According to the World Bank report in 2016, air pollution has been identified as the deadliest type of pollution and the fourth leading cause of premature death worldwide. In recent years, major cities in Iran – including Tehran – have been seriously affected by air pollution, with a significant contribution (over 60%) from mobile sources. One of the causes of increased air pollution from mobile sources is the use of old and inefficient motor vehicles in urban areas, which worsens the already poor air quality due to outdated technology and high fuel consumption. The contribution of old transportation vehicles to air pollution in large and densely populated cities is undeniable, and modernizing or phasing them out is considered one of the effective solutions for improving urban air quality, which has been recognized as a reduction strategy in the air quality management systems of most countries.

Mostly, the combination of vehicles in traffic includes passenger cars, company buses, shuttle buses, minibuses, taxis, vans, trucks, and motorcycles, which in each group there are a considerable number of old vehicles that are still in use in cities. According to available statistics, around 6.5 million old vehicles are currently active in the urban transportation system in the country.

Considering the impact of urban transportation renovation on improving air quality, governments have taken action to reduce the harmful effects of this source of emissions by passing laws and implementing various plans to scrap and phase out old vehicles. In line with the implementation of Article 8 of the Clean Air Act (approved in 2017), scrapping old vehicles has once again become a priority for the government. The useful life of vehicles is determined based on the table below in the mentioned law, and vehicles that exceed the specified age must be phased out. In 2021, the regulations of Article 8 of the Clean Air Act were reviewed and the age limit was replaced with a mileage limit, requiring vehicles with higher mileage to undergo more frequent technical inspections. Vehicles over 15 years old must undergo two technical inspections per year, and if they do not receive a certificate, they are considered old vehicles. Currently, the age limit is being reconsidered in the draft of the Automotive Industry Organization Regulations, which has been presented to

Article 10 of the Automotive Industry Organization Law also pertains to the replacement of outdated vehicles, which prohibits the use of motor vehicles for transportation, cargo, and passengers in major cities after reaching a certain age. According to paragraph 3 of this law, in collaboration with relevant agencies, an executive regulation and necessary facilities must be developed for the replacement of outdated vehicles in public transportation with new vehicles.

According to international standards, the fuel consumption rate for a new passenger car with Euro 5 emission standards is approximately 11 liters per kilometer. However, after five years of operation (the age of vehicle obsolescence in European countries), fuel consumption increases by up to 40%. This is due to the malfunctioning of pollution control catalysts, which also leads to a significant increase in pollutant emissions. As for fuel-injected motorcycles with Euro 4 emission standards, after traveling 20,000 kilometers, the engine is considered worn out and the level of air pollutants also increases significantly. Table (1) compares the level of air pollutant emissions from new and worn out passenger cars and motorcycles.

Table No. (1): Comparison of the level of air pollutants emitted from new and old vehicles.

As shown in the above table, after reaching the age of aging, the level of air pollution will still increase significantly depending on the quality of fuel, suitable engine, and European technology.

However, if the age of obsolescence in Iran is considered to be 20 years for passenger cars and 8 years for motorcycles, regardless of fuel quality and manufacturing technology, the use of cars over 5 years without a catalytic converter for 15 years with this volume of traffic – which has not yet reached the legal age of obsolescence in Iran – imposes a significant pollution burden on the air quality of cities. It is worth noting that 14 million Euro 1 and 2 passenger cars without catalytic converters were produced between 2015-2003, which have not yet reached the age of obsolescence. Additionally, approximately 50% of road transport vehicles are also obsolete.

Renovation of motor vehicles in urban and highway transportation systems not only has an impact on air quality and public health, but also has economic benefits such as reducing repair and maintenance costs and saving fuel consumption. It also increases safety on city streets and highways. Despite the necessary legal infrastructure and the environmental, economic, and safety effects of this issue, so far, due to various reasons, the renovation of urban vehicles has not been successful. From the beginning of 1402 until now, only 29,000 vehicles out of 6.5 million old vehicles have been scrapped. Some of the existing challenges in this area include the following:

Prohibition of car import.

The entry of each vehicle is subject to the scrapping of a similar old car, which led to the scrapping of 160,000 cars in 1393 (2014). After the ban on car imports, this trend stopped. It is expected that this obstacle will be removed with the president’s order regarding the regulation of the car market.

Exemption of domestic car manufacturers from bankruptcy.

Despite the fact that according to Article 4 of the Waste Management Law approved in 2004, each producer is responsible for recycling their own products and also according to the executive regulations of the Public Transportation Development Law approved in 2007, car manufacturers are required to provide a certificate of disposal equivalent to 30% of their production, but in the past decade, car manufacturers have not taken any responsibility for their products at the end of their life cycle.

Inflation and major economic problems.

Inflation and increase in exchange rate, and as a result, decrease in people’s purchasing power can be one of the underlying factors in the increase in car prices, which leads to the tendency of investing in used cars.

Lack of financial resources.

According to the predictions, approximately 500 billion rials of credits are needed to provide affordable facilities for the renovation of transportation fleets, based on clauses 1 and 2 of article 8 of the Clean Air Law, which has not yet been allocated. Since the owners of old vehicles are from the weaker class of society and are affected by economic problems and inflation, it is not possible for them to replace their vehicles without financial support from the government.

“Removal of the age of senility based on the ruling of the Administrative Court of Justice.”

In accordance with the decision of the 453rd public session of the Administrative Court of Justice in 1399, the use of vehicles beyond the designated age limit set by Article 8 of the Clean Air Law was recognized as a violation of the rights of vehicle owners, resulting in a disruption of the process of scrapping.

People’s inclination towards personal trips.

The high cost of cars and the affordability of fuel, in the absence of a suitable urban transportation network, has led to people’s inclination towards personal trips, which ultimately results in an increase in daily fuel consumption and intensifies pollution.

It is worth mentioning that many of the challenges raised in the Law on Organizing the Automotive Industry, approved by the Islamic Consultative Assembly in 1401, have been resolved. The most important development in the matter is the change in the approach of the legislator from restrictive to incentive. In the aforementioned law, in addition to lifting the ban on car imports, all domestic car and motorcycle manufacturers are required to scrap their vehicles in order to obtain a numbering license, which greatly helps to solve the problem of outdated cars.

“Continued development of public transportation along with fuel price rationalization, is the key to reducing personal trips and consequently reducing air pollution from mobile sources.”