12 Jun 18

Air pollution in Tehran costs lives and money

According to a World Bank report published in April 2018, the air in Tehran (Iran) is amongst the most polluted in the world, leading to a higher incidence of respiratory illnesses and thousands of premature deaths each year. Replacing the most polluting vehicles could have a significant effect.

Climate and environment

A large part of the 17 million daily vehicular trips in Tehran are done in outdated vehicles. To make matters worse, topography and climate do not help. Tehran is located at a high altitude and is surrounded by a mountain range, which traps the polluted air. Temperature inversion, a phenomenon occurring during the winter months, prevents the pollutants from being diluted.

As a result, the World Bank study asserts that Tehran is one of the cities with the worst air pollution in the world, ranked 12th among 26 megacities and reaching ambient PM10 levels four times higher than the WHO's recommended threshold of 20 micrograms per cubic metre per year. Cities like Shanghai, Mumbai and Cairo perform even worse.

Health risks and economic costs

Air pollution is a major environmental risk factor for morbidity in Iran, including diseases such as asthma, lung cancer, ventricular hypertrophy, Alzheimer's and Parkinson's diseases and many more. There is also a high correlation with acute strokes and spontaneous abortions.

The economic costs associated with air pollution are estimated at $2.6 billion per year. Reducing air pollution concentration to levels comparable to those of New York would save the local economy around $1.6 billion in avoided economic costs each year.

Vehicle fleet

Of the 4.24 million vehicles in Tehran, 80% or 3.37 million are cars. In this category, 90% are passenger cars, 8% are pick-up trucks and a mere 2% taxis.

The second-largest category, accounting for 18% of total vehicles, are motorcycles (0.76 million units).

The smallest category is heavy-duty vehicles with a total number of 0.1 million vehicles or around 2% of total vehicles on the streets of Tehran.

Pollution share

Even though cars are by far the largest vehicle category, they only cause about 3% of the city's vehicle-related pollution. In turn, heavy-duty vehicles, which mostly run on diesel, contribute about 85%.

The disproportionate pollution share of heavy-duty vehicles is attributable in large part to the fleet's age. 30% of heavy-duty vehicles are more than 20 years old and nearly 60% of minibuses are over 20 years old. As such, most of the fleet consists of vehicles that have no particulate filters, selective catalytic reduction or diesel oxidation catalysts.

The way to cleaner air

In 2015, the government increased the emission standards for heavy-duty diesel vehicles to Euro 4. Additional measures are required, including rules and regulations regarding the age of the vehicle fleet, the introduction of low emission zones in large cities and improved public transport networks.

Prohibiting the production and import of carburettor petrol motorcycles would also help. Even though only 9% of passenger cars in Tehran are carburettor-equipped, they contribute to 51% of total emissions from passenger cars.

Image: air pollution over Tehran

Authored by: Benjamin Uyttebroeck