Ambient Air Quality Monitoring

Ambient air quality monitoring data is used to determine local air quality index
and the levels of air pollution in the region, to establish and evaluate air pollu-
tion control measures, and to evaluate air dispersion models or some of their
parameters. Sometimes it is also used to warn the citizens when the air pollution is
hazardous.
Ambient air quality monitoring network in most regions employs continuous
monitoring of outdoor air quality. These networks measure the amount of gaseous
air pollutants and particulate matter at multiple locations to produce statistically
correct data.
Like air emission monitoring systems, there are two types of ambient air quality
monitoring systems: integrated and continuous monitoring systems. In integrated
monitoring, samples are collected using standard devices over a certain time
interval. The samples collected are analyzed in a laboratory.
A continuous air quality monitoring system constitutes both air sampling and
pollutant characterization devices in one system. Samples are taken and analyzed
continuously. Air pollutant concentrations are nearly instantaneously displayed or
continuously recorded by a data logging mechanism. The system can also be
programmed to take samples and display results over certain interval, say every
10 min or 2 h. The intervals set by the operator should follow the guideline set in
the corresponding air quality standards. The data can also be sent to a central
location for further analysis via wired or wireless network. On the other hand, this
type of system requires sophisticated instruments and well-trained professionals to
operate and to maintain the system.
An air quality monitoring network can also be mobile. Mobile air quality
monitoring networks are set in trailers, automobiles, or other mobile units. They
take samples and display data on schedule among selected locations. Consequently,
data are collected in time sequence. The mobile air quality monitoring and sampling
features its flexibility in air quality measurements and it provides a much higher
resolution in the geographical variations if the air monitoring practice lasts long
enough to generate meaningful data.

References and Further Readings

1. Belyaev S, Levin L (1974) Techniques for collection of representative aerosol samples. Aerosol
Sci 5:325–338
2. Bowers K (1998) Continuous emission monitors compliance assistance program. Air Resources
Board, California Environmental Protection Agency, p 95
3. Du K, Rood MJ, Kim B, Kemme M, Franek B, Mattison K (2007) Quantification of plume
opacity by digital photography. Environ Sci Technol 41:928–935
4. Du K, Shi P, Rood M, Wang K, Wang Y, Varma R (2013) Digital optical method to quantify
the visual opacity of fugitive plumes. Atmos Environ 77:983–989