What Was Air Quality Like in Almaty in 2025?

PM2.5 Monitoring Results: Key Figures

2025 was another challenging year for Almaty residents in terms of air quality. We recorded a 30% increase in pollutant concentrations compared with the previous year.

The main sources of air pollution in Almaty have not changed significantly in recent years. Much of the year-to-year variation can be explained by weather conditions. In 2024, a windier winter and a rainy summer acted as a natural filter, bringing the annual average PM2.5 concentration down to 24.1 µg/m³. In 2025, precipitation was noticeably lower: a dry summer and frequent periods of calm winds during winter reduced pollutant dispersion and contributed to their accumulation. As a result, the number of polluted days increased, along with the annual average PM2.5 concentration.

Urban smog is a mixture of different pollutants. In addition to PM2.5 and PM10 particulate matter, the air contains nitrogen dioxide (NO₂), sulfur dioxide (SO₂), carbon monoxide (CO), ozone (O₃), and other substances. In this report, we focus on PM2.5 as the most harmful, representative, and readily available indicator of air pollution.

Key Indicators:

• Annual average PM2.5 concentration: 31.2 µg/m³, or 6.3 times the WHO guideline.
• Worsening trend: Air pollution increased by 30% compared with 2024 (24.1 µg/m³).
• Individual health burden: The average city resident was exposed to a toxic pollution burden equivalent to smoking 518 cigarettes over the year. In Turksib District, air pollution exposure was comparable to smoking 776 cigarettes per resident.
• Shortage of clean-air days: The number of “safe” days (according to WHO guidelines) decreased by 16 compared with the previous year, from 164 days in 2024 to 148 days in 2025. This now represents only 40% of the year, compared with approximately 45% the year before.
• The “trapping” effect: The nighttime mountain breeze does not clean the city’s air. Instead, it effectively pushes smog into lower-lying districts, where it becomes trapped due to temperature inversions.

Extremes and Contrasts:

• Annual variation: Air pollution levels differed by a factor of 29 between the cleanest day (October 1) and the most polluted day (December 7). The city experiences extreme fluctuations in air quality.
• Seasonal gap: The most polluted month (December, 62.4 µg/m³) had PM2.5 concentrations 5.5 times higher than the cleanest month (May, 11.3 µg/m³). On average, PM2.5 concentrations during winter months are five times higher than during summer months.
• Geographic inequality: Turksib District (46.8 µg/m³) was 2.1 times more polluted than Bostandyk District (22.1 µg/m³). This confirms that residents of the city’s lower-lying areas face a disproportionately high pollution burden.

Air Pollution Exposure in Cigarette Equivalents

To make air quality monitoring data easier to understand, we use an internationally recognized approach that converts PM2.5 concentrations into “cigarette equivalents.” Although inhaling smog is not identical to smoking cigarettes in terms of chemical composition, it creates a comparable burden on the respiratory system, resembling continuous passive smoking.

For reference: This approach is based on estimates developed by the Berkeley Earth research group and epidemiological evidence on the health effects of PM2.5. In simplified terms, an annual average PM2.5 concentration of approximately 22 µg/m³ can be considered comparable, in terms of health risk, to smoking one cigarette per day. (Source)

Citywide estimate: In 2025, the average Almaty resident effectively “smoked” 518 cigarettes — approximately 26 packs — or nearly 1.42 cigarettes per day.

Health Risks by District:

Air pollution is unevenly distributed across the city, creating different levels of long-term health risks depending on where people live:

It is important to note that, unlike active smoking, exposure to smog is continuous and involuntary. It affects the most vulnerable groups — children and the elderly — 24 hours a day, even indoors in buildings without air purification systems.

Chapter 1. Air Pollution Trends and Patterns in 2025

The annual average PM2.5 concentration in Almaty in 2025 was 31.2 µg/m³, which is 6.3 times higher than the World Health Organization (WHO) guideline of 5 µg/m³. Compared with 2024 (24.1 µg/m³), air quality deteriorated by 30%.

