Not the Quantity, but the Quality: How the Structure of Almaty’s Vehicle Fleet Affects Air Quality

On December 30, 2025, Almaty adopted the Atmospheric Air Protection Rules, which provide for further restrictions on motor vehicles. In response, the Almaty Air Initiative is conducting a study to assess the impact of the city’s vehicle fleet structure on air quality.

Motor vehicles are a key source of air pollution in Almaty, particularly in terms of nitrogen dioxide and fine particulate matter. In response to this challenge, the city is considering system-wide measures to reduce vehicle emissions, including the introduction of Low Emission Zones (LEZs), primarily targeting vehicles in emission classes 0-4 – the segment of the vehicle fleet with the highest pollutant emissions. 

This study assesses the contribution of motor vehicles to air pollution in Almaty, focusing on fine particles (PM2.5) and nitrogen oxides. The paper analyzes the structure of the city’s vehicle fleet, the actual distribution of traffic flows, and how vehicles of different emission classes contribute to air pollution. The study also models the potential impact of introducing low-emission zones. The objective of the study is to estimate the potential environmental impact of restrictions on the city’s most polluting vehicles.

Nitrogen Dioxide Pollution

Motor traffic remains a key source of air pollution in Almaty. More than 600,000 vehicles operate in the city daily, making transport the primary contributor to nitrogen dioxide (NO2) emissions. According to a 2024 study by the Almaty Air Initiative, average annual NO2 concentrations in the city exceed WHO (World Health Organization) recommendations:

• by a factor of 6.1 in 2023
• by a factor of 5.9 in 2024

These levels of exposure document adverse health effects. According to the WHO, long-term exposure to elevated NO2 concentration causes decreased lung function, exacerbates asthma, and increases the incidence of hospitalizations related to respiratory diseases.

Traffic-Related Air Pollution (TRAP) and Its Impact on Health

Air quality near roads differs significantly from background levels. This is why scientific literature uses a separate term for traffic-related air pollution: TRAP (Traffic-related air pollution). TRAP is a mixture of gases and particles formed directly in road corridors: nitrogen dioxide (NO2), PM2.5, PM10, soot, volatile organic compounds, and other toxic components. Pollution is generated not only by engine operation but also by tire wear, brake wear, and road surface abrasions. A significant portion of the emissions are concentrated at breathing height, which increases their harmful effects. International studies show a consistent link between TRAP, particularly high NO2 concentrations and proximity to roads, and:

• increased risk of developing asthma in adults and children
• increased risk of cardiovascular disease
• increased overall mortality
• increased risk of lung cancer

According to WHO estimates, approximately 16% of childhood asthma cases in cities are directly related to exposure to NO2 – a major transport pollutant. 

Residents of areas near heavy traffic are at greatest risk. Living within 100-500 meters of busy roads carries an increased risk of childhood asthma, pregnancy complications, and long-term cognitive effects associated with chronic exposure to NO2 and PM2.5.

A particular feature of traffic pollution is its increased impact on road users. A study of fine particle concentrations on roads found that drivers and passengers stuck in traffic with the open windows breathe air seven times more polluted than pedestrians standing at intersections. Furthermore, air pollution inside a car stuck in traffic is 40% higher than under free-flowing traffic conditions.

The scale of the impact of transport pollution is often underestimated. In several countries, including Australia, mortality associated with vehicle emissions significantly exceeds the number of fatalities in road accidents. Globally, transport emissions are associated with approximately 246,000 premature deaths annually.

Structure of Almaty’s Vehicle Fleet

Over the past year, Almaty has become one of the fastest-growing cities in the region in terms of vehicle ownership. According to the Ministry of Internal Affairs of the Republic of Kazakhstan, as of September 2025, 797,000 vehicles were registered in the city, which is almost 150,000 more than the year before (647,000). Of these, 714,000 were passenger cars.

The number of electric vehicles is also growing rapidly: their number has almost doubled in one year, from 6,410 to 12,401. However, their share of the city’s vehicle fleet remains small, at around 2%. Hybrids* account for 4% of the vehicle fleet.

*Hybrids are cars with multiple fuel types: gasoline, gas and electricity.

Vehicle’s Age is a Key Factor in Air Quality

The structure of the city’s registered vehicle fleet reveals a serious problem:

• 25% of cars are between 10 and 20 years old
• 30% are over 20 years old 

In the Almaty region, the situation is even worse: 57% of cars are over 20 years old.

Age is an indirect indicator of the environmental class of a vehicle – the older the car, the lower its environmental class, and the more emissions it produces.

What’s Really Happening on the Roads?

To get a realistic picture of traffic, analysts from Almaty Air Initiative and Sergek Group studied traffic flows for a year – from August 1, 2024, to August 1, 2025. A total of 1.8 million unique vehicles were analyzed.

Structure by type of vehicle

• 90% – passenger cars
• 8% – trucks
• 2% – buses

Age structure by vehicle flow

• 33% – manufactured in 2021 or newer
• 18% – 2016 – 2020 
• 16% – 2011 – 2015 
• 11% – 2006 – 2010 
• 22% – were made before 2005

In fact, every third car on the city streets (33%) is older than 15 years (made before 2010). 

Low Emission Zone (LEZ) Pilot Analysis Results

To assess the potential impact of the Low Emission Zone, a block of the following streets was studied: Kabanbay Batyr – Dostyk – Abay – Zheltoksan.
Period: October 1–29, 2025.

On average, approximately 82,000 unique vehicles pass through the zone daily.

Structure by type of vehicle:

• 95% – passenger cars
• 4% – trucks
• <1% – buses

Age structure:

• 63% – under 10 years old.
• 37% – eco-class 0-4.

