## 2 Materials and Methods  
### Description of Sampling Sites  
Air sampling of VOCs was conducted at six sites S1-S6 (Table 1). Each sampling site was more than 15 m away from the road. VOCs sampling locations were selected to represent five districts (Almaly, Auezov, Bostandyk, Medeu, and Turksib) of Almaty (Figure 1).  
Average temperatures in sampling periods in winter, spring, summer, and autumn in Almaty in 2020 were \(-\)5.7, 15.8, 24.3, and 9.3 \({}^{\circ}\)C, respectively. The heating season in Almaty lasted from 15 October 2019 to 21 April 2020 and resumed on 28 September 2020.  
Concentrations of NO\({}_{2}\), SO\({}_{2}\), and CO were obtained from The National Air Quality Monitoring Network (NAQMN) operated by the National Hydrometeorological Service of  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Code** & **Crossroad** & **Coordinates** & **Elevation** & **Distance** & **Distance** & **Objects Close to Sampling Sites** \\ \hline S1 & Radostovets str.- & 43\({}^{\circ}\)12.007\({}^{\prime}\) N & 978 & 13 & 26 & Residential area with high buildings, Mega Center Alma-Ata mall, Kazakhstan-Russian Gymnasium No 38, Almaty Management University \\ S2 & Mendikulov str.- & 43\({}^{\circ}\)13.654\({}^{\prime}\) N & 944 & 15 & 22 & Instidential and office areas with high buildings, Al-Farabi highway \\  & al-Farabi ave. & 76\({}^{\circ}\)57.252\({}^{\prime}\) E & 944 & 15 & 22 & Instidential and office areas with low buildings, Atrium mall, parking, Kazakhstan Academy of Labor and Social Relations, Kazakhstan-Russian Medical University, crossroad with high traffic load \\ S3 & Nauryzbay Batyr str.- & 43\({}^{\circ}\)16.099\({}^{\prime}\) N & 764 & 11 & 18 \\ str.- & Raiymbek ave. & 76\({}^{\circ}\)56.062\({}^{\prime}\) E & & & & \\ S4 & Papanin str.- & 43\({}^{\circ}\)19.095\({}^{\prime}\) N & 700 & 14 & 12 & Instidential and office areas with high traffic load, avenue \\ S5 & Suyunbay ave. & 76\({}^{\circ}\)57.781\({}^{\prime}\) E & 700 & 14 & 12 & Instidential and office areas with high traffic load, avenue \\ S5 & Raiymbek ave.–Akhrimenko str. & 43\({}^{\circ}\)14.950\({}^{\prime}\) N & 43\({}^{\circ}\)14.950\({}^{\prime}\) N & 770 & 6 & 23 & Private low buildings, crossroad with high traffic load, bakery plant \\ S6 & Shevchenko str.- & 43\({}^{\circ}\)14.612\({}^{\prime}\) N & 803 & 9 & 22 & Instidential areas with middle-rise buildings \\  & Gagarin ave. & 76\({}^{\circ}\)53.586\({}^{\prime}\) E & 76\({}^{\circ}\)507\({}^{\circ}\) E & 77\({}^{\circ}\)07\({}^{\circ}\) E & 77\({}^{\circ}\)507\({}^{\circ}\) E & \\ \hline \hline \end{tabular}
\end{table}
Table 1: VOCs sampling sites.  
Figure 1: Map showing the location of the sampling sites in Almaty, Kazakhstan.  
Kazakhstan \"Kazhydromet\" and were used for correlation analysis. Air is analyzed using OP-824 TTs and OP-280 aspirators, K-100 gas analyzer, and AFA-VP-20-1 filters (JSC OPTEK, Saint Petersburg, Russia). Data are published each month and year by \"Kazhydromet\" in the information bulletins [27].  
The data of PM\({}_{2.5}\) were obtained from the public network \"Airkaz\" [28], which uses PM\({}_{2.5}\) sensors (The Plantower Pms5003, Beijing, China) for air quality monitoring based on PM\({}_{2.5}\) concentrations. Four stations (Figure 1, Table S1 in Supplementary Materials) of the network, close to VOCs sampling sites, were selected for this study. Due to technical problems of sensors, 23.3% of the data on PM\({}_{2.5}\) concentrations were omitted.  
Spatial distribution of total VOCs (TVOCs) across Almaty in different sampling periods in 2020 were obtained using Geographic Information System software--ArcGIS (ArcMap 10.8.1) and cokriging Geostatistical Analyst tool. A simple cokriging method with normal score transformation and exponential model of semivariogram was used to build the map for the primary dataset. As a secondary dataset, the digital elevation model (DEM) of Almaty was used. The DEM was obtained from United States Geological Survey and Shuttle Radar Topography Mission data.