For reference: PM2.5 refers to fine particulate matter in the air with a diameter of 2.5 micrometers or less. These particles are so small that they can penetrate deep into the lungs and even enter the bloodstream, making them harmful to human health. High concentrations of PM2.5 in the air can cause respiratory and cardiovascular diseases, particularly among children, older adults, and people with chronic health conditions.

The annual pollution profile shows a strong seasonal pattern and substantial fluctuations in PM2.5 concentrations.

 

Winter: Characterized by extreme pollution peaks that consistently exceed Kazakhstan’s national daily average maximum permissible concentration (MPC) of 35 µg/m³. High variability and the accumulation of particulate matter near the ground create critical short-term health risks.

Spring and Summer: Pollution levels stabilize and decrease. Most readings fall within the “good” and “moderate” air quality categories, while exceedances of the MPC occur only occasionally. Nevertheless, even during favorable months, concentrations exceed the WHO daily guideline of 15 µg/m³.

Transitional Seasons: Characterized by increased variability. The alternation between clean-air days and sharp pollution spikes reflects the city’s high sensitivity to meteorological conditions and solid-fuel combustion.

Monthly Average Concentrations: 2024 vs. 2025

From January to September, Almaty operated a network of Clarity sensors installed under an Asian Development Bank program, allowing us to make a direct comparison with 2024. Comparing equivalent periods confirms the worsening air pollution trend in 2025:

Critical Increase: During the first two months of 2025, monthly average PM2.5 concentrations reached 57.5 µg/m³ in January and 61.6 µg/m³ in February, representing increases of 14% and 26%, respectively, compared with the same months in 2024.

However, March showed an improvement, with concentrations falling to 28.4 µg/m³ compared with 33.2 µg/m³ in 2024. The period from April to September traditionally remains the cleanest part of the year. Concentrations ranged from 11.3 to 15.4 µg/m³, close to the WHO daily guideline of 15 µg/m³.

Air quality follows a pronounced seasonal pattern. Even when comparing only the first nine months of the year, during which Clarity sensors had been operating for three consecutive years, 2025 showed higher pollution levels, primarily driven by winter concentrations.

Regarding the final quarter of 2025 (October–December), it is important to note that additional data sources from 170 new sensors in the Almaty Air Initiative network were included in the analysis starting in October.

The new sensors captured a sharp increase in the monthly average concentration to 36.3 µg/m³, compared with 23.1 µg/m³ in 2024. This increase was associated with the start of the heating season (October 8–10) and colder weather, which reduced pollutant dispersion. Under these conditions, emissions accumulated in the near-surface atmospheric layer, establishing elevated background pollution levels that persisted throughout the winter.

In November and December, concentrations reached critical levels of 54.4 µg/m³ and 62.4 µg/m³, respectively.

Number of Days Exceeding the WHO Daily Guideline

In 2025, Almaty experienced a significant reduction in the number of days with safe air quality.

Over the past year, Almaty recorded 148 days (40.5% of the year) when the daily average PM2.5 concentration met the WHO guideline of 5 µg/m³ — 16 days (10%) fewer than in 2024.

During the remaining 217 days (almost 60% of the year), pollutant concentrations exceeded the guidelines to varying degrees. Of these, 124 days also exceeded Kazakhstan’s less stringent national maximum permissible concentration (MPC) of 35 µg/m³:

• 15–35 µg/m³: 93 days (25.5%). During these periods, PM2.5 concentrations exceeded WHO guidelines but formally remained within Kazakhstan’s national MPC of 35 µg/m³.
• 35–70 µg/m³ (1–2 times the MPC): 89 days (24.4%).
• 70–140 µg/m³ (2–4 times the MPC): 34 days (9.3%).
• Above 140 µg/m³ (more than 4 times the MPC): 1 day. The most polluted day was December 7, when the citywide daily average PM2.5 concentration reached 145.1 µg/m³.

• • In January, February, and December, virtually no days with clean air were recorded.
  • July 2025 was unusual: the number of days exceeding the WHO guideline increased to 7, compared with none in 2024. The average pollution level in July was 24% higher than in June.

