1.1 NATIONAL MONITORING NETWORK

After the Air quality monitoring began in India in the late 1960s’ planners focused only on a few pollutants namely sulphur dioxide, nitrogen oxides and suspended particulate matter. Other pollutants such as carbon monoxide and lead were monitored only on a limited scale. Threat from other air pollutants such as benzene, polynuclear aromatic hydrocarbons (PAHs), ozone and respirable particulate matter is not much known as comprehensive and systematic monitoring of these pollutants has not yet begun in India.

Air quality monitoring network needs to be established in urban areas where air pollution is an actual or potential problem. Monitoring is essential for assessing the effectiveness of air pollution control programme. The goal of air quality information system is through monitoring to keep authorities, major polluters and the public informed about the short and long term changes in air quality, thereby, helping to raise the awareness and to assess the results of abatement measures thus providing feedback to the abatement strategy. The choice of pollutants to be used as indicator of the air quality situation depends upon the composition and extent of sources in the city. Experience with air quality assessment in the Indian cities indicate that in general sulphur dioxide (SO₂), oxides of nitrogen (NO_x), ozone (O₃) and particulate matter (PM) are the major urban pollutants. Other pollutants requiring increasing attention are carbon monoxide and benzene.

Monitoring Ambient Air

Central Pollution Control Board initiated its own National Ambient Air Quality Monitoring (NAAQM) Programme in 1984. The programme started with a few stations in Agra and Annapada in the State of Uttar Pradesh. Subsequently more stations were added. Over the years, the number of stations have increased and presently the network comprises 290 stations spread over 92 cities/towns distributed over 24 states and 4 Union Territories (Table - 1). In addition to the NAAQM programme, operated by CPCB, many State Boards have set up ambient air quality monitoring stations under their own programme known as State Ambient Air Quality Monitoring (SAAQM) programme. National Environmental Engineering Research Institute (NEERI) monitors ambient air quality at 30 stations covering 10 major cities.

Due to the prohibitive cost of monitoring, the number of monitoring sites has been restricted. Presently the monitoring stations are located in
 
 
 
 

STATE-WISE LOCATIONS OF NAAQM STATIONS IN INDIA

 
 

S.No.	Name of State/ Union Territories		No. of District HQs	Population (Million 1991 Census)	Persons per  Sq. Km.		% of Total Population of India		NAAQM Stations		Air Quality Monitoring Stations per Million of Population
STATES
1.	Andhra Pradesh		23	66.5	242		7.8		12		0.18
2.	Arunachal Pradesh		13	0.86	10		0.1		2		2.33
3.	Assam		23	22.4	286		2.9		5		0.22
4.	Bihar		52	86.4	497		10.2		12		0.23
5.	Delhi		7	9.4	6352		0.9		9		0.96
6.	Goa		2	1.2	316		0.2		2		1.67
7.	Gujarat		19	41.3	211		5.0		23		0.56
8.	Haryana		16	16.5	372		1.9		8		0.50
9.	Himachal Pradesh		12	5.2	93		0.6		8		1.54
10.	Jammu & Kashmir		14	7.7	76		0.9		2		0.13
11.	Karnataka		20	45.0	235		5.4		14		0.31
12.	Kerala		14	29.1	749		3.7		16		0.55
13.	Madhya Pradesh		45	66.2	149		7.5		25		0.38
14.	Maharastra		31	78.9	257		9.2		25		0.33
15.	Manipur		8	1.8	82		0.2		2		1.11
16.	Meghalaya		7	1.8	79		0.2		2		1.11
17.	Mizoram		3	0.7	33		0.1		2		2.86
18.	Nagaland		7	1.2	73		0.1		2		1.67
19.	Orissa		30	31.7	203		3.9		8		0.25
20.	Punjab		14	20.3	429		2.5		12		0.59
21.	Rajasthan		30	44.0	129		5.0		19		0.43
22.	Sikkim		4	0.4	57		0.1		-		Nil
23.	Tamilnadu		23	55.9	403		7.1		16		0.29
24.	Tripura		4	2.8	263		0.3		2		0.71
25.	Uttar Pradesh		66	139.1	473		16.2		38		0.27
26.	West Bengal		17	68.1	767		9.0		14		0.21
UNION TERRITORIES
1.	Andman-Nicobar Islands		Port Blair	0.28	34		0.03		-		Nil
2.	Chandigarh		Chandigarh	0.64	5632		0.07		3		3.13
3.	Dadra-Nagar Haveli		Silvasa	0.14	282		0.02		3		21.4
4.	Daman & Diu		Daman	0.10	907		0.01		1		10.0
5.	Lakhadweep		Kavaratti	0.05	1616		0.01		-		Nil
6.	Pondicherry		Pondicherry Karaikal, Mahe, Yamen	0.81	1642		0.09		3		3.7
						TOTAL		290

