Data of IR transmission spectra of aerosol samples and measurements of optical characteristics of surface aerosol at the Zvenigorod Scientific Station are used to study the statistical relationship between the Hänel condensation activity parameter and relative air humidity and the basic chemical components of aerosol, namely, sulfate, nitrate, and mineral components, contained in particles with diameters of 1–2 μm. It is found that the Hänel parameter of nitrate-containing surface aerosol decreases with an increase in relative air humidity. An increase in the fraction of nitrates in micron particles is likely to lead to a minor increase in the Hänel parameter. Poorly soluble mineral particles present in the 2-micron fraction of aerosol lead to a decrease in the Hänel parameter. Values of the Hänel parameter, characteristic for sulfate aerosol, are likely to be in the range of 0.4–0.6. Seasonal variations in the Hänel parameter are caused by changes in the aerosol chemical composition, to some degree.