  One possible contributing factor was drier weather compared with the previous year. In the absence of rain and with weak winds, dust and vehicle exhaust emissions can accumulate in the air even during summer, challenging the common perception that summer air is clean.

  The overall statistics confirm that air pollution in Almaty is a structural problem. For more than 60% of the year, the city experiences air pollution levels that exceed international air quality guidelines.

  CHAPTER 2. The City’s Rhythms: Daily and Seasonal Patterns

  Daily Pollution Profiles by Season

  The distribution of PM2.5 concentrations throughout the day shows a clear dependence on the season:

• • Winter is the most critical season, marked by a persistently high pollution background. The average PM2.5 concentration in winter is 61.1 µg/m³, which is almost 1.8 times higher than Kazakhstan’s daily average maximum permissible concentration (MPC). Even the average morning minimum (05:00–08:00) remains at 43–45 µg/m³, meaning concentrations exceed the national standard throughout the entire day. Peak levels are recorded between 19:00 and 21:00 (above 80 µg/m³), which can be explained by the lowering of the planetary boundary layer (temperature inversion), combined with the evening traffic peak and peak нагрузки on autonomous heating systems.
  • Autumn shows a pattern similar to winter, but with lower amplitudes before the start of the heating season. The average PM2.5 concentration in autumn is 43 µg/m³, which also exceeds Kazakhstan’s MPC. During the daytime plateau (03:00–16:00), concentrations fluctuate around 30–40 µg/m³, hovering around the Kazakhstan MPC threshold (35 µg/m³). The evening spike (after 16:00) causes concentrations to double by around 20:00, reaching 66–67 µg/m³.
  • Spring and summer are the cleanest periods, due to better mixing of air masses and the absence of heating-related emissions. Summer is characterized by the lowest and most stable PM2.5 concentrations: the average level is 12.7 µg/m³, and for nearly 24 hours a day concentrations remain in the WHO “green zone” (below 15 µg/m³). A slight increase is observed only around 20:00.
  • In spring, the pollution pattern generally mirrors summer, but with somewhat higher concentrations. The average PM2.5 concentration in spring is 18.6 µg/m³, and daily levels typically range between 15 and 25 µg/m³. The evening peak remains, reaching around 26 µg/m³, but its amplitude is significantly lower than in autumn and winter.

  Impact of the Heating Season: October 10 as the Turning Point

  A comparison of data before and after the official start of the heating season (based on the AirGradient sensor network) revealed a systemic transformation in air quality across the city.

  To clearly illustrate these changes, the map shows the locations of AirGradient stations in Almaty and nearby settlements in Almaty Region. The center of each marker represents air quality before the heating season (from September 1 to October 10), while the outer ring shows conditions after the start of the heating season (from October 10 to December 31). The size of each marker is proportional to the average daily concentration (from smaller to larger).

• • Systemic Shift: Almost no monitoring locations on the city map retained a uniform color. The widespread appearance of bright red and purple rings around green and yellow centers indicates a sharp increase in PM2.5 concentrations following the start of the heating season.
  • Geographic Patterns: The most pronounced differences (wide, contrasting rings) are observed in the northern and northwestern parts of the city. These are areas where emissions from individual household heating systems combine with the background impact of CHP-2 and CHP-3, creating zones of extreme environmental risk.
  • Relatively Stable Areas: Only the foothill districts (the upper parts of Medeu and Bostandyk Districts) maintained relative stability, where evening mountain breezes partially offset the increase in emissions.

  District-Level Analysis

  A quantitative analysis across Almaty’s districts confirms the patterns shown on the map. The transition to the heating season led to increased air pollution in every district without exception, particularly in the northern part of the city. However, the magnitude of this increase varied considerably.

  

In the city’s lower-lying districts (Alatau, Turksib, and Zhetysu), a severalfold increase in toxic pollution exposure was recorded. Following the start of the heating season on October 10, daily average PM2.5 concentrations in these areas consistently remained within the range considered harmful to health (70–140 µg/m³), exceeding the WHO daily guideline (15 µg/m³) by 4–9 times.