 

different land use areas, e.g. residential, industrial and commercial to get pollution values representative of that area. In addition to the monitoring stations, operated by Central/State Pollution Control Boards and Research organisations, major industries have set up monitoring stations as part of the compliance of the consent condition. The pollutants monitored at NAAQM/SAAQM stations are nitrogen dioxide (NO₂), sulphur dioxide (SO₂), suspended particulate matter (SPM) besides meteorological parameters like wind speed, wind direction, temperature and humidity at some of the stations. In addition to these three conventional parameters, NEERI monitors special parameters like ammonia (NH₃), hydrogen sulphide (H₂S), respirable suspended particulate matter (RSPM), polynuclear aromatic hydrocarbon (PAH) and heavy metals

The most important concern about the inadequacy of the air quality monitoring network is that all critical pollutants are not being monitored. Central Pollution Control Board chose only three air quality parameters when it began air quality monitoring in 1984 - daily, monthly and annual average for suspended particulate matter, sulphur dioxide and nitrogen dioxide. Meteorological information was also collected for some of the cities. Some more parameters like carbon monoxide and polynuclear aromatic hydrocarbons were included in the monitoring network but only at few locations. Short term monitoring of heavy metals, PAH, benzene and ozone have been initiated in Delhi.

The present Air quality monitoring network cannot capture the true profile of urban air pollution due to its limitations of the number of stations. The density of monitoring stations is extremely inadequate. For example, Delhi has nine monitoring stations to cover a massive area of 1485 sq. km. Therefore, one station is expected to capture the air quality profile of as much as 165 sq. km. If information from other countries is taken as a benchmark, the network density of Delhi falls woefully short of the desired number. The sulphur dioxide monitoring grid in Berlin (GERMANY) uses 31 continuously operating monitors in a grid network of 16 sq. km.

Proposed Monitoring Network

A Real Time (Continuous Automatic) Network measuring all major pollutants and providing data continuously to Central Pollution Control Board and Sate Pollution Control Board (Head Quarter), where visuals give the citywide air quality situation, is the ideal monitoring network. However, the high cost of the computerised monitoring network precludes its applications. The siting of monitoring stations is important to capture the variation in pollution concentration. A traffic centered network would need data from close proximity of the road to understand the relationship between the rate of change in urban air quality with distance from the road.

The monitoring activities in the major cities of India need to be extended to cover more pollutants and a wider geographical area. Localised air quality assessment need to be carried out to identify the specific problems and to provide recommendations for pollution abatement. It is also important that the air quality monitoring network should reflect the changing situation and concerns as well as new research results. The expansion of the monitoring activities should cover the following areas: -

. Problem Areas

Central Pollution Control Board in collaboration with the concerned State Pollution Control Boards/Pollution Control Committees in Union Territories (UTs) has identified 24 problem areas. The problem areas were identified after a thorough review of the following:

Of the 24 identified problem areas, the following areas based on the severity of air pollution are being considered for installation of real time (continuous) ambient air quality monitoring network:

- Chembur;

- Dhanbad;

- Durgapur;

- Govindgarh;

- Howrah;

- Korba;

- Singrauli;

- Talcher; and

- Vishakhapatnam.

