In Tashkent, air quality temporarily deteriorated sharply. This is expected again tonight
Late Friday evening, a sharp deterioration in air quality was observed in Tashkent. It was caused by dry weather, rising dust, temperature inversion, and weak air circulation. On the night from Saturday to Sunday, air quality may drop again to the "unhealthy for sensitive groups" level.
In Tashkent, air quality sharply deteriorated for a period. A similar occurrence is expected again tonight
In the evening hours of September 18, a short-term sharp increase in the concentration of PM2.5 particles (particles up to 2.5 micrometers in diameter) and especially PM10 (up to 10 micrometers) in the atmospheric air was recorded in Tashkent.
This was reported by the National Committee for Ecology and Climate Change of Uzbekistan, citing information from the Special Commission for Improving the Ecological Situation in the Capital.
According to data from automatic monitoring stations, the concentration of harmful particles began to rise after 18:00, and after 20:00 the growth noticeably intensified. The highest level of pollution was recorded in the interval from 21:00 to 23:00. In particular, at 22:00, the average concentration of PM2.5 across the city was 74.5 µg/m3, and PM10 was 243.6 µg/m3. In some locations, a PM10 concentration of up to 555.3 µg/m3 was recorded.
For reference: the national average daily standard for PM10 is 75 µg/m3 (annual — 500 µg/m3), and for PM2.5 — 60 µg/m3 (annual — 35 µg/m3).
The significantly higher concentration of PM10 compared to PM2.5 indicates an increase in the content of large dust particles in the atmospheric air during this period.
On the night of September 19, specialists from the National Environmental Monitoring Center, together with Uzhydromet specialists, conducted air quality measurements using mobile equipment at three locations in the Mirzo-Ulugbek district. At 2:15, the following indicators were recorded in the Feruza residential area: PM2.5 — 65 µg/m3, PM10 — 77 µg/m3, total dust — 90 µg/m3. At 2:25 on Kasaba Street, the concentration of PM2.5 was 55 µg/m3, PM10 — 63 µg/m3, total dust — 70 µg/m3. At 3:01 on Parkent Street, the indicators were: PM2.5 — 61 µg/m3, PM10 — 65 µg/m3, total dust — 70 µg/m3.
During the measurements, gaseous pollutants such as nitrogen dioxide, carbon monoxide, ammonia, hydrogen fluoride, phenol, and formaldehyde were also monitored. According to the results of the analysis, the maximum one-time concentrations of the measured pollutants did not exceed the standards.
"The analysis shows that several factors simultaneously influenced the occurrence of this situation. Prolonged dry weather created favorable conditions for dust to rise from the soil surface and roads into the atmosphere. Temperature inversion and weak air exchange observed in the evening and night hours contributed to the accumulation of particles in the surface layer of the atmosphere," the report says.
In addition, according to data from the CAMS model (Copernicus Atmosphere Monitoring Service, European computer systems for atmospheric modeling), dust masses with a high concentration of PM10 were observed in the western and northwestern regions of Uzbekistan. Calculations based on the HYSPLIT (Hybrid Single-Particle Lagrangian Integrated Trajectory) model showed that air currents entered Tashkent from the north, northeast, west, and northwest at different altitudes.
After 23:00, the concentration of PM2.5 and PM10 in the atmospheric air began to gradually decrease. By 4:00 on September 19, the average PM2.5 and PM10 indicators across the city had decreased to 22.4 and 61.9 µg/m3, respectively.
"Thus, the situation observed in Tashkent in the evening hours of September 18 and the night of September 19 was in the nature of a short-term dust episode. Dry weather, the rising of local dust, temperature inversion, and weak air exchange created favorable conditions for its formation. The decrease in concentrations at automatic stations after 23:00, as well as the results of on-site measurements conducted between 2:15 and 3:01, indicate a gradual weakening of the dust episode," the committee noted.
According to forecasts, between 21:00 on September 19 and 4:00 on September 20, air quality in Tashkent may temporarily deteriorate, and the Air Quality Index (AQI) may reach the level of 101–150 — "unhealthy for sensitive groups." In the morning hours of Sunday, the polluted air mass is expected to shift in a southwestern direction.
By 8:00–09:00, air quality is expected to return to the "moderate" level.