Effect of respiratory protective equipment (RPE) fit testing to decrease an acute decline in FEV1 induced by chromium in stainless steel welder

Introduction
Respirator fit-testing is one of the procedures which should be performed as an integrated part of hazard prevention effort by respirator protection device usage. The purpose of this research was to evaluate effect of RPE fit testing aimed at preventing an acute decline in FEV1 induced by chromium in stainless steel welder and to assess the convenience of RPE usage. 

Methods
This research was conducted on clinical trial (cross over) design between workers who wore tight fitting RPE and workers who wore regular RPE with single blind at FEV1 evaluator. Declining of FEV1 was measured on 24 respondents by comparing prior working FEV1 value and end working FEV1 value in a work shift. The convenience of RPE usage was assessed by questionnaire. Respirator fit-testing was conducted by qualitative method with FT-30 bitter instrument from 3M. Chromium level at working environment was measured by NIOSH 7072-1994 method. 

Results
Chromium environment level was 3.45 ug/m³. Should respondents worn regular RPE, the mean of FEV1 prior working was 3403,8 ml and end working was 3247,5 ml. Having worn tight fitting RPE, the mean of FEV1 of respondents prior working was 3359,0 ml and end working was 3339,6 ml. There was a significant differences that FEV1 declining when respondents wore regular RPE was higher than that on wearing tight fitting RPE (dependent t test p=0.011). Tight fitting RPE was also more convenient to wear compare to regular RPE (Mc Nemar test p= 0.022). 

Discussion
Tight fitting RPE proved to be effective in preventing an acute decline in FEV1 which were visible from (1) There was significant acute decline in FEV1 when respondents wore regular RPE but not when wearing fit RPE, (2) The differences of FEV1 declining on both treatments was statistically significant. Tight fitting RPE had better convenience level compare to non fitting RPE.