Filtration efficiency of the ramathibodi nasal filter evaluated by rhinomanometry in high concentration level of laser smoke particle.

Under conditions with a high concentration level of laser smoke particles, the filtration efficiency of the Ramathibodi nasal filter was studied. Different kinds of filter material in the Ramathibodi nasal filter were evaluated in human adults with an anterior standard rhinomanometric method. The Ramathibodi nasal filter with three-layers of a half-face mask filter and a 4 mm thickness polyurethane foam put inside was applied in a simulated human airway. The experiment was conducted in the Otolaryngology Department, Ramathibodi Hospital from October to December 2001. The amount and size of laser smoke particles were measured by a laser diode portable dust monitor. The amount of residual laser smoke particles in the simulated human airway without the Ramathibodi nasal filter of PM2.5, PM10 and PM15 were 100.91 +/- 7.65, 109.10 +/- 7.87 and 120.18 +/- 14.28 mcg/m3 respectively. The amount of residual laser smoke particles in the simulated human airway with the Ramathibodi nasal filter of PM2.5, PM10 and PM15 were 85.55 +/- 3.42, 92.18 +/- 4.40 and 99.72 +/- 5.02 mcg/m3 respectively. The filtration efficacy of the Ramathibodi nasal filter showed a high statistically significant difference with a p-value of <0.001 for three particle sizes. High concentration of laser smoke particles in an operative room represented suspended particulate matters which are very dangerous for human healths. The Ramathibodi nasal filter as a personal respiratory protective device applied in human nasal vestibules could protect the human airway from atmospheric suspended particulate matter.

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.

The 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, PM10 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 of PM15, PM10 and PM2.5 were 48.1 +/- 9.9, 39.1 +/- 9.1 and 33.2 +/- 7.2 mcg/m3 respectively. Ramathibodi 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.