ISRP 2002 abstract
| Presenter/author | Title | Abstract |
|
Enjoji,
Takaharu Research Dept., Shigematsu Works Co., Saitama, Japan
|
An Evaluation of Filtering
Efficiency for Reusable-Particulate Respirators Simulating Actual
Conditions
|
The Ministry of Health, Labor and Welfare
published the new regulation for particulate respirators in Sept. 2000.
This regulation adopts a continuous measurement method (loading) for the
filtering efficiency that NIOSH adopted in 1995. Unlike the measurement
of initial filtering efficiency adopted in the previous regulation, this
method can evaluate a declining filtering efficiency caused by filter
degradation. However, this regulation may not always meet the actual
working conditions, because users of reusable-particulate respirators
tend to use one filter repeatedly. Therefore we evaluated the
performance of RL2-series (filtering efficiency : more than 95% against
DOP) electrostatic and mechanical filters, and RS2-series (filtering
efficiency : more than 95% against NaCl) electrostatic filters when
loaded intermittently with a challenge aerosol of approximately 50mg/day
for 5 days, simulating actual conditions. As a result, the filtering
efficiency for electrostatic filters declined as the loaded volume
increased, while mechanical filters maintained a high filtering
efficiency against any challenge aerosols.
NIOSH suggested service-time limits for N and R-series filters to take into consideration the filter degradation. Regarding use limitation, we recommend some actions like NIOSH should be taken in the Japanese regulation for reusable-particulate respirators in the future. |