Distribution of micro-sized range solid particles in the human airways: field experiment

Introduction. Ambient air pollution is a widespread and pressing issue. This necessitates the development of methods for estimating and predicting progression of pathologies on the base of evolutionary mathematical models. Adaptation of the theoretical model to practice requires identification and verification procedures in real conditions of contamination of inhaled air with dust particles of various compositions.

The purpose of the work was to investigate regularities of distribution of dust particles with a different disperse, component and morphological structure in the human airways after inhalation from ambient air. The study involved performing a field experiment.

Materials and methods. We accomplished several investigations in 3 zones with different levels and structures of ambient air pollution. Disperse, component, and morphological structures of particles occurring in ambient (inhaled), deposited in various sections of the human airways, in exhaled air and blood were examined by electronic microscopy.

Results. Air quality in zones 1 and 2 did not comply with hygienic standards for suspended particles, PM₁₀, PM_2.5, metal compounds, etc. (up to 3.29 MPCm.s., 3.2 MPCav.s., 2.91 MPCav.y.) and formed increased hazard quotient for manganese, copper, nickel and their compounds, inorganic fluorides, suspended particles (up to 5.48 HQac, 3.42 HQch), respiratory and other hazard indices (up to 5.48 HIac, 8.59 HIch). The degree of sedimentation of small particles (PM_2.5 or less) in different parts of the respiratory tract is uneven, they are able to penetrate into the lower airways and lungs of humans. More than 65% of all the particles deposited in the upper airways had a diameter bigger than 10 µm. PM_2.5 accounted for more than 60 % in sputum in the lower airways and the share of PM_1.5 reached 46.7 %. Particles smaller than 1.5 μm (90.5%) were predominantly recorded in blood biosubstrates, of which up to 88.1% of the particles had a sphericity of 0.9–1.0.

Limitations. Limited degree of precision of location of the examined sections in the respiratory system.

Conclusion. Common deposition regularities are mostly determined by sizes and morphology of dust particles. The component structure of inhaled air has practically no effects on regularities of particle deposition in various sections of the respiratory system; however, it can have substantial influence on types of pathologies progressing in the body. High shares of PM_1.5 identified in inhaled air, the lower airways and blood require considering levels of PM_1.5 and smaller particles in ambient air in settlements to be covered by hygienic standards. In future, the study results will be used in numeric modelling of accumulation of functional respiratory disorders and associated pathologies of other organs and systems and in predicting development of pathologies based on evolution mathematical models.

Compliance with ethical standards. The study was approved by the local ethical committee of the Federal Scientific Center for Medical and Preventive Health Risk Management Technologies (meeting protocol No. 2 dated 11.02.2021), and the Helsinki Declaration of the World Medical Association (as amended 2013) was carried out.

Contribution:
Zaitseva N.V. — the study concept, organizing and accomplishing a field experiment, text editing, approval of the final version of the article;
Kiryanov D.А. — the study concept and design, writing;
Kleyn S.V. — hygienic assessment, selecting points for accomplishing a field experiment, writing;
Tsinker М.Yu. — the study concept and design, experiment data analysis, description of the results, writing;
Andrishunas А.М. — hygienic assessment, description of the results, writing.
All authors are responsible for the integrity of all parts of the article.

Conflict of interest. The authors declare no conflict of interest.

Acknowledgement. The processing of the results of the experiment was carried out with the support of the state assignment of the Ministry of Science and Higher Education of the Russian Federation for the implementation of basic scientific research (project FSNM-2023-0003).

Received: March 9, 2023 / Accepted: May 31, 2023 / Published: June 20, 2023