Atleast two real time (continuous) monitoring stations with facilities to monitor sulphur dioxide, nitrogen oxides, respirable suspended particulate matter and meteorological parameters need to be installed in these areas to provide air quality

trends and the impact of the policy implementation and abatement measure undertaken for curbing air pollution. In addition to these four parameters, area related specific parameters also to be monitored at these locations. The stations will provide continuously to Central Pollution Control Board and Sate Pollution Control Board (Head Quarter).

. Traffic Centre Network

India has witnessed phenomenal increase in the number of industries and vehicles in the last decade along with the mushrooming of the city. As a consequence there has been deterioration in the urban air quality in most region of the country. There has been a proliferation of regional hot spot with severe air pollution in the last decade. The unprecedented spurt in the number of vehicles in India has emerged as the most significant contributor towards air pollution. While industrial air pollution is localised in nature, mobile sources bring entire city into the grip of severe air pollution. The routine pollutants in the urban air include sulphur dioxide, nitrogen oxides and suspended particulate matter. Besides, there is a threat from other air pollutants, e.g. carbon monoxide; respirable suspended particulate matter, ozone, benzene, polynuclear aromatic hydrocarbons and lead. Real time monitoring network is required to roll out data on an hourly basis to inform people about the current air quality. Due to increase in the traffic, traffic jams have become a regular feature in most of the cosmopolitan cities in the country thereby aggravating the problem further. Traffic centre network comprising of 5 to 6 real time monitoring stations with facilities to monitor CO, NO_x, SO₂, RSPM, O₃, Benzene and Meteorological parameters need to be developed to monitor the air quality at the major traffic corridors/intersections atleast in the cosmopolitan cities. The Cosmopolitan cities where such a network can be established are:

- Delhi,

- Mumbai,

- Chennai,

- Calcutta,

- Bangalore and

- Hyderabad

In addition to the cosmopolitan cities, traffic centre network need to be established in some large industrialised metro cities where the increase in vehicular population is substantial. Two such cities where the network can be established are Ahmedabad and Kanpur. The monitoring stations in all the cities will be linked to the main computer in State Pollution Control Boards/Central Pollution Control Board through networking and the data generated can be made used for public awareness, implementation and control measures.
 

. Air Quality Monitoring

The monitoring network being operated by Central Pollution Control Board (under the NAAQM Programme) in other cities need to be strengthened by addition of monitoring facilities for respirable suspended particulate matter. The World Bank is assisting in setting up facilities for monitoring of Respirable suspended particulate matter at the NAAQM Stations located in 23 metro cities. Facilities for monitoring additional parameters can be created depending on the growth of the city. Additionally, in the other metro cities, (besides the six cosmopolitan cities and the two metro cities i.e. Ahmedabad and Kanpur) to begin with a network of two real time monitoring stations with facilities to monitor RSPM, NO_x, SO₂, CO, O₃ and Meteorological parameters can be installed which can be extended further to cover more areas depending upon the growth of the vehicular population and industrialisation of the city. By the year, 2001, it is expected that there will be 40 metro cities in India, (including six cosmopolitan cities) having population of more than one million. Proposed cities to be covered in the programme are: -

- Pune,

- Bhopal,

- Surat,

- Patna,

- Jaipur,

- Nagpur,

- Indore,

- Ranchi,

- Vadodara,
- Jamshedpur,

- Vishakhapatnam,

- Dhanbad,

- Madurai,

- Jabalpur,

- Coimbatore,

- Vijaywada,

- Varanasi,

- Jodhpur,

- Cochin,

- Ludhiana,

- Srinagar,

- Meerut,

- Agra,

- Gwalior,

- Tiruchirapalli,

- Alllahabad,

- Amritsar,

- Hubli,

- Dharwad,

- Salem and

- Thiruvananthapuram.

The local Industrial Development Agencies/Corporation should establish monitoring network for assessing the air quality in the Industrial estates.

Sensitive Areas

Most of the monitoring activities under the NAAQM and SAAQM are confined to industrial, residential and commercial areas. Hardly any monitoring facility has been established in the reserved forests, wild life sanctuaries or near the monuments. To study the impact of air pollution in these areas, atleast two real time monitoring stations need to be established in about 10 sensitive areas covering different ambits of activity. The parameters to be monitored are SO₂, NO_x, O₃ and meteorological besides the specific pollutants which can be expected from the activities in the surrounding areas.