Chapter 3. Geography of Air Pollution: Spatial Analysis

The clearest pattern emerges when moving from the foothill districts toward the lower-lying parts of the city. The map showing the spatial distribution of average PM2.5 concentrations in October–November 2025 reveals pronounced variations in air pollution levels across Almaty, driven by both natural geographic conditions and human activities.

Southern Zone (Foothills): This area has the most favorable air quality conditions. The elevated terrain and mountain breezes provide effective air circulation, which, combined with the absence of major industrial facilities and heating plants, helps keep pollutant concentrations relatively low.

As we move toward the central and northern districts, pollutant concentrations increase steadily. Central Almaty forms a zone of moderate pollution, reflecting high traffic density, densely built-up residential areas, and intensive urban activity.

The most unfavorable conditions are recorded in the northern and northwestern districts, where the highest concentration of monitoring locations with elevated average PM2.5 levels is observed. The critical situation in these districts is driven not only by local emission sources (private households and industrial facilities) but also by the specific atmospheric dynamics of the Almaty Basin.

During evening and nighttime hours, a distinctive meteorological pattern develops:

• Mountain–Valley Circulation: Cooled air from the mountains (nighttime mountain breeze) moves from south to north, effectively pushing pollutants accumulated during the day from the upper and central parts of the city into lower-lying areas.
• Atmospheric Trapping: As this airflow reaches the central part of the city, it slows down. Due to limited ventilation and temperature inversions, harmful pollutants become trapped in the near-surface atmospheric layer.
• Cumulative Effect: Intensive nighttime emissions from local households add to the smog transported from the city center. As a result, PM2.5 concentrations in northern districts not only fail to decrease at night but continue to rise, creating areas of persistent pollution exposure.

During autumn and winter, pollutants accumulate in the near-surface atmospheric layer and disperse very slowly, resulting in consistently high concentrations even in the absence of extreme emission events.

 

The clustering map of daily average PM2.5 concentrations confirms this pattern. Two distinct spatial clusters can be clearly identified across the city, differing in both pollution levels and geographic location. The boundary between these clusters largely follows the city’s natural slope from south to north.

The most polluted cluster (red markers) is predominantly concentrated in the northern and northwestern parts of the city, below Raimbek Avenue, including Turksib, Alatau, and Zhetysu Districts. This cluster is characterized by consistently high daily average PM2.5 concentrations, with an average sensor reading of 65.3 µg/m³, almost twice the level recorded in the relatively cleaner cluster.

The relatively cleaner areas (green markers) are located in the southern foothill zone of the city, above Al-Farabi Avenue, including Bostandyk and Medeu Districts. These areas have significantly lower pollution levels, with average daily PM2.5 concentrations of 32.3 µg/m³. The more favorable conditions in southern Almaty are associated with its foothill terrain, better air circulation, and a lower concentration of local emission sources.

Thus, the distribution of air pollution in Almaty is largely determined not by isolated events but by the city’s terrain, urban development patterns, and airflow dynamics. The map confirms that air pollution in Almaty has a pronounced spatial pattern and is not evenly distributed across the city. The difference between southern and northern districts persists even when data are averaged over several months, indicating structural causes of pollution rather than isolated episodes.

District Ranking by PM2.5 Concentrations

Quantitative data confirm that the pollution gap between the city’s upper and lower areas is approximately twofold.

Relatively Lower Pollution Levels:

• Bostandyk District: 22.1 µg/m³ (the lowest concentration in the city)
• Auezov / Medeu Districts: 25.8 µg/m³
• Nauryzbay District: 27.1 µg/m³

Higher-Risk Areas:

• Turksib District: 46.8 µg/m³
• Zhetysu District: 37.9 µg/m³
• Alatau District: 37.7 µg/m³
• Almaly District: 30.9 µg/m³

The heatmap below provides a detailed view of how the pollution burden was distributed across Almaty’s districts throughout 2025.

The figure clearly shows that Turksib, Zhetysu, and Alatau Districts remain the areas most affected by elevated pollution concentrations throughout the year. They are the first to enter the high-pollution categories (red, purple, and burgundy segments) and the last to emerge from them.