Thus, cars of eco-class 5 accounts for 63% of the total mileage in the block, while vehicles in eco-classes 0-4 make up only 37%:

To assess the contribution of various vehicle fleet segments to air pollution, vehicle emissions within the studied area were calculated by vehicle type and emission class. The calculations were performed using emission factors from the COPERT methodology, widely used in European and international vehicle emission inventories, together with total vehicle mileage data. 

Although vehicles in emission classes 0-4 account for only 37% of the total mileage, they account for 79% of NOx emissions and 78% of PM emissions from vehicles within the studied area. This confirms the general pattern established by international agencies: older and technically obsolete engines emit significantly more NOx and fine particles per kilometer traveled.

When considering the contribution by transport type, with a share of 3% of the total mileage, trucks account for 32% of NOx emissions and 64% of PM, highlighting their disproportionately high contribution to vehicle pollution. 

Hypothetical Scenario for Vehicle Fleet Modernization

Modeling has shown that if all vehicles in emission classes 0–4 were upgraded to Euro-5, while maintaining the current mileage within the pilot zone, a significant reduction in transport emissions would be achieved:

•  a 67% reduction in NOx emissions
•  a 62% reduction in PM emissions

Taking a more targeted approach, even modernization of trucks only yields a significant impact due to their high disproportionate pollutant contribution. With a relatively small share of miles traveled, emission reductions can go up to 15% of NOx emissions and 50% of PM emissions.

However, the greatest potential for reducing vehicle pollution lies not so much in fleet renewal as in the transition to eco-friendly public transport. In addition to modernizing trucks, a complete transition of passengers from private cars to electric-powered public transport simultaneously reduces both the total number of kilometers traveled and pollution, achieving an 83% reduction in NOx emissions and an 86% reduction in PM emissions.

The assessment reflects the total emissions of vehicles within the studied area and illustrates the potential impact of upgrading the most polluting segment of the vehicle fleet.

Why is This Important?

• Air pollution from transport is one of the main reasons for elevated NO2 levels in Almaty.
• According to the WHO, NO2 and fine particulate matter (PM2.5) are associated with an increase in asthma in children, worsening of cardiovascular diseases and an increased risk of overall mortality.

International experience shows that vehicle fleet renewal and the introduction of Low Emission Zones (LEZs) are effective tools for reducing transport pollution. Such measures have been implemented in London, Paris, Berlin, Madrid, and more than 300 cities in Europe and Asia.

A case in point is Bradford (UK), where the LEZ was used as a tool for accelerated transport modernization. Between 2022 and 2024:

• 87% of taxis switched to stricter environmental standards,
• 370 city buses were modernized,
• 33 electric buses were purchased.

This case demonstrates that the LEZ can function not as a prohibitive measure, but as an economic and regulatory incentive, accelerating fleet renewal and the development of environmentally friendly public transport without major social disruption.

The most sustainable long-term effect is achieved by reducing the use of private cars and developing high-quality, environmentally friendly public transport. The transition from private to public transport simultaneously reduces emissions, road congestion, and the impact of transport-related air pollution (TRAP) on the population. In a highly motorized context, fleet renewal and the introduction of LEZs are essential transitional measures that can achieve short-term reductions in harmful impacts.

The results of the study reveal a critical imbalance: the bulk of toxic air pollution in Almaty is generated not by the overall flow of vehicles, but by a specific segment of the fleet. Vehicles in emission classes 0–4, while accounting for only 39% of the total mileage, are responsible for 79% of nitrogen oxide emissions, creating a “traffic trap” (TRAP), where city residents are exposed to NO2 and PM2.5 concentrations that are several times above WHO recommendations.

Modeling shows that targeted interventions on this segment of the vehicle fleet — through modernization, replacement, or operating restrictions — can reduce overall vehicle emissions in the city by up to half. Reducing NO2 and PM2.5 emissions is directly linked to reduced public health risks, particularly for respiratory and cardiovascular diseases.

This very effect was observed in the aforementioned Bradford (UK) example: just one year after the launch of the Low Emission Zone (LEZ), resulting in 700 fewer doctor visits per month: 600 for respiratory diseases and 134 for cardiovascular diseases. This experience confirms that low emission zones can deliver rapid and measurable health benefits, not just reduced emissions.

Therefore, low-emission zones are an effective tool for comprehensively addressing transport pollution: firstly, they reduce concentrations of toxic gases and fine particles by restricting the most polluting transport; secondly, they stimulate fleet renewal, accelerating the transition to electric vehicles and low-emission transport without direct bans; and thirdly, they provide a measurable effect on public health. 

Conclusion

The study shows that the decisive factor in air pollution in Almaty is not the total number of vehicles, but the quality of the vehicle fleet. Approximately 49% of vehicles belonging to older emission classes contribute disproportionately to nitrogen oxide (NOx) and fine particulate matter (PM2.5) emissions.

In the long term, achieving safe air quality is impossible without developing high-quality public transportation and reducing the city’s reliance on private cars. However, given the high level of motorization, transitional measures are needed to reduce the impact of the most polluting segment of the vehicle fleet. 

Such measures may include low-emission zones (LEZs) and other tools aimed at upgrading, replacing, or restricting the use of vehicles with low emission ratings. A targeted approach to this segment allows for rapid and significant reductions in the impact of transport pollution without applying blanket restrictions to the entire vehicle population. 

Scenario analysis shows that the gradual replacement or decommissioning of the most polluting vehicles could reduce NOx and PM2.5 emissions by more than 60%. Therefore, regulation focused on the environmental performance of transport is a justified and effective step in bringing air quality in Almaty to levels safe for public health.