Wet Deposition Study

Atmospheric deposition studies provide valuable information for the understanding of the entire atmospheric cycle-emissions, transport, transformations and deposition. The composition of wet deposition actually reflects the composition of the atmosphere through which it falls. Therefore, rainwater chemistry data can be used to explain the composition and chemistry of ambient air, cloud droplets and air-sea exchange.

At present there is very little data to assess the extent of wet deposition in the country. Wet deposition studies will be taken up at Delhi, Calcutta, Bangalore, Kanpur, Vadodara, Bhopal, Shillong and Kochi

Operation & Maintenance

The monitoring sites have been restricted because of the prohibitive cost of monitoring. CPCB/SPCBs alone cannot accomplish the strengthening of the monitoring network. Financial assistance from other agencies would be required in this endeavour. However, operation & maintenance (O&M) cost for running the network can be met by:

- Contribution from State Governments;

- Out of 20% Cess available at Ministry of Environment & Forests;

- From State Pollution Control Boards resources;

- Assistance from Central Pollution Control Board.

(All industries consuming water have to pay Cess, the rate of which depends upon the quality of waste water discharged. 80% of the Cess money collected is provided to SPCBs while Ministry of Environment & Forests retains 20% for funding specific projects.)

The data collected from the monitoring network could be made available to the industries on charge basis and the money collected used for meeting part of the O&M cost.

Nearly all the major industries are operating monitoring stations as part of their compliance of the consent condition. Stations of the industries falling within the zone of the influence of the National/State monitoring network can be taken off and instead the industry can pay for the monitoring station being operated by CPCB/ SPCBs. In some areas having high density of major industries, the number of stations is very high and many stations provide assessment of the same area. These stations need to be relocated and integrated in the National Monitoring Network and the industry can pay for the operation and maintenance of those relocated stations.

Air Quality Criteria and Standards

Till recent years, several countries in the South Asia Region have been burdened with environmental issues connected with poverty and under development. The hallmarks of which are run away growth in population lack of sanitation, malnutrition and other such basic human needs. These problems necessarily prompted national initiatives for rapid economic growth. Ironically the process of economic upliftment through industrial development has brought in its wake a series of emerging issues having a direct bearing on the environmental quality. Air pollution has its impact at the local as well as at the regional level. Monitoring and assessment of air pollution load from different sources and their impacts on the affected population and on the environment are the pre-requisites for development of strategy and action plans. As on date, monitoring network is virtually non-existent in the SACEP region except for India where a network of manual monitoring station is being operated by CPCB/SPCBs. Proper monitoring network needs to be established in the Region for assessment of the air quality. In the other countries of SACEP region monitoring stations can be established on the land use pattern, i.e. industrial, residential and commercial as done in India. To begin with monitoring of the criteria pollutants, like sulphur dioxide, nitrogen dioxide and respirable suspended particulate matter can be taken up. Monitoring for specific pollutants like Carbon monoxide, lead and ozone can be initiated at some of the traffic intersections in few bigger cities. Once the system is in place, efforts for extension of the network can be taken up.

Some of the countries in SACEP region have laid down ambient air quality standards, which relate to the criteria pollutants, e.g., suspended particulate matter, sulphur dioxide and nitrogen dioxide. Reflecting its size India has taken the approach for setting different air quality standards for different types of locations with more stringent standards for conservation and tourist areas, less strict standards for residential and rural area and more permissible standards to industrial area of heavy traffic (Table - 2).

The strategy for air pollution control entails a multi-pronged approach including legal, technological and economic instruments. Alongside, strengthening of instrumental mechanisms for co-ordination at various levels is a must for effective air quality management. Monitoring and assessment of pollution and its impacts, enforcement of legal provisions, promotion of clean fuels and technologies, fiscal incentives and public participation are among the key components for formulation of air quality management strategy. The uniform ambient air quality standards need to be laid down in the region along with the targets for achieving the air quality objectives. The ambient air quality standards would be prescribed for short as well as long term objectives considering the achievable targets in a fixed time frame. The source specific standards for different categories of air polluting industries are to be linked with the health hazards, available technologies and cost implications.

