Experimentally determined human respiratory tract deposition of airborne particles at a busy street.
Traffic is one of the major sources of harmful airborne particles worldwide. To relate exposure to adverse health effects it is important to determine the deposition probability of the inhaled particles in the human respiratory tract. The size-dependent deposition of 12-580 nm particles was measured with a novel setup in 9 healthy subjects breathing by mouth on the windward side of a busy street in Copenhagen, Denmark. The aerosol was characterized both at the curbside and, to obtain the background concentration, at rooftop level. Particle hygroscopicity, a key parameter affecting respiratory tract deposition, was also measured at the same time of exposure. The total deposition fraction of the curbside particles in the range 12-580 nm was 0.60 by number, 0.29 by surface area, and 0.23 by mass. The deposition fractions of the "traffic exhaust" contribution, calculated as the hydrophobic fraction of the curbside particles, was 0.68, 0.35, and 0.28 by number, surface area, and mass, respectively. The deposited amount of traffic exhaust particles was 16 times higher by number and 3 times higher by surface area compared to the deposition of residential biofuel combustion particles investigated previously (equal inhaled mass concentrations). This was because the traffic exhaust particles had both a higher deposition probability and a higher number and surface area concentration per unit mass. To validate the results, the respiratory tract deposition was estimated by using the well-established ICRP model. Predictions were in agreement with experimental results when the effects of particle hygroscopicity were considered in the model.
Löndahl
Jakob
J
Division of Nuclear Physics, Department of Physics, Lund University, PO Box 118, SE-221 00 Lund, Sweden. jakob.londahl@nuclear.lu.se
Massling
Andreas
A
Swietlicki
Erik
E
Bräuner
Elvira Vaclavik
EV
Ketzel
Matthias
M
Pagels
Joakim
J
Loft
Steffen
S
D000328:Adult; D000336:Aerosols; D000368:Aged; D000393:Air Pollutants / Q000032:analysis*; D000397:Air Pollution; D001674:Bioelectric Energy Sources; D002947:Cities; D003718:Denmark; D004784:Environmental Monitoring / Q000379:methods*; D004867:Equipment Design; D005260:Female; D006801:Humans; D019570:Inhalation Exposure; D008297:Male; D008875:Middle Aged; D012137:Respiratory System / Q000187:drug effects*; D001335:Vehicle Emissions
D000336:Aerosols; D000393:Air Pollutants; D001335:Vehicle Emissions