3. Monitoring
and Evaluation
3.1 National
Pollutant Monitoring Network
3.1.1 Current
Status
The incipient nature of environmental regulation and
management in Pakistan’s industry is reflected in the lack of a proper,
comprehensive,
and effective air quality monitoring capability that can be used to track
and address specific instances of air pollution and air quality degradation.The
current air quality monitoring framework and facilities, —to
the extent that they such
as exist, —are
wholly inadequate both in
scale, technical capacity, and operational methods.They
cannotto meet
actual requirements,
given the country’s overall economic, production and population base.
At present, any systematic and technical monitoring of
air pollution in Pakistan is limited to isolated instances where the means,
resources, and corporate or political willingness are available and have
been combined to establish sound environmental management and monitoring
regimes.These cases are typically
localized to plant-
or company-wide activities.Industry,
region, or countrywide implementation of air quality monitoring practices
does not exist.
3.1.2 Existing
Capabilities
The existing capability of for air
pollution monitoring is primarily limited to three mobile air quality monitoring
stations and some other portable equipment, owned and operated by various
public sector organizations.The
mobile stations are operated by the following organizations:
aPunjab
Environmental Protection Department, Lahore
aPakistan
Council of Scientific and Industrial Research, Karachi
aPakistan
Space and Upper Atmosphere Research Commission, Karachi.
These mobile stations are generally equipped with instruments
to measure all common gaseous pollutants (nitrogen oxides, sulfur dioxide,
volatile organic compounds, carbon monoxide,
and ground-level ozone).
3.1.3 Need
for Air Quality Monitoring
Emissions of pollutants from fuel combustion and other
processes are well known. Various studies have also measured the effect
of the emissions on the ambient air quality in urban areas of Pakistan.Additionally,
a few researchers have studied the impacts of the pollutants on human health,
plants and structures.However,
data collected in this manner is not sufficient to develop a comprehensive
picture of the state of the air quality and its impacts.Therefore,
it is imperative that air quality monitoring networks be established in
selected cities of the country.Such
networks are needed for:
aEstablishing
the baseline air quality for the purpose of environmental assessments of
development projects
aDetermining
the exposure levels of citizens to harmful air pollutants
aAssessing
the potential damage to vegetation, structures,
and material from air pollutants
aDetermining
the background pollution levels for application in industrial zoning or
town planning
aValidating
and fine-tuning atmospheric dispersion models
aEvaluating
impacts of policies for mitigation and abatement of air pollution
aAssessing
transport of pollution across provincial and international boundaries.
3.1.4 Objectives
of the Air Quality Monitoring Networks
The objective of the air quality monitoring networks
will be to measure the concentration of key atmospheric pollutants—sulfur
dioxide, nitrogen oxides, ozone, carbon monoxide, inhalable particulate
matter (diameter less than 10 micron) and total suspended particulates—on
a regular basis and in a manner that:
aDaily,
seasonal and long-term changes in pollutant concentration can be tracked
aThe
average concentration of pollutants in urban areas can be established with
a reasonable level of confidence
aComparisons
can be drawn with the ambient air quality standards.
3.1.5 Location
of Proposed Monitoring Networks
Ambient air quality monitoring networks will be initially
established in six cities.Exhibit
3.1 provides some basic information on the environmental conditions
of these cities.Karachi and Lahore,beingthe
two largest cities,also have
the most industries and vehicles.After
Lahore and Karachi, Rawalpindi-Islamabad has the largest number of vehicles
in the country.Peshawar and Quetta
are located in semi-enclosed valleys that restrict dispersion of pollutants.These
cities, despite having fewer pollution sources than several other larger
cities, have reportedly the most degraded air quality in the country.
3.1.6 Location
of Sensors
While designing
a monitoring network, the location of sensors in urban areas plays a key
role in the quality of the information collected.There
are three design philosophies used for locating sensors:
aLocating
sensors on a uniform grid throughout the urban area
aLocating
sensors at locations where pollutant concentrations are expected to be
high
aLocating
sensors in proportion to the population density.
Exhibit3.1: Environmental
Conditions in Major Cities of Pakistan
|
City
|
Population ('000)
|
Setting
|
Annual Average Wind Speed
|
Estimated Number of Vehicles per 1000 Persons
|
Major Pollution Sources
|
|
Karachi
|
9,269
|
Coastal
|
2.7 m/s
|
109
|
Vehicles, Industries
|
|
Lahore
|
5,063
|
Plain
|
1.0 m/s
|
105
|
Vehicles, Industries
|
|
Faisalabad
|
1,977
|
Plain
|
1.0 m/s
|
111
|
Vehicles, Industries
|
|
Rawalpindi-Islamabad
|
1,931
|
Plateau
|
0.9 m/s
|
133
|
Vehicles, Brick kilns, waste burning
|
|
Peshawar
|
988
|
Valley
|
1.2 m/s
|
170
|
Vehicles, Industries
|
|
Quetta
|
560
|
Valley
|
1.7 m/s
|
144
|
Vehicles
|
There are inherent advantages and disadvantages in each
of these design philosophies.Exhibit
3.2 compares their
various features
of the three design philosophies.The
selection of the design depends on the purpose of the air quality monitoring
and the available resources.