It is important that the data generated from the monitoring network within the region is reliable, precise and of acceptable quality. For inter comparison of the data collected from the monitoring network installed/proposed uniformity in sampling and analytical procedure is required. In India, assessment of pollutants like, sulphur dioxide, nitrogen dioxide, suspended particulate matter, respirable suspended particulate matter, lead, carbon monoxide and polynuclear aromatic hydrocarbon have been done for the last many years. Methodology for sampling and analysis of these parameters have been well established and authenticated. Method of measurement for the criteria pollutants are give in Table - 3. As the methods of measurement in India are well established. These can be used by countries in the region while establishing their monitoring network. On the job training in measurement of the criteria pollutants can be provided to officials from countries in the region by Central Pollution Control Board.

Data Utilisation

Monitoring network will generate huge amount of data, which need to be properly collected, collated, evaluated, interpreted and compiled in the form of reports. The data will provide information on the success of the abatement measures, air quality trend, and impact of policies etc. Good public information system is needed for air pollution in severely polluted hot spots in countries of the region. As pollution control cannot be accomplished by the Government agencies alone awareness has to be created among the general public on the air quality. This can be done through awareness campaigns involving print and electronic media along with cyber space The data generated from the monitoring network should be regularly published in the newspaper and also made available on Internet. Leaflet/brochures need to be prepared regularly for distribution to the general public and other sectors of the societies informing them of the action taken and what further needs to be done for improvement of the environment. The data collected should be compiled highlighting needs of the future action and enlisting the rate of success of the measures already taken which can be used by the policy makers for further action.
 
 

Air Quality Monitoring Techniques for various Air Pollutants

 
 

Air Pollutants	Monitoring Technique/Method	Principle	Measuring Range
Sulphur dioxide	Automatic:	Pulsed fluorescence	0.001-2 PPM
	SO2 Analyser
	Calorimetric:
	Improved West & Gaeke (Sodium tetra-chloro-mercurate) method	Absorption followed by calorimetric	4-10.50 m g/m3
Nitrogen oxides (NO-NO2-NOx)	Automatic:
	NOx Analyser	Gas Phase Chemiluminiscence	0-2 PPM
	Calorimetric:
	Jacob & Hochhieser Method (Sodium Arsenite Method)	Absorption followed by calorimetric	3-420 m g/m3
Suspended particulate matter (SPM)	High Volume Method	Sampling by High Volume Sampler Average flow rate not less than 1.1 m3/min	5-10000 m g/m3 0.3-100 m m particle size
Respirable suspended particulate matter (RSPM)	Respirable suspended particulate matter (RSPM) sampler	Sampling by RSPM sampler	0.3-100 m m particle size
Carbon monoxide	Automatic:
	CO Analyser	Non dispersive Infra red (NIDR) spectroscopy	0.1-10 PPM
	Gas chromatographic-FID detector	GC/FID	0.3-100 PPM
	Manual:
	Detector tubes		various ranges
Ozone	Automatic:
	Ozone Analyser	Chemiluminiscence	0.002-1 PPM
	Manual:
	Neutral potassium Iodide absorption method	Absorption followed by calorimetric	0.01-10 PPM
Benzene	Gas chromatographic-FID detector	Activated charcoal adsorption followed by GC/FID analysis	01.-100 PPB
	Manual:
	Detector Tubes		various ranges
Poly aromatic hydrocarbons (PAH)	Gas chromatographic-FID detector	Extraction, clean up followed by GC/FID analysis	0.002-2.0 m g/m3
Lead	Atomic Absorption Spectrometer	High volume sampling using EPM 2000 filter paper. Digestion and AAS analysis	5 ng/m3

Regional centre where information from all the countries can be received and compiled needs to be established in one of the country of the region. The regional office will be responsible for preparing reports at regional level, identifying thrust areas for monitoring, conducting Quality Assurance exercises, establishing standard methodology for measurement of pollutants and even considering adoption of common standards/norms for industrial emissions, fuel quality and vehicular emissions besides assisting in organising training programmes