While the city’s lower-lying districts record concentrations exceeding 140 µg/m³, the southern parts of Almaty (Bostandyk and Medeu Districts) often remain within the red or even yellow categories on the same days. The terrain and proximity to the mountains provide southern Almaty with brief periods of improved air quality that are virtually absent in the northern part of the city.

Chapter 4. Extreme Pollution Days

The Cleanest and Most Polluted Days of 2025

Throughout 2025, Almaty experienced an unprecedented difference between its minimum and maximum daily average PM2.5 concentrations, with a 29-fold variation. This clearly demonstrates how strongly air quality depends on seasonal factors, meteorological conditions, and human activities.

Top 10 Cleanest Days:

The day with the most favorable air quality was October 1, 2025. On that day, the daily average PM2.5 concentration was 5.0 µg/m³, meeting even the strictest WHO annual average guideline.

However, the analysis shows that this did not represent the city’s typical background pollution level. The improvement in air quality coincided with unusual weather conditions. On October 1, Almaty experienced a sharp change in weather: nighttime temperatures ranged from +3°C to +8°C, while daytime temperatures were between +5°C and +10°C. Wind speeds reached 9–14 m/s, with gusts of 15–29 m/s. Rainfall was also recorded, along with snowfall in mountainous areas.

Apart from October 1, the top 10 cleanest days of 2025 were predominantly in spring and summer:

• September 23 — 5.7 µg/m³
• May 26 — 6.2 µg/m³
• May 11 — 6.6 µg/m³
• July 10 — 6.7 µg/m³
• May 12 — 6.8 µg/m³
• January 23 — 7.2 µg/m³
• August 18 — 7.4 µg/m³
• July 11 — 7.7 µg/m³
• May 19 — 8.1 µg/m³

Even on these relatively favorable days, localized exceedances were recorded in certain districts. However, they did not significantly affect the citywide average.

Top 10 Most Polluted Days:

The most polluted day of the year was December 7, 2025.

December was the period of the most severe pollution burden, reaching its peak during the first ten days of the month. The daily average PM2.5 concentration reached 145.1 µg/m³.

This was 9.7 times higher than the WHO daily guideline (15 µg/m³) and 4.1 times higher than Kazakhstan’s national maximum permissible concentration (MPC) of 35 µg/m³.

At the same time, peak hourly average concentrations in certain districts reached an extreme 493 µg/m³. Such pollution levels pose a direct threat to public health.

The day was characterized by stable weather conditions with no precipitation, partly cloudy skies, and weak easterly winds (3–8 m/s). Nighttime temperatures ranged from 0°C to −2°C, while daytime temperatures reached +6°C to +8°C.

These conditions prevented pollutant dispersion, leading to their accumulation and a sharp increase in PM2.5 concentrations.

Toward the end of the day, fog and precipitation began to develop, indicating high humidity and weak vertical mixing of air masses. As a result, pollutants accumulated over the preceding hours were not dispersed, and concentrations reached extreme levels.

Overall, the top 10 most polluted days of 2025 occurred exclusively during winter:

• January 14 — 125 µg/m³
• January 15 — 121.3 µg/m³
• January 12 — 117.7 µg/m³
• February 7 — 104.9 µg/m³
• December 3 — 104.1 µg/m³
• February 9 — 104 µg/m³
• January 27 — 98.7 µg/m³
• February 8 — 97.9 µg/m³
• December 29 — 97.6 µg/m³

All these days were characterized by simultaneously elevated citywide average concentrations and extreme localized peaks, indicating a combination of increased emissions and limited pollutant dispersion.

Air Pollution by Day of the Week

Extreme pollution episodes reflect the most unfavorable conditions but do not reveal regular behavioral and social patterns associated with air pollution.

An analysis of daily average PM2.5 concentrations by day of the week identified clear patterns that persist independently of isolated weather anomalies.

