The basic sources of air pollution over the Baikal’s area are towns and villages located around the lake, especially along its south shore. All the emissions from Baikalsk-town (including BPPM) and Slyudyanka get into the lake. The surrounding mountains protect the Baikal from remote polluting sources but prevent any dispersion of the local emissions. The valley of the river Angara is a passageway to the lake for prevailing northwest winds, which bear air emissions of Irkutsk-Cheremkhovsk industrial center along the valley to Lake Baikal. The impact of air emissions depends on the season. In December winds are light and the emissions rarely reach the lake. In April-May winds are much stronger. Sometimes air emissions can get into the lake from the valley of the Selenga, including Ulan-Ude, Selenginsk and Gusinoozersk. The highest pollution level was detected in the southern part of the Baikal. The most frequent polluting agents are: solid particles, sulfur dioxide, carbon oxide, nitrogen dioxide, and hydrocarbons. During rain periods the polluting agents get into the lake and its drainage basin.
Among 45 Russian cities with highest level of air pollution 7 cities are located in Irkutsk Region (data of IUGMS, 1995). These are Angarsk, Bratsk, Zima, Irkutsk, Usolie-Sibirskoe, Cheremkhovo, and Shelekhov. Regarding the air pollution aspect, east-Siberian economic region is one of the worst areas in Russia to live in.
Five cities are located within 200-km area of the Baikal air basin – Irkutsk, Shelekhov, Angarsk, Usolie-Sibirskoe and Cheremkhovo (Irkutsk-Cheremkhovsky industrial center). Such a significant air pollution of the cities is caused by emissions of industrial factories and facilities: heat-and-power stations, coal, mining, aluminum, chemical, machine-building, metalworking, light and food industries. The total emission of stationary and mobile sources in Irkutsk Region in 2000 made 633,3 thousand tons. The total air emission reaching the Baikal area made up to several thousand tons. The air emission of Irkutsk-Cheremkhovsky industrial center spreads over an area of 30 thousand sq. km from the town of Tulun to Lake Baikal.
Towns of Buryatia located near the lake’s shore (for example, Severobaikalsk, Kamensk, and Selenginsk) add to the total air pollution.