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Air quality in the Karachi metropolitan area
Reports Air quality in the Karachi metropolitan area Information about air quality in Third World cities is sparse, but air pollution problems are believed to be serious and increasing. The authors describe recent efforts by the Pakistan Space and Upper Atmosphere Commission (SUPARCO) to identify major pollutants, including the particulate content of ambient air; aerosols; and the content of gases such as ozone, nitrogen oxides, sulphur dioxide, and carbon monoxide.
Karachi is the largest industrial and commercial centre in Pakistan. It contains about 7 million people, and offers the country’s largest source of employment and the greatest number of business opportunities. Consequently, more and more people are migrating into the metropolitan area. The Karachi Development Authority estimates that the urban population is growing at about 6% per year, with about half of the newcomers arriving from rural ‘up-country’ communities. It has been estimated that the urbanized area expanded from 250 km2 in 1972 to 3.53 km2 in 1982. The use of gasoline-powered vehicles is also increasing at a rapid rate. A Pakistan government report estimates that there are about 486 000 vehicles in the city and that their numbers are increasing at 20% per year. As a result of rapid growth and a shortage of public funds, the provision of housing and other civic amenities is under heavy strain. Air pollution in Karachi is influenced by the monsoon climatic regime, by the city’s coastal site, and by the fact that most of the industry is located towards the north-eastern (inland) sector of Karachi (Figure 1). Annual precipitation averages only 20 mm, with over 60% falling in July and August. During this period, winds of the South-west monsoon blow off the ocean and carry pollutants inland at average speeds of l&20 knots. During the North-east monsoons (JanuaryMarch), winds blow towards the sea at around 5-10 knots. As a result, pollu-
GLOBAL
ENVIRONMENTAL
tants are pushed towards the city during the North-east monsoon and taken away from it during the South-west monsoon.
Air pollution monitoring Air pollution measurements are conducted regularly at three different fixed sites in the Karachi metropolitan area. Fixed point surveys, however, are of limited value because they may be unrepresentative. Pollution concentrations tend to be dominated by a single source that may or may not be located near a monitoring station. They are also located at some distance from busy streets, and do not reflect the
5 km
N
0 Monitoring 0
I
Figure 1. The metropolitan
CHANGE
June
1992
conditions experienced by people who use the main traffic arteries. In an effort to overcome these limitations, and to provide an improved assessment of pollution levels in the city, the Space and Upper Atmosphere Research Commission (SUPARCO) conducted a rapid assessment of air pollution sources and pollution transport at thirteen different locations scattered throughout the metropolitan area (Figure 1). Measurements of air pollution and meteorological conditions were carried out simultaneously between 6 am and 9 pm for 15 consecutive days. Major findings are discussed below, and are summarized in Table 1. Table 2 indicates the impact of aerosols on air pollution in the Karachi area. Carbon monoxide and carbon dioxide. The internal combustion engine is responsible for most of the urban air pollution in Karachi. Carbon monoxide and carbon dioxide loads in the central business district mirror the daily traffic flows, with the highest concentrations during rush hours (7-9 am; 4-6 pm). Along busy streets, carbon monoxide levels in ambient air reach 10-15 ppm and carbon dioxide levels exceed 370 ppm. Hydrocarbons _ in the form of unburnt petroleum vapours from cranks, fuel systems and exhausts - are contributing by the use
sites
eZa
Residential
m
Industrial
University
A Cement l Oil-fired V Steel
factory power
plants
and
refineries
mill
city of Karachi.
