Ambient Air quality Monitoring Guidlines. - Maharashtra Pollution ...

In regions with irregular terrain, increase the no. of stations.
In cities with extremely heavy traffic the no. of stations for NOX , Oxidants and
CO may need to be doubled.
In cities with low traffic and a population of > 4 million, the no. of station for
SO2 , NOX and CO can be reduced.
Table 4.1 (Source: WHO 1977) gives guide to the distribution of stations. These criteria
is for reference only, actual criteria followed at site must be based on compromise
between available resources and site specific parameters such as size of the city,
nature of terrain and spatial variations in the concentrations of the pollutants etc. It is
assumed in these tables that population figures are indicators of region size and
pollution variability. The number of monitoring stations are generally based on
experience gathered over the years in monitoring and can be increased or decreased
based on the analysis of data obtained in monitoring. Resource availability is also an
important factor in determining the number of monitoring stations in a city. Generally
three monitoring stations are chosen as one each in residential (or commercial),
sensitive and industrial area. Distribution of monitoring station in a city depend on the
distribution of pollution sources and population in a city. More stations should be located
in areas where population density is high, number of industries are more and vehicular
density is high. Distribution of stations can also be carried out by dividing the entire area
in a grid and locating stations at intersections of a grid or within a grid. However, the
grid pattern is not very economical as most often it requires large number of stations in
a city. Dispersion models can be used to find maximum pollution levels and spatial
variation of pollutant concentration can be used to determine distribution of stations.
Table: 4.2 Distribution of Sampling Stations (Source: WHO, 1977)
Total number of stations
1
2
3
4
5
10
4.2.3 Selection of Monitoring Location
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Number of stations
In city centre or
industrial areas
1
1
2
2
3
6
In residential areas
Principal factors governing the locations of the sampling stations are the objectives, the
particular method of instrument used for sampling, resources available, physical access and
security against loss and tampering. Air quality monitoring should be done in areas where
pollution problem exists or is expected i.e. mainly in industrial areas, urban areas, traffic
intersections etc. One of the objective of monitoring is to determine status and trends and the air
quality monitoring should be done in metropolitan cities and other urban areas so as to compare
0
1
1
2
2
4