Efficacy of the Ramathibodi Nasal Filter in a Simulated
Human Airway Evaluated by a Laser Diode Portable Dust
Monitor Under Low Laser Smoke Particle Concentration
KUNCHITTHAPE TANPOWPONG, M.D.*,
CHUMROON CHIRATTHITI, M.S. (Environmental Science)**
Affiliation : * Department of Otolaryngology, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok 10400,
** Environmental Health Center Region One, Department of Health, Ministry of Public Health, Nonthaburi 11000,
Thailand.
AbstractThe Ramathibodi nasal filter attached to a simulated human airway was proposed to filter
laser smoke particles. The simulated human airway composed of nasal and pharyngeal model, airway
passage and lung model machine which mimicked the human respiratory system. The laser smoke
particles represented a suspended particulate matter in a highly air-pollutted area such as at a main
roadside in Bangkok. The experiment was done in the Department of Otolaryngology, Ramathibodi
Hospital, from January to March 2000. The simulated human airway got an equal amount of laser
smoke particles in a sealed plastic box for 1 min. The residual amount of laser smoke particles in a
closed system of the simulated human airway was measured by a laser diode portable dust monitor
for 1 min: in each cycle and calculated as a mean and standard deviation. Without the Ramathibodi
nasal filter of 39 sample pairs, the amounts of PM15, PMlO and PM2.5 were 52.3 ± 6.8, 43.0 ± 4.9
and 37.0 ± 3.5 mcg/m3 respectively. With the Ramathibodi nasal filter of 39 pairs sample, the amounts
ofPM15, PMlO and PM2.5 were 48.1 ± 9.9, 39.1 ± 9.1 and 33.2 ± 7.2 mcg/m3 respectively. Ramathi
bodi nasal filter efficacy for all laser smoke particle sizes evaluated statistically using t-test showed
significant differences from those without the filter. Filtration efficacy should be tested further in
higher concentrations of laser smoke particles and applied in human nasal vestibules under a critical
air-polluted condition.
Keywords : Simulated Human Airway, Laser Smoke Particles, Ramathibodi Nasal Filter, Laser
Diode Portable Dust Monitor
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