Variations in aerosol size distributions and deposition fractions in human body based on long-term observations (2007 to 2018)

Fine particles can reach deeply into various tracts in the human body, causing adverse health effects. In addition, particulate matter affects earth energy balance directly, scattering solar radiation, and indirectly, forming clouds and changing cloud properties. In these respects, understanding the variations of aerosol concentrations in each mode of aerosol size distributions and the factors affecting those variations, is important.

In this study, we attempted to separate each mode from the aerosol size distributions obtained from long-term observations with scanning mobility particle sizer (SMPS) (December 2007 to October 2018) in Jeju Island (Gosan, national background concentration network, 33.17˚N, 126.12˚E).

The particle number size distributions (54 channels, from 10.4 nm to 469.8 nm) were separated into three modes using a fitting method based on the multiple lognormal distribution function. We then attempted to examine how these modes of particles have changed in time, and what factors (air trajectories, meteorology, other pollutants, and others) were related to the variations in each mode. We also calculated the deposition fractions of inhaled aerosols in each human respiratory tract from the observed size distributions using the International Commission on Radiological Protection (ICRP) deposition model, and we examined how these deposition fractions vary in different air quality conditions.

More details in the discussion concerning temporal variations in aerosol size distributions, the factors affecting those variations, and variations in deposition fractions in the human body are presented.

Keywords: aerosol, size distribution, deposition fraction, lognormal distribution mode.