157
Reports of vehicles fuelling.
or are due to careless
re-
Nitrogen oxide. Problems with nitrogen oxide are also evident. These chemicals are initiators of photochemica1 smog. NO2 levels are not within US ambient air quality standards (ie 0.05 ppm annual mean; [email protected] ppm one hour mean). Maximum NO2 (0.30.5 ppm concentrations were observed during the daytime during 6 am-9 pm. In downtown Karachi, most of these compounds originate from the combustion of gasoline or diesel fuel in an ever-increasing number of vehicles. Refuse burning contributes only an insignificant amount. Sulphur. Emissions in the form of SO2 are mostly due to the burning of fuels that contain small quantities of sulphur. Coal combustion accounts for almost all sulphur emissions around Pakistan Steel Mills. It is believed that this facility imports about 1 360 000 tonnes of coal every year to produce coke. This coal contains 2-3% of sulphur by weight. Petroleum contains a variety of sulphur compounds, including mercaptans; organic sulphides; cyclic compounds; thiophene and polysulphides and the sulphur content ranges between 0.1% and 3%. According to a recent survey, 486 000 vehicles in Karachi travel a total distance of 2 190 000 km per day. This is equivalent to consuming 2 X lo6 litres of petroleum or diesel fuel per day.
Therefore, the sulphur emission caused by vehicles in Karachi is about 3 tonnes per day (assuming 0.12 kg of sulphur emission per lo3 km).’ Considering the fact that 609 549 tonnes of furnace oil (3.5% sulphur by weight) are consumed each year by oil-fired power plants at Port Qasim and Korangi, an estimated 40 000 tonnes of sulphur per year are being produced from power plants. Other power plants use about 650 million m3 of natural gas per year. This produces 75 tonnes of SO2 equivalent each year. Finally, oil refineries are estimated to produce sulphur emissions of around 3000 tonnes per year. Despite the relatively high levels of sulphur being emitted, SUPARCO measurements indicate that sea breezes quickly disperse most of it. Even at roadside locations, levels of SO, are well within limits of 0.50 ppm hourly means. Ozone monitoring. Apart from measurements of surface ozone undertaken during the rapid assessment project, three sites were selected for continuing surface ozone monitoring. These were located along a transect that included one site upwind from major industries and urban traffic concentrations (site 1); another site at the heart of the city (site 2); and yet another in the north of the city, downwind from most pollutants (site 3). Over the past two years, Karachi’s surface ozone concentrations have exhibited marked afternoon maximums
Table 2. Concentrations of trace constituents in bulk aerosols (high-volume) and non-respirable aerosols (size-fractionated).
and respirable
July SPR Naa W Al” SC
Br Pb Sb Fea Mn V Ni Cr Se
16.0 6.0 1.4 93 93 2.4 4.2 76 13 17 26 2.6
SPR Bulk
RP
SOM NRP
2.1 3.3 0.3 1.8 45 275 IO 5.6 131 18 ND 24 2.3
0.09 0.04 0.24 0.05 11 4.0
4.9 8.6 0.64 0.17 5 0.2
27 February - 6 March 1967 STE SPR RP NRP RP NRP
RP
0.3 0.6 2.2 0.2 11 214 5.4 1 .o 56 7.3 14 11 0.7
0.28 0.40 2.4 0.33 19 65 0.73 3.7 280 14 162 11 1.0
0.76 1.24 2.5 0.37 3 44 I .o 1.5 38 4.9 3.8 12 0.4
0.25 0.58 1 .o 0.14 24 287 8.0 0.56 26 4.1 3.3 6.0 0.5
0.8 1.5 1.6 0.29 7 56 1.3 1.2 29 3.7 2.8 9.0 0.3
PSM NRP 0.54 1.23 2.6 0.60 6 E3 7.5 350 7.3 5.5 11 0.6
Notes: a These concentrations are given in Kg/m2 - all others are in qglm’. RP - respirable (less than 1 rm) NRP - non-respirable (l-10 pm); SOM - Sonmiani Beach: STE - SITE, Karachi; SPR SPARCENT; PSM - Pakistan Steel Mill.