Sunday — The Weekly Pollution Peak: Sunday is the most polluted day of the week, with an annual average PM2.5 concentration of 37.3 µg/m³. Moreover, the highest daily average concentration of the entire year — 145.1 µg/m³ — was recorded on Sunday, December 7, indicating that some of the most severe smog episodes occur toward the end of the week.

Saturday — The Beginning of the Increase: Pollution levels begin to rise on Saturdays, reaching an average of 32.7 µg/m³, already exceeding the average concentrations recorded on weekdays.

Monday — The Lingering Weekend Effect: Monday maintains a relatively high average concentration of 31.7 µg/m³, potentially reflecting pollutants that accumulated over the weekend and had not fully dispersed by the beginning of the working week.

Wednesday and “Clean” Thursday: Pollution levels reach a local minimum in the middle of the week. Wednesday records the lowest average concentration at 27.2 µg/m³, followed closely by Thursday at 28 µg/m³, living up to its popular reputation as a relatively clean day. The difference between the cleanest day, Wednesday, and the most polluted day, Sunday, exceeds 37%.

Tuesday and Friday: These days show moderate average concentrations of 30.4 µg/m³. However, a significant pollution spike of up to 124 µg/m³ was recorded on a Tuesday, indicating that severe but less frequent pollution episodes can also occur on weekdays.

Contrary to common expectations, weekends have higher average PM2.5 concentrations than weekdays (35.6 µg/m³ versus 29.9 µg/m³, respectively). Daily pollution patterns clearly show that this difference emerges in the evening: on weekends, concentrations rise sharply after 16:00, reaching an average peak of approximately 57 µg/m³ by 20:00.

This pattern challenges the widespread assumption that weekday traffic is the primary driver of urban smog. The data show that air quality remains consistently poor on weekends — particularly on Sundays — and sometimes deteriorates even further.

These findings suggest that attention should shift from vehicle traffic alone to a broader combination of factors. Private households burning coal and energy generation facilities likely continue to play a significant role, with heating demand remaining high or even increasing on weekends when residents spend more time at home. Thus, the air pollution problem extends far beyond traffic congestion.

What Drives Air Pollution: Sources and Conditions

Extreme air pollution levels in Almaty are not caused by isolated emissions but by a combination of continuous emission sources and weather conditions. During winter, the city regularly experiences periods of pollutant accumulation: emissions increase while conditions for their dispersion deteriorate sharply.

The beginning of the heating season marks a critical turning point in pollution levels. Data show that after October 8–10, PM2.5 concentrations rise sharply across all districts, increasing severalfold in areas dominated by private housing. This indicates a substantial contribution from individual household heating systems and solid-fuel combustion, particularly during evening and nighttime hours.

Summer pollution differs in nature from winter smog. During warmer months, the main contributors include dust (including road and construction dust), vehicle emissions, and secondary pollutants formed under hot and sunny conditions. In the absence of rainfall and with weak winds, particles are not removed from the atmosphere and continue to accumulate, even without heating-related emissions.

We examined motor vehicles as a source of air pollution in greater detail in a separate study, available here.

Therefore, summer does not guarantee clean air: during dry and windless weather, pollution levels may remain elevated even in the warmest months.

Transport contributes consistently to background pollution throughout the year, particularly during evening rush hours. However, transport alone cannot explain extreme pollution levels. Its contribution becomes especially critical when atmospheric conditions limit pollutant dispersion.

In the northern and northwestern districts, emissions from major heat generation facilities combine with those from private households. During temperature inversions, this results in persistently high concentrations even at night, when traffic volumes decrease.

Differences between districts are determined not only by emission sources but also by terrain. Nighttime mountain–valley air circulation transports pollutants from the upper and central parts of the city toward lower-lying areas, where they accumulate and combine with local emissions. This makes the northern districts areas of chronic environmental exposure.

Conclusions

Analysis of the 2025 data shows that air quality in Almaty remains persistently poor and poses systemic risks to public health, with pronounced seasonal and geographic disparities. The annual average PM2.5 concentration exceeds the WHO guideline by more than six times, while the number of days with safe air quality continues to decline.

