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

4.2.7 Laboratory requirements
The samples collected from site are analysed in the laboratory. If possible a kiosk can be
constructed at the site and common laboratory apparatus such as refrigerator, balance, oven,
spectrophotometer etc. can be kept at the site so that the collected samples can be analysed at the
site and the losses due to improper sample preservation, transportation can be minimised.
However, enough space must be available with sufficient power at site. If constructing a kiosk at
site is not possible then the samples must be properly preserved and transported to the laboratory
for analysis. The laboratory instrument must be calibrated regularly so as to minimise errors.
4.2.8 Quality assurance
In India a nationwide network would involve large number of monitoring agencies that
would conduct monitoring at number of locations in India. The quality assurance
programme aims at achieving comparability of data from various agencies. Quality
assurance can be within laboratory quality assurance programme. Internal quality
assurance may be understood to include normal internal procedures such as periodic
calibrations, duplicate checks, split samples, spiked samples and the keeping of
adequate and neat records (WHO, 1977). External quality assurance may be taken to
include those activities that are performed on a more occasional basis, usually outside
the normal routine operations, e.g., on-site system surveys, independent performance
audits, interlaboratory comparisons, and periodic evaluation of internal quality
assurance data (WHO, 1977). The quality assurance procedures are described in detail
in the next chapter.
4.2. 9 Data Handling and Presentation
Air quality depends on the physical characteristics of the area and the site observations
must be recorded so that data interpretation can be easier. Site observations can be
type of area, whether residential, industrial, sensitive or traffic intersections, distance
from nearby sources, whether location is in a market place etc. Height of instrument
above ground level should also be recorded. The data should be validated by rejecting
erroneous data, applying corrections as per the calibrations performed of flow rates etc.
The data should be recorded on the prescribed formats. The sample of format for
recording data is shown in Annexure-III. Software programs have been developed for
doing data entry in dBase and analysis is done using FoxPro. The data presentation
should be such that the objectives of monitoring are met. One of the objective of
monitoring is to determine compliance to NAAQS so 24-hourly average and annual
average should be computed as NAAQS are given for these averages except for CO
where 8 –hourly and 1-hourly averaging should be performed. 98 th percentile should be
calculated as the NAAQS states that 24-hourly standard can be violated 2% of the times
but not on two consecutive days. One of the objectives is to understand scavenging
behaviour of environment. It is known that particulate matter is scavenged from the
environment during monsoons and in order to understand seasonal variations, monthly
averaging should be done and plotted. Best fit lines should be plotted to determine
trends in air quality.
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