WHAT ARE ALMATY RESIDENTS BREATHING?

NO₂ AIR POLLUTION LEVELS IN 2023–2024

We tend to think that Almaty’s air turns “bad” only in winter as we rely on apps like AirVisual or IQAir, which mainly reflect PM2.5 concentrations. But even in summer, urban air remains far from clean.

Every day, over 600,000 vehicles move around Almaty, and they remain a major pollution source. The air contains hundreds of pollutants: PM₂.₅ and PM₁₀ particulates, sulfur dioxide (SO₂), carbon monoxide (CO), nitrogen dioxide (NO₂) and monoxide (NO), phenol, formaldehyde, ozone, cadmium, arsenic, lead, hexavalent chromium, nickel, benzopyrene, benzene, ethylbenzene, chlorobenzene, para-, meta-, ortho-xylene, cumene, and more.

Among the most toxic and common pollutants are NOx, the group of nitrogen oxides including NO₂ and NO, formed primarily by fuel combustion. Of these, NO₂ is especially dangerous as it generates secondary PM₂.₅ and ground-level ozone, which are key urban air pollutants.

The Almaty Air Initiative conducted the first Almaty study with two years (2023–2024) of NO₂ observations.

NO₂ and its health impacts

According to the WHO, long-term exposure to NO₂ is linked to reduced lung function, asthma exacerbations, and increased respiratory-related hospitalizations. Children, the elderly, and those with chronic respiratory conditions are especially vulnerable.

A 2022 global study indicates that approximately 16% of childhood asthma cases were triggered by elevated NO₂ levels. Chinese research also links prolonged NO₂ exposure to cancers, including oral cancer — showing a 7.2% increased risk after one year, rising to 11.5% after three years.

NO₂ also harms the brain and central nervous system, causing memory and attention deficits, reduced IQ in children, a higher risk of neurodegenerative diseases (like dementia), and triggering brain inflammation and oxidative stress that damage neurons and impair cognitive functions.

Sources of NO₂ in Almaty

The primary source of NO₂ emissions in Almaty is vehicle traffic. The Ministry of Internal Affairs of Kazakhstan reports that 31% of Almaty’s vehicle fleet is over 20 years old, not meeting modern environmental standards and often lacking catalytic converters required in many countries to reduce NOx and other toxic emissions.

The issue is worsened by a widely flawed technical inspection system, which for years has failed to properly verify vehicle emissions. As a result, thousands of vehicles with faulty exhaust systems continue to operate on the city’s roads.

Additional NO₂ sources include coal-fired power stations (CHP-2 and CHP-3), and smaller fuel-burning sources such as private homes, boiler plants, and bathhouses.

Unlike wintertime heating sources, vehicle emissions continue year-round, contributing most significantly to background NO₂ pollution, even in summer when other sources slow down.

NO₂: Official Kazhydromet Data for 2024

According to official data from Kazhydromet, Almaty recorded over 11,000 exceedances of the maximum permissible concentration (MPC) for NO₂ in 2024. This averages to roughly 900 exceedances per month, or about 30 times per day (Kazakhstan’s maximum one-hour MPC is 200 µg/m³; the daily limit is 40 µg/m³). This reveals chronic air pollution posing a health risk to the population.

In comparison, EU air quality directives allow a maximum of 18 exceedances per calendar year for the one-hour NO₂ limit, only under rare meteorological conditions. In Almaty, such high levels occur routinely.

Thus, official statistics confirm the chronic exceedance of safe NO₂ levels by international standards.

Almaty Air Initiative Study

To assess the scope of NO₂ pollution, we analyzed hourly NO₂ data from over 50 Almaty locations during 2023–2024. Using sensors installed in 2022 under the Asian Development Bank monitoring program for Almaty’s air quality, we:

• Reviewed seasonality and weekly pollution patterns
• Compared results with global standards
• Identified characteristic daily rhythms by district
• Proposed improvements for NO₂ monitoring and mitigation strategies

Exceeding WHO standards by 4 times or more

Compared to WHO guidelines, the annual average concentrations of NO₂ were 4.6 times higher in 2023 and 4.2 times higher in 2024 (see table below). We compared the indicators with WHO standards because Kazakhstan does not have an official annual limit for NO₂ concentration (only daily and monthly averages are used).

Table 1. Annual NO₂ values and comparison with WHO limit

NO₂ values are higher in winter than in summer

In winter, NO₂ concentrations are twice as high as in summer. In January and December, nitrogen dioxide levels reach peak values – nearly 130 μg/m³ in January 2023 and around 105 μg/m³ in December 2024, while in summer they drop to 35–45 μg/m³.