Exhibit3.2: Features
of Different Designs of Monitoring Networks
|
Sensor Location
|
No. of Sensors Required
|
Type of Data Generated
|
Other Features
|
|
On a uniform grid
|
Highest
|
Average concentration of the urban area
|
Easily designed
|
|
At a high concentration point
|
Lowest
|
Maximum concentration in the urban areas
|
Useful for establishing compliance with ambient
air quality standards or otherwise
|
|
In proportion to population distribution
|
Intermediate
|
Average exposure of the urban population to the
pollutant
|
Reliable information on population distribution
is required
Localized pockets of high concentration areas may
be missed
|
At the incipient stage, the objective of the monitoring
is to track the changes in the air quality as a result of changes in the
pressure variables (number of vehicles and industry) so that a trend can
be established.This information
can be used later to monitor the effects of the air pollution abatement
measures.For this purpose,
it is suggested that the sensors be located in an area where the concentration
of the pollutants is expected to be highest and exceeds the recommended
ambient air quality standards.
Such locations can include the central business districts,
industrial zones, densely populated residential sectors,
and traffic hot spots.A few sensors
may also have to be located in relatively cleaner parts of the cities to
provide the background concentration levels.
3.1.7 Selection
of Sampling Site
Selection of the sampling site depends on the purpose
of the monitoring and the geometry of the location.When
the data is collected to determine area-wide pollutant averages, the sampler
inlet might best be located in an open area, for example,
a park or a vacant plot.On the other
hand,
if the physiological impact of the exposure is a prime consideration, the
sampler inlet should be at or near the breathing level of the people exposed.
In our case, the prime objective is to determine the
area-wide concentration of pollutants.The
identification of a representative air mass and extraction of representative
sample from the air mass poses a challenge.The
sampling site should be as close as possible to the ideal location.The
selection is complicated by the shelter effects of tall buildings, canyon
effects of streets, accessibility,
and security issues.
For selection of the sampling site, it is recommended
that:
aThe
sample should be
located in an open space within a distance of 10-15 meters from a street
intersection
aIn
general, samples should be
drawn from a standard height of 5 meters from the ground level, wherever
possible
aIf
open spaces are not available, the sensor may be
located on the roof of a two-storey building, provided it is not sheltered
by other structures.
3.1.8 Monitoring
Method
A combination of monitoring methods may be used.These
include:
aAutomated,
continuous sampling through fixed monitoring stations
aAutomated,
continuous sampling through mobile monitoring stations for a selected number
of days
aStatic
monitoring through passive samplers.
Fixed monitoring stations provide the most reliable and
extensive air quality data.These
are the hearts of the monitoring network.Site
selection for these stations requires careful attention to meteorology,
structures in the vicinity of the site, local development plans, major
pollution sources in the vicinity of the site,
and security issues.Once established,
it is difficult to move the station to another site.
Mobile stations consist of measuring instruments mounted
in air-conditioned trailers or vans.The
advantage of these stations is that they can be moved easily between locations.
Passive samplers are based on molecular diffusion of gases
through the sampler inlet.The gas
molecules are collected on an impregnated filter or an absorbent material.The
samplers are left at the sampling location for one to four weeks.After
this they are sent to qualified laboratories for analysis.
3.1.9 Proposed
Networks
Six air quality monitoring networks are proposed in six
cities of the country.The proposed
number of stations, monitoring methods, frequency, pollutants to be monitored
and the averaging times are shown in Exhibit 3.3.
Exhibit3.3: Proposed
Design of the Monitoring Networks
|
Monitoring Method and Frequency
|
Number of Stations
|
Pollutant
|
Averaging Time
|
|
|
Karachi
|
Lahore
|
Rawalpindi-Islamabad
|
Peshawar
|
Quetta
|
Faisalabad
|
|
Annual
|
24-hour
|
1-hour
|
|
Fixed,
automated station; continuous data collection
|
1
|
1
|
1
|
1
|
1
|
1
|
NOX
|
†
|
†
|
†
|
|
|
|
|
|
|
|
TSP, PM10
|
†
|
†
|
|
|
|
|
|
|
|
|
O3
|
|
†
|
†
|
|
|