Transport of Air Pollutants

Air pollution has its impacts at the local as well as regional level. The long-range impacts of air pollution were evident in the recent Indonesian forest fires. The area affected by the haze spread for more than 3200 km. east to west covering South Asian countries and affecting about 70 million people. While atmospheric transport helps in discharging of air pollutants, the impacts are felt in distant places for from the source of emissions. In the last few years many institutes/research organisations have been able to develop mathematical models for predicting the air quality in the city. However, efforts for developing model for predicting long range (transboundary) movement of air pollutants have not been made so far. Institutes like National Physical Laboratory (NPL) and Indian Institute of Technology (IIT) which have experience in the area of modeling can be asked to develop mathematical model for prediction of transboundary movement of air pollutants.

1.2 NATIONAL EMISSION INVENTORIES

For affecting the air quality planning, it is important to know the precise share of emissions from different polluting sources. This can only be done by developing a comprehensive source wise emission inventory of air pollution to identify the type of polluting sources in an urban area together with the amount of each pollutant discharged in a specified period. Besides, an emission inventory should be updated regularly to account for the new sources of pollution being added over time. Emission inventories are a vital part of air quality management system as decision on emission reduction measures would need to be based on a clear understanding of how much each emission source contributes to the air pollution problem. Presently this is a weak link in air quality planning in India, as meaningful emission factors for different sources to make such inventories are not available.

Information in an inventory should include emission rates from individual point sources, e.g. industries and power stations, area sources like cooking and garbage burning and line sources, e.g. motor vehicles plying on the road. Emission sources are grouped according to fuel types, e.g. coal, light and heavy fuel, petrol and diesel, gas and solid wastes.

Estimating emission rates of different sources of pollution or emission factor is crucial for developing emission inventories. However, calculation of emission factor of different sources would need data on emissions from extensive surveys on different parameters that have a bearing on emissions.

Some attempts have been made to develop emission factor for motor vehicle but these are inadequate. Given the complex nature of vehicular pollution because of the diversity of the vehicles in terms of age, size, distance traveled and fuel used good emission factors are needed to understand the impact of growth in the number of vehicles. In India, comprehensive emission factors have not been developed. Two sets of emission factors for vehicles in India have been calculated by Indian Institute of Petroleum (IIP) and Automotive Research Association of India (ARAI), Pune (Tables - 4 & 5). Emission factors developed by agencies though not very comprehensive are widely used by air quality regulators and researchers to calculate pollution load from transport sector in India.

Difficulties in compiling inventories also arises in case of pollutants, e.g. Ozone which are not emitted directly into the atmosphere but are secondary pollutants formed through chemical interactions of other pollutants. Inventories of such pollutants would need sophisticated models incorporating chemical reactions that transform primary pollutants into secondary pollutants

Methodology and Emission Factor
Each of the four pollutants under consideration, i.e. sulphur dioxide, nitrogen dioxide, SPM and ammonia has different emission sources, for example emissions of sulphur dioxide are mainly associated with the combustion of sulphur containing fossil fuel. Other activities giving rise to emission include, process emissions, non-ferrous metal smelting (copper, lead and zinc), oil refineries, pulp & paper industries and sulphuric acid production.

Sources of oxides of nitrogen are mainly associated with fossil and biomass fuel combustion and biomass burning. The important process emission source of oxides of nitrogen, nitric acid production, which is predominantly used in fertilizer manufacturing. Sources of suspended particulate matter are associated with the industrial as well as human activities, which includes industrial pollutants, power generation, biomass burning and vehicular traffic. Ammonia emissions are from rice paddy cultivation, enteric fermentation in livestock, fertilizer production landfill and underground sewerage (waste).
 