Seasonal dependence is clearly observed. There is a consistent decline in concentrations from January to July and an increase from October to December, indicating a strong seasonal influence on pollution levels.

The overall pattern and characteristic peaks remain similar in both 2023 and 2024, despite slight differences by month – this confirms the reliability of the data.

This situation is explained by several factors. In winter, the planetary boundary layer in Almaty becomes lower and temperature inversion often occurs – warm air above traps the cold air below, preventing pollutants from dispersing. At the same time, emissions from coal burning (in power plants and private homes) increase. In addition, wind ventilation in the valley weakens during this period, leading to stagnant air.

Like PM2.5, nitrogen dioxide shows winter peaks and summer declines, highlighting the deterioration of air quality during the cold season.

Zero clean days a year

Based on daily data, we can calculate the number of “clean” days (below 25 μg/m³) and “dirty” days (above 25 μg/m³). Even during the cleanest periods, average concentrations exceed WHO’s short-term recommendation (25 μg/m³ per day).

0 days in 2024 met the WHO guideline for NO₂ concentration (less than 25 μg/m³).

In 112 days, pollution levels were moderate (25–40 μg/m³), which is above WHO norms but considered acceptable by Kazakhstani standards.

Most days last year fell into the “orange” zone, air was dangerous for vulnerable groups. In 207 days, NO₂ levels exceeded 40 μg/m³, making the air unhealthy for sensitive groups (children, the elderly, asthmatics).

There were also 47 days when nitrogen dioxide concentrations exceeded 100 μg/m³, which is considered a very dangerous level of pollution for the entire population regardless of age or health status.

Dirty in winter, but also in summer:
Comparison of PM2.5 and NO₂

To compare, let’s examine the PM2.5 pollution calendar. The number of “clean” days, when PM2.5 concentrations were within WHO’s daily standard of 15 μg/m³, in 2024 in Almaty was much higher: 164 days. For NO₂ – only 16 days, highlighting the chronically high level of nitrogen dioxide and its serious underestimation as an environmental threat.

While PM2.5 pollution shows a strong seasonal pattern (sharp increase in winter and decline in summer), NO₂ levels remain high throughout the year, including summer months. This indicates a transport-related nature of NO₂ pollution, unlike the seasonal emissions from heating.

Dirtiest and cleanest periods

Dirtiest month: February 2024 – 109 μg/m³. The highest citywide NO₂ concentrations were recorded in mid-February. There were three days with critically high values dangerous to the health of all city residents. Based on the data, we can highlight the top 3 “dirtiest” NO₂ days in 2024:

• February 17 (163 μg/m³): the first major spike of the year, caused by cold weather, heating, and low atmospheric dispersion.
• February 19 (165 μg/m³): the citywide average, reflecting stable weather conditions conducive to pollutant buildup.
• February 20 (174 μg/m³): the absolute maximum average citywide NO₂ concentration – five times the WHO daily recommended limit.

Unfortunately, we lack sufficient analytical data to definitively conclude what exactly caused the sharp increase in NO₂ concentrations on those specific days last year.

Cleanest Month: May 2024 – 34.5 µg/m³
Changes in Daily Concentrations
At any time of year, NO₂ concentrations on weekdays are higher in the morning and evening. The dirtiest times of day are from 7:00 to 8:00 AM and from 8:00 to 9:00 PM. Pollution levels are influenced by the atmospheric boundary layer: it either “traps” dirty particles and gases near the ground (in the morning and evening), or it rises higher during the day, allowing polluted air to disperse.

How Concentrations Change Across Different Parts of the City

Pollution levels in Almaty are influenced by its topography and micrometeorology.

Based on daily pollution rhythms, two clusters have been identified in the city:

• A northern cluster (primarily monitoring points in Alatau, Zhetysu, and Turksib districts)
• A southern cluster (primarily in Bostandyk, Medeu, and Auezov districts)

In the southern cluster, daily fluctuations in concentrations are smaller, but overall pollution levels are slightly higher than in the northern one—likely due to less wind ventilation and the placement of sensors in relation to local sources.

• Cluster 1 (dark blue): Areas with moderate peaks in the morning and evening. Most NO₂ monitoring points in the northern districts (Alatau, Zhetysu, Turksib) fall into this cluster. Some points from this cluster are also found in other districts.
• Cluster 2 (light blue): Characterized by a less pronounced daytime drop in concentrations. Most of these points are located in the southern parts of the city, within Bostandyk, Medeu, and Auezov districts.

