The article presents the results of experimental toxicological and olfacto-odometric studies on maximal (onetime) allowable concentrations of α- and β-pinene in ambient air of urban and rural settlements.

Introduction. Expansion of approaches to assessing the odour of substances polluting the atmospheric air, with the introduction of odorimetry (measuring the strength, intensity of odour) into practice indicates that the existing classification of the olfactory hazard of odorous components according to the “undefined” odour needs to be updated. Materials and methods. Experimental studies with the definition of a quantitative expression of the dependence of the likelihood of odour detection of different strengths on the concentration were carried out using the example of 13 mixtures of volatile organic substances on a dynamic olfactometer. The volume of olfacto-odorimetric studies was over 4600 measurements. Statistical data analysis was performed using the Probit Analysis computer program (v.4.0). Results. Based on the studies carried out, it was found that the lower the ratio of the concentration causing a 5% probability of detection of odour with a strength of 3 points (threshold of “offensiveness”, Limoff.) to the concentration causing a 50% probability of “undefined” odour (detection threshold or the threshold for an “indeterminate” odour, Limindef.), the more dangerous the substance is in relation to the development of an “offensive” odour. A new classification of the hazard of substances is proposed, taking into account the “offensiveness” of their odour: extremely offensive (Limoff./Limindef. ≤1.5), offensive (Limoff./Limindef. ≤3), moderately offensive (Limoff./Limindef. ≤6), slightly offensive (Limoff./Limindef. > 6). Limitations. This study is not without certain limitations, among which the main ones are the use of a relatively new method that requires additional testing; a relatively small number of study participants; methods for presenting odor stimuli and registering them. Conclusion. The ability of odorous substances to cause a feeling of “offensiveness” (“annoyance potential”), and, accordingly, their hazard class depends on the characteristics of the spectra of graph dependences of the probability of different strengths odour on the concentration on the probabilistic grid and the ratio of the parameters of the resulting dependencies.

Results of experimental studies are reported on the substantiation of the maximum single permissible concentration (MAC maximum single) of volatile organic compounds, formed during a high temperature processing of wood in chipboard production (based on tererpene hydrocarbons), in the atmospheric air of residential areas at the level of 0.05 mg/m3. The magnitude was established on the basis of olfacto-odorimetry taking into account new approaches to the determination of «obsessive» odor thresholds as a limiting criterion for the MAC maximum single justification in accordance with the international practice of setting odor limits and our home experience gained in the standardization of odorous substances in the ambient air. The selection of priority substances for the control of the designed value (α-pinene, β-pinene, 3-carene, limonene, camphene) was based on the analysis results of the composition of releases from a high temperature processing of wood and atmospheric air in the enterprise location area.

The article provides an overview of the foreign literature data on the justification of permissible content of odourous substances in the ambient air. The process of harmonization of Russian legislation with international norms and rules, including the field of regulating atmospheric air pollution with specific odours, is shown to necessitate significantly expanding approaches to the issues of standardization and assessing environmental pollution by emissions from enterprises - odour sources. Analysis of foreign experience in odour management in the environment shows the main criteria for assessing air quality to include the absence of “annoyance” of the population by odours, maximum permissible concentrations for individual substances, maximum permissible concentrations for ambient odours, permissible odour frequency, minimum distances from the source, odour intensity, the maximum permissible amount of emissions, compliance with technological standards. Accordingly, in different countries recommended or mandatory limiting values were established on the base on which criterion for assessing odour exposure is decisive in this case. Typically, different jurisdictions use more than one approach to odour assessment, as do various regulatory indicators depending on the situation with the type of enterprise, the characteristics of residential sites and other receptor points. According to many authors, the application of various air quality standards for odour and a carefully thought-out approach to odour management can successfully or completely resolve most conflicts when working with the local population. The search for sources devoted to the issues of standardization of odourous substances was carried out in the text databases as PubMed, Scopus, Science Direct, Web of Science, Research Gate, Springer Link and the scientific electronic library eLibrary.ru. The article analyzes the articles of journals indexed in the RSCI, Scopus, for 2001-2021.