According to modern estimates, the largest contribution to global warming is made by carbon dioxide, while its share is 60-70%. However, studies of the last decade also indicate a large impact on the planet’s climate of “short-lived climate pollutants”, which mean forcing substances with “lifetimes” in the atmosphere from several days to several years. These pollutants include black carbon. In the Russian Federation, black carbon refers to the substance “carbon (soot)”, which is a dispersed carbon product of incomplete combustion or thermal decomposition of hydrocarbons, consisting of particles of various shapes and having a black color. Soot is a strong carcinogen. It is the 2nd class harmful substance and carried by winds for thousands of kilometres. It has been found that black carbon retains several hundred times more heat than carbon dioxide does. Therefore, reducing black carbon emissions is one of the most important challenges in the fight against climate change. Therefore, the task arises of a comprehensive study of all aspects related to black carbon emissions. Based on this, experimental studies of the emissions of soot particles formed in the combustion chambers of boilers of various capacities and designs were carried out during the combustion of various solid, liquid and gaseous fuels. The structure, size and quantitative composition of soot particles, as well as their constituent elements, were studied using scanning electron microscopy. The research results made it possible to propose a more extended approach for choosing the values of specific soot emissions from the combustion of various fuels in heat generators, which should be used in the inventory of emissions of this pollutant.