Their distribution across the city is shown below:

Why Do Air Pollutant Concentrations Follow This Pattern?

A 2022 study shows how the planetary boundary layer (PBL), which is represented by the black line in the graph, changes throughout the year and day in Almaty. These fluctuations directly affect pollutant concentrations.

In the morning and evening, when the PBL is at its lowest, surface air becomes “trapped” as pollutants accumulate due to the absence of vertical mixing. As the sun rises, the surface layer heats up, the PBL rises, and pollutants begin to disperse more actively, lowering ground-level concentrations. In the evening, the layer drops again and concentrations rise.

This daily “wave” is particularly noticeable when analyzing PM2.5 (see linked data), and a similar daily pattern is observed for nitrogen dioxide, as shown in the graphs above. This confirms that pollutant behavior is closely tied to PBL dynamics; they accumulate at night and in the morning when the layer is compressed, and disperse during the day as it rises.

In other words, daily fluctuations in air pollution are driven not only by emissions but also by atmospheric physics.

Average NO₂ Concentrations by Day of the Week

On weekdays, concentrations are slightly higher, especially in the morning and evening. On weekends, peaks are more smoothed out, especially during the warm season. Average levels across clusters are comparable, but Cluster 2 consistently shows values 1–2 µg/m³ higher on every day of the week.

Differences in concentrations between weekdays and weekends may be due to reduced traffic on weekends, increased coal use in bathhouses, and other factors.

To better understand this, it’s worth examining daily trends broken down by day of the week.

Daily Patterns by Day of the Week

Peak values on weekdays may be linked to increased morning and evening traffic activity. The relative decline in traffic during the middle of the day, combined with the rising PBL, explains the dip in the NO₂ concentration curve.

In our previous study, we showed that PM2.5 levels in Bostandyk and Medeu districts rose throughout the day, forming a characteristic “hill.” This is because PM2.5 is more inert, prone to accumulation, and may actively originate from local sources or be transported in the surface layer, especially during daytime. NO₂, on the other hand, is much more volatile and responds quickly to atmospheric changes, including dispersion.

Daily trends by clusters persist despite seasonal changes, though there is a significant drop in concentrations during the warmer months.

The Experience of Other Megacities

Cities like Seoul, Madrid, and London show that reducing nitrogen dioxide (NO₂) emissions is an achievable goal. But it requires systemic measures, many of which are also relevant to Almaty:

Recommendations for Reducing Pollution and Protecting Health:

• Expand and improve access to public transportation powered by gas and electricity. In Seoul, converting bus fleets to cleaner fuels was a key factor in reducing transportation-related emissions.
• Shift from coal to gas heating. Large-scale gasification of the residential sector in China significantly improved winter air quality. Almaty can follow suit by eliminating coal use in private homes and heating stations.
• Install filters on heating and industrial sources. Additional filtration systems help reduce nitrogen oxide emissions from large and small sources, from power plants to private households.
• Encourage walking and cycling, especially over short distances. Copenhagen and Amsterdam show how urban infrastructure improvements reduce car dependency and air pollution levels.
• Strengthen vehicle inspection and emission control. In countries with stronger institutions, annual vehicle inspections effectively prevent polluting cars from being driven in cities. Singapore and Japan also use smart monitoring systems to detect polluting vehicles in real-time.
• Introduce low emission zones (LEZ) in cities. London, Paris, and Milan have shown that LEZs effectively reduce NO₂ concentrations and encourage a shift to cleaner transport.

To Reduce NOx Health Impacts in Urban Settings, Follow These Guidelines:

• Avoid spending long periods near busy roads, especially during peak hours. This applies to walks, summer patios, and children’s playgrounds located next to traffic.
• Don’t exercise near roads. Choose parks, riverbanks, or areas near the foothills for physical activity and walks.
• Use mobile apps (e.g., IQAir or AirVisual) to track pollution levels and avoid outdoor exercise on days with high pollution.
• Ventilate your home during cleaner air periods: early morning, late evening, or after rain.
• If you live near a road, keep windows closed during rush hours.
• When in traffic, do not open windows as air pollution inside your car can be up to 40% higher, especially near “smoking” vehicles.
• Use air purifiers at home, especially in bedrooms and children’s rooms.
• Keep your car in good working order and get it inspected on time. This benefits not only your own health but also contributes to cleaner air for everyone.

These simple steps will not only help protect you and your family but also promote a culture where clean air is the norm, not the exception.

The Almaty Air Initiative Foundation expresses its gratitude to Clarity Movement, the Asian Development Bank, and Eco Almaty LLP for providing data on nitrogen dioxide.