National Committee on Ecology and Climate Change of the Republic of Uzbekistan

Based on available monitoring data, from 5:00 p.m. on 6 October to 10:00 a.m. on 7 October, the citywide average concentration of fine particulate matter (PM2.5) was 43.5 µg/m³, while the average PM10 concentration was 97.2 µg/m³. The average AQI for this period was 117, corresponding to the “Unhealthy for Sensitive Groups” category. Under the national air quality index, the average PM2.5 concentration remained within the “Green” category, while PM10 was at the “Yellow” level. At 10:00 a.m. on 7 October, the citywide average PM10 concentration reached the “Orange” level.

The deterioration in air quality was influenced by unfavourable meteorological conditions that limited the dispersion of pollutants. Wind speeds of around 1 m/s, combined with a strong nighttime temperature inversion, reduced air circulation and vertical mixing.

According to vertical monitoring data, a temperature inversion was observed from 11:00 p.m. on 6 October until 8:00 a.m. on 7 October. The temperature difference within the inversion layer ranged from 1.8°C to 6.7°C, indicating a strong inversion. Under these conditions, a layer of relatively warm air forms above colder air near the ground, preventing pollutants from dispersing vertically.

Similar conditions may occur temporarily during nighttime and early morning hours through the end of the week.

For reference: Pursuant to a joint decision of the Ministry of Health of the Republic of Uzbekistan and the National Committee on Ecology and Climate Change, titled “On the Approval of the Procedure for Introducing a National Air Quality Indexing System and Preventive Measures to Reduce the Impact of Air Pollution on Public Health”, Uzbekistan has established a national air quality indexing system based on PM2.5 and PM10 concentrations.

Ambient air quality is currently under continuous monitoring by the Special Commission.