158
GLOBAL
ENVIRONMENTAL
CHANGE
June 1992
Reports
between 12 noon and 3 pm. This occurs irrespective of weather conditions and site location. Results from the most recent survey show that ozone maxima are higher and are delayed at sites 2 and 3 compared to site 1. For example, ozone levels are 25 ppb at site 1; 50 ppb at site 2; and 65 ppb at site 3. This clearly illustrates the contribution of local photochemical synthesis of ozone in the city’s polluted air. Purticulutes. In Karachi, particulates come from both natural and manmade sources. Sea salt is the primary natural source. Man-made particle emissions come from cars; trucks; steel mills; cement plants; ceramic industries; and solid waste incineration, among others. Pakistan Steel Mills is the largest single source of man-made particulates. Over a three-year period, measurements of daily total suspended particulates (TSP) were made at three sites. From these it was determined that TSP levels do not vary significantly from day to day, averaging 239 ugm, +62 (March); 233 *55 (May); and 268 +57 (June). A number of heavy elements are found in suspension in Karachi’s air. Lead from leaded gasoline is common, at concentrations that are 3-7 times greater than in North American cities. The soil of Karachi contributes significant quantities of aluminium, cadmium, selenium, molybdenum, iron, cobalt, hydrofluorine, and thorium. Quantities of these elements are up to 8 times greater than in the air of large US cities. Most of the silicates and limestone components in the air are attributed to cement plants at Gulshan-e-Iqbal and the SITE area. Silicate and limestone account for almost half of the aerosol mass. High concentrations of respirable silicate particles are known to cause pulmonary diseases (eg silicosis).
Health Many parts of the Karachi metropolitan area are exposed to highly polluted air (eg Jinnah Road, Sadar, Korangi). Most of the pollution comes from the combustion of vehicular
GLOBAL
ENVIRONMENTAL
fuels, power plants, tanneries, and textile mills. The dust that is emitted by two cement plants poses a particularly serious health problem. Unlike more enlightened cities elsewhere, Karachi permits such factories to be erected near residential areas without requiring electrostatic filters. Although sea breezes ensure that pollutants from many industrial plants are not dispersed over the most heavily populated areas, the effect of pollutants on nearby populations may be considerable and large numbers of people are exposed to high levels of air pollutants in the workplace. Dust is the major culprit, but acidic and caustic vapours, hydrocarbons, fluorides, metals and other pollutants are also involved. Almost 80% of vehicles emit black smoke due to improper combustion of fuels. Most are poorly maintained because repairs are too costly. The smoke is loaded with dangerous chemicals such as hydrocarbons; nitrogen oxides; sulphur; paraffins; olefines; polynuclear aromatics; and aldehydes. Moreover, high lead concentrations in gasoline (1.5-2 g/litre) lead to contamination by toxic lead. Morbidity and mortality rates are affected by many other factors in addition to air pollution, and it will be necessary to take account of them before the effects of polluted air on
human health can be clearly distinguished. Nonetheless, it is important for countries like Pakistan to establish national ambient air quality standards that take specific health and welfare effects into consideration. National standards and supporting regulations can satisfy a variety of purposes. These include: (a) protecting health and welfare in circumstances where long-term, low-level, irreversible impacts are suspected but not sufficiently quantified to permit the formulation of specific pollutant controls: (b) protecting people against locally high concentrations of hazardous pollutants emitted from a small number of isolated sources; (c) establishing limits on individual sources of pollution that have significant aggregate effects; (d) discouraging the migration of industry to regions with poor or non-existent emission restrictions; and (e) providing a vehicle for adopting energy and fuel savings policies. Badar Ghauri Manzar Salam M. I. Mirza SUPARCO Karachi, Pakistan
‘Rapid Assessment of Sources of Air, Water and Land Pollution, Publication No 62, World Health Organisation, Geneva.
Global environmental change at the Pacific Science Congress At the end of May 1991, Honolulu was the venue of the XVII Pacific Science Congress. It was the most recent of the major gatherings, every four years, of the Pacific Science Association, now over seventy years old. The meeting was attended by more than 1500 scientists from over 50 countries. The programme, with the overall theme ‘The Challenge of Change ‘, was built around six sections among which global environmental change in the Pacific figured prominently indeed.
Aside from ‘Global Environmental Change, Pacific Aspects’, the sections of the Pacific Science Congress were: ‘Population Health and Social Change’; ‘Science and Culture’; ‘Biological Diversity’; ‘Technologies for Development: Prospects for the 21st Century’; and ‘Dynamics of the
CHANGE
June 1992
Earth and the Heavens, the Pacific Arena’. I will try here to do some, albeit necessarily selective, justice to the extremely varied detailed reports and more general contributions to what we know or should know about past, ongoing and impending changes in geophysical, chemical and biolog-
Karachi is the largest industrial and commercial centre in Pakistan. It contains about 7 million people, and offers the country’s largest source of employment and the greatest number of business opportunities. Consequently, more and more people are migrating into the metropolitan area. The Karachi Development Authority estimates that the urban population is growing at about 6% per year, with about half of the newcomers arriving from rural ‘up-country’ communities. It has been estimated that the urbanized area expanded from 250 km2 in 1972 to 3.53 km2 in 1982. The use of gasoline-powered vehicles is also increasing at a rapid rate. A Pakistan government report estimates that there are about 486 000 vehicles in the city and that their numbers are increasing at 20% per year. As a result of rapid growth and a shortage of public funds, the provision of housing and other civic amenities is under heavy strain. Air pollution in Karachi is influenced by the monsoon climatic regime, by the city’s coastal site, and by the fact that most of the industry is located towards the north-eastern (inland) sector of Karachi (Figure 1). Annual precipitation averages only 20 mm, with over 60% falling in July and August. During this period, winds of the South-west monsoon blow off the ocean and carry pollutants inland at average speeds of l&20 knots. During the North-east monsoons (JanuaryMarch), winds blow towards the sea at around 5-10 knots. As a result, pollu-
GLOBAL
ENVIRONMENTAL
tants are pushed towards the city during the North-east monsoon and taken away from it during the South-west monsoon.
Air pollution monitoring Air pollution measurements are conducted regularly at three different fixed sites in the Karachi metropolitan area. Fixed point surveys, however, are of limited value because they may be unrepresentative. Pollution concentrations tend to be dominated by a single source that may or may not be located near a monitoring station. They are also located at some distance from busy streets, and do not reflect the
5 km
N
0 Monitoring 0
I
Figure 1. The metropolitan
CHANGE
June
1992
conditions experienced by people who use the main traffic arteries. In an effort to overcome these limitations, and to provide an improved assessment of pollution levels in the city, the Space and Upper Atmosphere Research Commission (SUPARCO) conducted a rapid assessment of air pollution sources and pollution transport at thirteen different locations scattered throughout the metropolitan area (Figure 1). Measurements of air pollution and meteorological conditions were carried out simultaneously between 6 am and 9 pm for 15 consecutive days. Major findings are discussed below, and are summarized in Table 1. Table 2 indicates the impact of aerosols on air pollution in the Karachi area. Carbon monoxide and carbon dioxide. The internal combustion engine is responsible for most of the urban air pollution in Karachi. Carbon monoxide and carbon dioxide loads in the central business district mirror the daily traffic flows, with the highest concentrations during rush hours (7-9 am; 4-6 pm). Along busy streets, carbon monoxide levels in ambient air reach 10-15 ppm and carbon dioxide levels exceed 370 ppm. Hydrocarbons _ in the form of unburnt petroleum vapours from cranks, fuel systems and exhausts - are contributing by the use
sites
eZa
Residential
m
Industrial
University
A Cement l Oil-fired V Steel
factory power
plants
and
refineries
mill
city of Karachi.
157
Reports of vehicles fuelling.
or are due to careless
re-
Nitrogen oxide. Problems with nitrogen oxide are also evident. These chemicals are initiators of photochemica1 smog. NO2 levels are not within US ambient air quality standards (ie 0.05 ppm annual mean; [email protected] ppm one hour mean). Maximum NO2 (0.30.5 ppm concentrations were observed during the daytime during 6 am-9 pm. In downtown Karachi, most of these compounds originate from the combustion of gasoline or diesel fuel in an ever-increasing number of vehicles. Refuse burning contributes only an insignificant amount. Sulphur. Emissions in the form of SO2 are mostly due to the burning of fuels that contain small quantities of sulphur. Coal combustion accounts for almost all sulphur emissions around Pakistan Steel Mills. It is believed that this facility imports about 1 360 000 tonnes of coal every year to produce coke. This coal contains 2-3% of sulphur by weight. Petroleum contains a variety of sulphur compounds, including mercaptans; organic sulphides; cyclic compounds; thiophene and polysulphides and the sulphur content ranges between 0.1% and 3%. According to a recent survey, 486 000 vehicles in Karachi travel a total distance of 2 190 000 km per day. This is equivalent to consuming 2 X lo6 litres of petroleum or diesel fuel per day.
Therefore, the sulphur emission caused by vehicles in Karachi is about 3 tonnes per day (assuming 0.12 kg of sulphur emission per lo3 km).’ Considering the fact that 609 549 tonnes of furnace oil (3.5% sulphur by weight) are consumed each year by oil-fired power plants at Port Qasim and Korangi, an estimated 40 000 tonnes of sulphur per year are being produced from power plants. Other power plants use about 650 million m3 of natural gas per year. This produces 75 tonnes of SO2 equivalent each year. Finally, oil refineries are estimated to produce sulphur emissions of around 3000 tonnes per year. Despite the relatively high levels of sulphur being emitted, SUPARCO measurements indicate that sea breezes quickly disperse most of it. Even at roadside locations, levels of SO, are well within limits of 0.50 ppm hourly means. Ozone monitoring. Apart from measurements of surface ozone undertaken during the rapid assessment project, three sites were selected for continuing surface ozone monitoring. These were located along a transect that included one site upwind from major industries and urban traffic concentrations (site 1); another site at the heart of the city (site 2); and yet another in the north of the city, downwind from most pollutants (site 3). Over the past two years, Karachi’s surface ozone concentrations have exhibited marked afternoon maximums
Table 2. Concentrations of trace constituents in bulk aerosols (high-volume) and non-respirable aerosols (size-fractionated).
and respirable
July SPR Naa W Al” SC
Br Pb Sb Fea Mn V Ni Cr Se
16.0 6.0 1.4 93 93 2.4 4.2 76 13 17 26 2.6
SPR Bulk
RP
SOM NRP
2.1 3.3 0.3 1.8 45 275 IO 5.6 131 18 ND 24 2.3
0.09 0.04 0.24 0.05 11 4.0
4.9 8.6 0.64 0.17 5 0.2
27 February - 6 March 1967 STE SPR RP NRP RP NRP
RP
0.3 0.6 2.2 0.2 11 214 5.4 1 .o 56 7.3 14 11 0.7
0.28 0.40 2.4 0.33 19 65 0.73 3.7 280 14 162 11 1.0
0.76 1.24 2.5 0.37 3 44 I .o 1.5 38 4.9 3.8 12 0.4
0.25 0.58 1 .o 0.14 24 287 8.0 0.56 26 4.1 3.3 6.0 0.5
0.8 1.5 1.6 0.29 7 56 1.3 1.2 29 3.7 2.8 9.0 0.3
PSM NRP 0.54 1.23 2.6 0.60 6 E3 7.5 350 7.3 5.5 11 0.6
Notes: a These concentrations are given in Kg/m2 - all others are in qglm’. RP - respirable (less than 1 rm) NRP - non-respirable (l-10 pm); SOM - Sonmiani Beach: STE - SITE, Karachi; SPR SPARCENT; PSM - Pakistan Steel Mill.
158
GLOBAL
ENVIRONMENTAL
CHANGE
June 1992
Reports
between 12 noon and 3 pm. This occurs irrespective of weather conditions and site location. Results from the most recent survey show that ozone maxima are higher and are delayed at sites 2 and 3 compared to site 1. For example, ozone levels are 25 ppb at site 1; 50 ppb at site 2; and 65 ppb at site 3. This clearly illustrates the contribution of local photochemical synthesis of ozone in the city’s polluted air. Purticulutes. In Karachi, particulates come from both natural and manmade sources. Sea salt is the primary natural source. Man-made particle emissions come from cars; trucks; steel mills; cement plants; ceramic industries; and solid waste incineration, among others. Pakistan Steel Mills is the largest single source of man-made particulates. Over a three-year period, measurements of daily total suspended particulates (TSP) were made at three sites. From these it was determined that TSP levels do not vary significantly from day to day, averaging 239 ugm, +62 (March); 233 *55 (May); and 268 +57 (June). A number of heavy elements are found in suspension in Karachi’s air. Lead from leaded gasoline is common, at concentrations that are 3-7 times greater than in North American cities. The soil of Karachi contributes significant quantities of aluminium, cadmium, selenium, molybdenum, iron, cobalt, hydrofluorine, and thorium. Quantities of these elements are up to 8 times greater than in the air of large US cities. Most of the silicates and limestone components in the air are attributed to cement plants at Gulshan-e-Iqbal and the SITE area. Silicate and limestone account for almost half of the aerosol mass. High concentrations of respirable silicate particles are known to cause pulmonary diseases (eg silicosis).
Health Many parts of the Karachi metropolitan area are exposed to highly polluted air (eg Jinnah Road, Sadar, Korangi). Most of the pollution comes from the combustion of vehicular
GLOBAL
ENVIRONMENTAL
fuels, power plants, tanneries, and textile mills. The dust that is emitted by two cement plants poses a particularly serious health problem. Unlike more enlightened cities elsewhere, Karachi permits such factories to be erected near residential areas without requiring electrostatic filters. Although sea breezes ensure that pollutants from many industrial plants are not dispersed over the most heavily populated areas, the effect of pollutants on nearby populations may be considerable and large numbers of people are exposed to high levels of air pollutants in the workplace. Dust is the major culprit, but acidic and caustic vapours, hydrocarbons, fluorides, metals and other pollutants are also involved. Almost 80% of vehicles emit black smoke due to improper combustion of fuels. Most are poorly maintained because repairs are too costly. The smoke is loaded with dangerous chemicals such as hydrocarbons; nitrogen oxides; sulphur; paraffins; olefines; polynuclear aromatics; and aldehydes. Moreover, high lead concentrations in gasoline (1.5-2 g/litre) lead to contamination by toxic lead. Morbidity and mortality rates are affected by many other factors in addition to air pollution, and it will be necessary to take account of them before the effects of polluted air on
human health can be clearly distinguished. Nonetheless, it is important for countries like Pakistan to establish national ambient air quality standards that take specific health and welfare effects into consideration. National standards and supporting regulations can satisfy a variety of purposes. These include: (a) protecting health and welfare in circumstances where long-term, low-level, irreversible impacts are suspected but not sufficiently quantified to permit the formulation of specific pollutant controls: (b) protecting people against locally high concentrations of hazardous pollutants emitted from a small number of isolated sources; (c) establishing limits on individual sources of pollution that have significant aggregate effects; (d) discouraging the migration of industry to regions with poor or non-existent emission restrictions; and (e) providing a vehicle for adopting energy and fuel savings policies. Badar Ghauri Manzar Salam M. I. Mirza SUPARCO Karachi, Pakistan
‘Rapid Assessment of Sources of Air, Water and Land Pollution, Publication No 62, World Health Organisation, Geneva.
Global environmental change at the Pacific Science Congress At the end of May 1991, Honolulu was the venue of the XVII Pacific Science Congress. It was the most recent of the major gatherings, every four years, of the Pacific Science Association, now over seventy years old. The meeting was attended by more than 1500 scientists from over 50 countries. The programme, with the overall theme ‘The Challenge of Change ‘, was built around six sections among which global environmental change in the Pacific figured prominently indeed.
Aside from ‘Global Environmental Change, Pacific Aspects’, the sections of the Pacific Science Congress were: ‘Population Health and Social Change’; ‘Science and Culture’; ‘Biological Diversity’; ‘Technologies for Development: Prospects for the 21st Century’; and ‘Dynamics of the
CHANGE
June 1992
Earth and the Heavens, the Pacific Arena’. I will try here to do some, albeit necessarily selective, justice to the extremely varied detailed reports and more general contributions to what we know or should know about past, ongoing and impending changes in geophysical, chemical and biolog-