Air Pollution in Georgia

The maps in Figure 4 show the dispersion of NO₂ over Georgia from May 2018 to December 2022. The distribution of the pollutant varies in the exact locations over the five years, mainly in the axial valley between the northern and southern mountain ranges. Over five years of measurements, pollutant levels remained highest in Tbilisi, Kvemo Kartli, and Shida Kartli, where dense population and heavy traffic contribute to air pollution. A noticeable rise in values in 2019 may be linked to missing early 2018 data when domestic heating increased NO₂ levels.

Figure 5 shows a comparison of the average NO₂ values in the regions of Georgia between 2018 and 2022, while Figure 6 shows a comparison of the average values of 20 municipalities and self-governing cities for the selected period. As for the regions, a significant maximum of average NO₂ concentrations is found in the Tbilisi region. Slightly higher values occur in the neighbouring regions of Kvemo Kartli and Shida Kartli, with higher urbanisation levels and more industrial towns. As for the municipality, Rustavi had the highest NO₂ levels, due to its steel and cement industries, along with heavy traffic from commuters traveling to Tbilisi.

NO₂ pollution in Georgia follows seasonal patterns (Figure 7), peaking in winter due to increased heating and generally increased energy production. The distribution of pollution remains consistent during the seasons; the highest values occur in the south-east of the country (around Tbilisi and Rustavi). Higher values are also found in the Colchis Lowland, bordered by mountains that hinder the diffusion of air. Unfavourable weather conditions and wind direction can contribute to worsening the situation.

In general, it can be assumed that larger cities show higher NO₂ concentrations (Figure 10). However, in several cities such as Kaspi (Figure 8), Marneuli and Gardabani, with average populations, concentrations of NO₂ that were multiple times higher were detected. This is often due to local industries and traffic emissions. At the same time, the region around Tbilisi has poor air circulation due to elevated terrain. The pollution continues from Tbilisi towards the south-east, where are cities of Gardabani and Rustavi. There were also detected elevated NO₂ levels. Batumi and Kutaisi, which lack heavy industry and have better air circulation, show lower NO₂ levels despite their population sizes.

The Rustavi-Gardabani-Marneuli region, which plays a vital role in Georgia’s economy, has significantly higher NO₂ concentrations, mainly due to large-scale industrial activities, cement factories, and heavy traffic. Rustavi is home to one of Georgia’s largest steel plants (Figure 9), a major cement factory, and Rustavi Azot—one of the leading fertiliser and industrial chemical producers in the Caucasus region—along with other industrial facilities that significantly contribute to air pollution. Foreign-owned companies in these areas have failed to implement effective environmental responsibility measures. Gardabani faces high levels of air pollution from various sources, including cement factories and transport emissions. The town is located on a major transportation route between Georgia and Azerbaijan, which means that a large number of heavy trucks and other vehicles pass through the town every day. Due to Marneuli’s proximity to Rustavi and Gardabani, high NO₂ concentrations can also be observed there, despite the absence of polluting industries in the town.

Elevated NO₂ concentrations were also observed in Kaspi, where one of the largest cement plants and the large Ksani Glass Factory are located. The area’s terrain also forms a pocket-like shape that hinders air circulation and traps pollution.

Because of human activities, most pollution is found in the densely inhabited cities (Figure 11). Higher population density is connected to more vehicles and greater economic activity. In the less populated mountainous areas, the concentrations do not reach such values.

The relationship between road density and NO₂ concentrations can be observed in Figure 12. NO₂ pollution is strongly linked to transportation.

The high number of old, poorly maintained vehicles, along with traffic congestion, further worsens air quality in cities.

Between 2018 and 2022, CO levels remained relatively stable, with the highest concentrations recorded in 2021 (Figure 14). The increase in 2021 may be linked to regional drought conditions, which limited the presence of moist air and hydroxyl radicals (OH) that typically help break down CO. Airflow patterns could have also transported CO from neighboring regions, such as Turkey and Central Asia, where severe droughts occurred that year.

The average CO concentrations within each region can be seen in Figure 15. The highest concentrations were detected in the regions of Tbilisi, Guria, and Imereti. No significant anthropogenic pollution sources were detected.

In Figure 16, the highest concentrations in 20 municipalities and self-governing cities of Georgia can be observed, with the values being rather balanced. All the municipalities that are displayed tend to be located in lowland terrain or at the edge of the mountains.

Seasonal patterns show that CO levels rise in winter and early spring, peaking in April, before sharply declining (Figure 17). This increase is likely due to heating emissions and cloud cover preventing CO dispersion. A secondary peak in August may be linked to high temperatures and more frequent wildfires.

Despite investigating potential anthropogenic CO sources, such as Rustavi’s industrial plants, no significant human-caused CO hotspots were detected. This confirms that natural factors play a dominant role in CO levels in Georgia, rather than industrial or transportation-related emissions.

The distribution of PM₁₀ in the Georgian regions (Figure 20) shows that the concentrations in the Tbilisi and Kakheti regions only slightly exceed the WHO’s recommended limit and the rest of the regions remain well below the limit.

The highest average PM₁₀ levels are found in Rustavi and Tbilisi (Figure 21). According to the global model (Figure 22), Dedoplis Tskaro town (located in the Kakheti region, missing in the European model) has the highest PM₁₀ concentrations among municipalities, followed by Singhnaghi, Lagodekhi, and Qvareli (Kakheti region). This is caused by the enhanced diffusion of particles, which stems from the arid climate and sparsely vegetated land cover.

PM₁₀ concentrations were higher before the COVID-19 pandemic, peaking in 2019, with a gradual decline from 2020 to 2022. Lockdowns had little impact on pollution levels, suggesting natural factors play a larger role.

Seasonal trends indicate higher PM₁₀ levels in summer and spring, as winds transport dust westward, affecting Tbilisi and Rustavi. Winter and autumn peaks are probably linked to household heating using coal and wood. Industrial cities like Rustavi and Gardabani consistently show high PM₁₀ levels, independent of population size (Figure 23).

The global model (Figure 24) fails to observe more subtle changes and the temporal trend seems to adhere predominantly to the natural processes of dust and aerosol distribution throughout the year. Concentrations are thus elevated in spring and summer, when drier and windier periods cause resuspension of the particles, primarily in the east of the country and on the west coast.

Figure 25 and Figure 26 present monthly average PM₁₀ concentrations from 2018 to 2022, showing higher levels in summer across both models. The European model excludes Kakheti, which has the highest concentrations in the global model, while Tbilisi records the highest values in the European model and ranks second in the global model. Seasonal variations are influenced by natural factors, with particle re-suspension in the east and west contributing to elevated concentrations. 

Air pollution levels in cities with over 10,000 inhabitants do not directly correlate with population size. Global model values tend to be higher and more generalized, while the European model shows similar high concentrations in industrial cities like Gardabani and Rustavi (Figure 27).