For more than half the year (217 days), Almaty residents were exposed to pollution levels exceeding international air quality guidelines. During winter, episodes of extreme pollution posed a direct threat to the health of the city’s entire population.

A defining feature of 2025 was the substantial variation in pollutant concentrations, ranging from levels close to WHO guidelines to values exceeding Kazakhstan’s maximum permissible concentration by more than four times. This demonstrates the strong dependence of air quality on meteorological conditions, the heating season, and local emission sources.

At the same time, the expansion of the monitoring network during the second half of the year made it possible to capture the true extent of pollution more comprehensively, particularly in districts that had previously been underrepresented in monitoring coverage.

Spatial analysis highlights the systemic nature of the problem: the most unfavorable conditions are consistently observed in the northern part of the city, while foothill districts generally experience relatively better air quality but still fail to meet long-term WHO guidelines.

During winter temperature inversions, pollution spreads across the entire city, reducing geographic differences and increasing the overall risk to public health.

Taken together, the PM2.5 concentration data demonstrate that air pollution in Almaty is a structural rather than episodic problem.

Achieving sustained improvements requires systemic measures, including reducing emissions from heat generation during the heating season, cutting transport-related emissions, prioritizing gasification and modernization of heating infrastructure, and further developing and institutionalizing independent air quality monitoring.

Appendix: Methodology and Notes

This section provides technical details on data collection and explanations of the calculations used in the report.

1. Data Sources and Comparability of Periods

• 2024 vs. 2025 Comparison: To ensure methodological consistency, the comparison with the previous year (in Chapter 1) covers January–September. During this period, a stable network of Clarity sensors was in operation.
• Expansion of Monitoring Coverage: Starting in October 2025, additional data sources (AirGradient, IQAir, OpenAQ, and Airkaz) were integrated into the analysis. This significantly improved data representativeness and reduced the underrepresentation of localized pollution hotspots. However, it also made direct comparisons between the fourth quarter of 2025 and earlier periods less reliable.

2. Defining the Heating Season

For the analysis in Chapter 2, October 10, 2025, was selected as the reference date. This choice was based on two factors:

• Official Start: In 2025, due to an early drop in temperatures, the phased connection of buildings to district heating networks began on October 8–11.
• Response from Private Households: Monitoring data recorded a sharp, widespread increase in PM2.5 concentrations during the second ten-day period of October, confirming the beginning of active solid-fuel combustion in residential areas, independently of centralized heating schedules.

3. Monitoring Parameters

• Geographic Scope: The analysis is limited to the administrative boundaries of Almaty.
• Pollutant: PM2.5 (fine particulate matter with a diameter of ≤2.5 µm).
• Data Aggregation: Data are presented as daily and monthly average concentrations.
• Units of Measurement: All values are expressed in micrograms per cubic meter (µg/m³). This is a physical measure of particulate mass concentration and is not equivalent to the Air Quality Index (AQI) displayed on some air quality monitoring platforms.

4. Standards and Risk Classification

The following reference values were used:

• WHO Guidelines: 15 µg/m³ (daily average) and 5 µg/m³ (annual average).
• Kazakhstan’s Maximum Permissible Concentration (MPC): 35 µg/m³ (daily average).

Air Quality Risk Classification (2025): The report uses an updated classification system that allows for a more detailed assessment of health risks for Almaty residents based on the extent to which pollutant concentrations exceed both national standards and WHO guidelines.

• 🟢 0–15 µg/m³: Air is considered clean and fully complies with current WHO daily guidelines.
• 🟡 15–35 µg/m³: Concentrations exceed WHO guidelines but remain within Kazakhstan’s maximum permissible concentration (MPC).
• 🔴 35–70 µg/m³: Concentrations exceed Kazakhstan’s MPC by up to two times.
• 🟣 70–140 µg/m³: Concentrations exceed Kazakhstan’s MPC by two to four times, posing health risks to the entire population during prolonged outdoor exposure.
• 🟤 Above 140 µg/m³: Extreme pollution levels, exceeding Kazakhstan’s MPC by more than four times.