Error Analysis for Determination of Total Dust Concentration in Air of Workplace

Objective To measure total dust concentration in the air of workplace and analyze the sources of errors in determination.

Methods Through eliminating static electricity of filter, changing temperature and humidity in balance room, and simulated sampling in clean room, we analyzed the potential error sources in determination of total dust concentration in workplace air, including membrane preparation, sampling, and weighing processes.

Results Following the requirement for minimum total dust increment on filter of 0.1 mg, the error caused by static electricity of filter was -50%-450%(n=8); that caused by position change on tray and having filter without static electricity eliminated and folded two times after sampling was 110%-880%(n=10); that caused by filter weight loss due to sampling flow(20 L/min) was -20%-0%(n=8); that caused by temperature(21.9-31.2℃) and relative humidity(50.8%-66.1%) change in balance room was -30%-40%(n=8). However, no obvious change was observed in weighing results of filter with static electricity eliminated and position change on tray.

Conclusion Static electricity of filter is a main factor that affects the accuracy of weighing of total dust concentration in workplace air. Through quality control measures such as eliminating static electricity of filter and keeping temperature and humidity in balance room consistent before and after sampling, more accurate dust concentration in polypropylene workplace air could be achieved.