New method to measure particle surface area deposition in the human respiratory tract

Particle deposition efficiency in the different regions of human respiratory tract as a function of particle size, Lepistö et. al 2020.

In our new study, we developed a measurement method to analyze particle surface area deposition in the human respiratory tract.

Fine particles are known to have negative effects on human health. One way to estimate the harmfulness of particles is to measure the particle surface area concentration, which correlates strongly with the negative health effects. One reason for this correlation, is the production of reactive and toxic oxygen species on the particle surface.

Lung-deposited surface area (LDSA) is a metric developed to measure particle surface area deposition in the human respiratory tract. LDSA is most often used to measure the surface area deposition of particles in the alveolar region of human lungs. This region is considered the most relevant region for the negative health effects, as the interaction with lungs and pulmonary circulation takes place there.

There are multiple sensors that measure LDSA with a relatively simple method by measuring the electric current of particles after a diffusion charger. However, this method has its inaccuracies especially with particles larger than 300 nanometers and it may underestimate the real LDSA concentration significantly, as particles up to over 10 microns can deposit in the alveolar region of lungs. Our new method, presented in Lepistö et al. 2020, can be used to measure LDSA concentration and size distribution reliably in the size range from 6 nm to 10 µm, which covers almost the whole alveolar deposition region. Furthermore, this method enables measurement of the surface area deposition in the other regions of the human respiratory tract as well.

Measuring the size distribution can give important information about the role of different particle types in the respiratory deposition, and thus give information on the health effects of different particle types.

Teemu Lepistö, Heino Kuuluvainen, Paxton Juuti, Anssi Järvinen, Anssi Arffman & Topi Rönkkö (2020) Measurement of the human respiratory tract deposited surface area of particles with an electrical low pressure impactor, Aerosol Science and Technology, https://doi.org/10.1080/02786826.2020.1745141