 

Vehicle Type	CO (g/km)	HC (g/km)	NOx (g/km)	SO2* (g/km)	Lead* (g/km)	Particulate** (g/km)
Two-Wheelers	8.30	5.18	-	0.013	0.004	-
Cars	24.03	3.57	1.57	0.053	0.0117	-
Three-Wheelers	12.25	7.77	-	0.029	0.009	-
Urban Buses	4.381	1.327	8.281	1.441	-	0.275
Trucks	3.425	1.327	6.475	1.127	-	0.450
Light Commercial Vehicles	1.30	0.50	2.50	0.40	-	0.100

** Estimate based on 13 mode cycle. (On a chassis dynamometer, a vehicle is made to pass through periods of acceleration and deceleration and idling at regular intervals and each mode of this kind represents one cycle. In the 13 mode cycle, it would be made to pass through 13 such cycles. The emission level for each mode is measured and then an average is taken to arrive at a mass emission level.)

Source:

ARAI, 1998, Determination of Emission Factor for Indian Automotive Vehicles and Emission Inventory, paper presented at Workshop on Integrated Approach to Vehicular Pollution Control in Delhi (April 16-18, 1998), New Delhi, Subgroup II: Vehicle and Fuel Technologies, p 101.
 
 

Emissions can be estimated sector wise as each of these emission source categories belongs to different sector. Energy sectors constitute of emissions from coal mining, oil and natural gas extraction, oil and natural gas refining/processing and power generation. The industrial sector emissions are from fossil fuel combustion in manufacturing of steel, cement, fertilizer, brick and nitric acid manufacturing. The transport sector includes emissions due to fossil fuel combustion from road, rail, aviation and shipping mode of transport. The agricultural sector includes emissions from rice paddy cultivation, livestock related emissions, soil and other agricultural emissions and burning of crops residue lastly the residential and commercial sector including emissions from landfill and waste water disposal and biomass consumption.

The sector identification of emission source categories is important since emissions of different pollutants depend upon the sector. Thus, to estimate the total emissions for India for a particular pollutant emissions from all the Indian districts from combustion of different fossil fuels (source categories) in different sectors and also due to industrial activities have been taken. The major emission coefficient relevant to the Indian conditions and wherever not available WHO emissions factor have been applied. The emissions factor for estimating ammonia emission from enteric fermentation in animal and animal manure management are not available. The ALGAS INDIA, 1998 and the IPCC guidelines, 1997 give methane emission factor but ammonia emission factors are not available. Similarly for estimation of ammonia, emissions factor for rice paddy fields are not available.

Establishment of Emission Inventories

It is important to put sufficient resources into the establishment of emission inventories in cities. This is one of the main pillars of thorough air quality assessment. The major sources of sulphur dioxide, oxides of nitrogen, suspended particulate matter and ammonia can be divided into three categories:

1. Line Sources;

2. Area Sources; and

3. Point Sources.

It is impracticable to measure every emission sources in a large urban area with a population of millions. Majority of emissions are therefore, proposed to be estimated from local information, e.g. fuel consumption, vehicle km. traveled, transportation models, traffic service, process in house, raw material used, material balance etc.
 

The road activity and emission distribution can also be calculated by using dispersion modeling programme system, developed by NILU. MOBILE-5a is another model commonly used to estimate emissions from mobile sources. As this model was developed for US vehicle, it requires adjustment to match local conditions, e.g. characterization of the motor vehicle fleet, fuels, driving pattern and ambient climatic condition.

Before embarking on any programme for building of the inventories in the sub region efforts have to be made to develop emissions factor for sulphur dioxide, oxides of nitrogen, SPM and ammonia from various sources. At the same time, the methodology to be used for estimating the total emissions needs to be defined. The methodology adopted should take into consideration the shortcoming in the available data record. In the first instance, regular upgradation of the inventory base is required. Once reliable and efficient database has been prepared, upgradation of the inventory can be done regularly. The emission factor available in the sub region and developed based upon the local condition should be used wherever possible.
Pollutants emitted from specific fuel sources and combustion or non combustion technology must be identified. Measurement and reliable data collection are major tasks. Pollutant and emissions measurements are needed at the sources and also in the ambient air. The measurements will be ground based and air borne based. There is a need to quantify these pollutants and emissions and analyse their transport and exposure.

Modeling should be the primary tool to develop such a database. The tasks that need to be accomplished are: