Publications·October 31, 2012
This paper outlines the contribution of mobile sources to the urban air pollution problem in Pakistan, particularly in Karachi, and examines a series of options that address the significant cost imposed upon the economy and populace by ever-worsening air quality. The environmental health and economic analysis relies on primary data obtained from various ministries, agencies and institutions in Pakistan as well as from international development agencies. The analysis also uses several hundred reports and research studies from Pakistan and other countries. Quantification of health effects from environmental risk factors is grounded in commonly used methodologies that link health outcomes and exposure to pollution and other health risk factors, and the economic costs of these health effects are estimated using standard valuation techniques. The assessment of the benefits and costs of interventions to mitigate health effects and improve natural resource conditions is based on these same methodologies and valuation techniques, as well as on international evidence of intervention effectiveness, and, to the extent available, on data regarding the costs of interventions in Pakistan.
1 Urban-air-quality crisis in Pakistan
Pakistan is South Asia’s most urbanised country and its vehicle fleet has exploded from 0.8 million to nearly 5 million in just two decades—an average annual growth of >14 %
. Karachi, Lahore, Islamabad, Peshawar and Quetta all record annual fine-particle (PM₂․₅) levels far above WHO guidelines; Karachi’s 88 µg m⁻³ average (2006-09) is more than seven times the 10 µg m⁻³ recommended limit
. Road traffic dominates the urban mix: statistical correlations show PM₂․₅ most strongly aligned with CO and NO₂, classic traffic tracers, especially in winter inversion months when dispersion is poor
.
2 Data, methods and evidence gaps
The study draws on Pakistan’s nascent JICA-funded monitoring network (2007-10). Coverage is patchy—PM₂․₅ logged on only 17 % of days nationwide—yet it remains the richest dataset available
. Researchers combined:
Ambient monitoring of PM₂․₅, SO₂, NO₂, O₃ and CO at five cities.
Meteorology feeds (temperature, wind speed, visibility).
Principal-component analysis (PCA) to identify source groupings and seasonal shifts.
Health-impact functions (Ostro, Pope et al.) and economic valuation (value-of-statistical-life and human-capital approaches) to monetise morbidity and mortality.
Despite missing data, PCA consistently isolates a “Primary” factor (traffic & industrial combustion) explaining 22–43 % of variance and a “Secondary” photochemical factor (O₃, high temperatures) that dominates in summer months
.
3 Source apportionment – Karachi in focus
Karachi’s 2006-09 receptor and inventory analyses attribute:
24–28 % of PM₂․₅ to road vehicles, two-thirds from heavy-duty diesels and one-third from motorcycles & two-stroke rickshaws.
19–20 % to industry, with ferrous-metal plants leading.
8–14 % to open burning of solid waste, another pervasive urban issue.
4–5 % to household biomass burning.
Remaining shares split across power generation, secondary sulphates/nitrates (≈ 12–13 %) and natural / resuspended dust (≈ 23–24 %)
.
4 Health and economic burden
Model results indicate that Karachi’s ambient PM₂․₅ causes >9 000 premature deaths each year—12 % in children <5 y (acute lower-respiratory infections) and 88 % in adults (cardiopulmonary and lung-cancer deaths). City-wide, particulate pollution accounts for 20 % of ALRI mortality and 24 % of cardiopulmonary mortality among residents
. When monetised via willingness-to-pay, the losses approach US $1–1.5 billion annually, dwarfing the estimated costs of most control options.
5 Intervention menu and cost-benefit highlights
Measure Key prerequisites PM reduction potential Mid-point benefit-to-cost ratio*
Move diesel from 5 000 ppm → 500 ppm S (short term) and to 50 ppm S (medium term) Refinery upgrades, import standards Initial 500 ppm cut + low-sulphur secondary aerosol 1.1–1.8 for city-bound heavy diesels; still >1 for light diesels
Retrofit in-use diesels with DOCs (once 500 ppm fuel available) Inspection & maintenance (I/M), enforcement 20–30 % tail-pipe PM ≈1–1.3 for buses & trucks; <1 for minibuses/vans
Convert minibuses & delivery vans to CNG Secure gas supply, quality kits Virtually eliminate PM 1.2–1.7 (health gains outweigh kit costs)
Phase-out two-stroke rickshaws / motorcycles via four-stroke CNG or bans Credit for engine swap, enforcement >90 % PM + big noise drop ≈2 for rickshaws; 2.9–4.2 for motorcycles when fuel savings added
Low-sulphur (1 %) fuel-oil switch in city industries & power plants Fuel-oil import policy Direct PM + secondary sulphate cut Benefits (US $35–47 t⁻¹) approach price premium (US $50 t⁻¹); maximise by targeting urban users
* Mid-point of modelled range; discount rate = 10 %.
6 Governance and policy priorities
Strengthen continuous monitoring. Current data coverage is <50 % for most pollutants; improving QA/QC, staff training and instrument uptime is urgent
.
Adopt fuel-quality road-map. Lock-in refinery & import timelines for 500 ppm and 50 ppm diesel and for 1 % sulphur fuel-oil to unlock downstream technology.
Target high-use fleets. Prioritise DOC retrofits, CNG conversions and eventual DPF installation (post-50 ppm diesel) on urban heavy-duty vehicles that accrue the largest kilometre totals.
Manage CNG strategically. Reserve scarce gas for high-impact public transport and freight fleets rather than private cars with inefficient kits.
Accelerate two-stroke phase-out. Combine bans on new two-stroke sales with micro-credit, scrappage bonuses and mechanic-training programmes to retrofit or replace existing units.
Address solid-waste burning and construction dust—low-cost but politically neglected contributors—to capture quick air-quality wins.
7 Research gaps highlighted
Speciated PM and chemical source apportionment to distinguish traffic, industrial metal smelting and crustal dust fractions.
In-city dispersion modelling calibrated with continuous monitors to refine exposure maps.
Robust valuation of morbidity (hospital admissions, lost work-days) to complement mortality-centric analyses.
8 Key words
Karachi; PM₂․₅; diesel sulphur; diesel oxidation catalyst; CNG conversion; two-stroke phase-out; benefit-cost analysis; health impacts; monitoring gaps; urban transport emissions.