Exposure to PM1 in a machine shop

Sub-micron particle exposure, workers’ time-activity patterns, particle dose, and risk scenarios were investigated in a university machine shop. Sub-micron number (PN 1) and mass (PM1) concentrations, PM10 concentrations, and micro-environmental conditions were recorded simultaneously over two spatial zones. Average measured number concentration of PN1 was 13,100 ± 1,940 #·cm—3. Average PM1 and PM10 concentrations were 0.03 ± 0.03 mg·m—3 and 0.16 ± 0.12 mg·m —3, respectively. Turning lathes, boring machines, welding, and the presence of workers were all emission sources. Additionally, short-term exposures to high number concentrations were observed. As no thresholds for PM1 exist, current PM2.5 and PM10 limit values were used to estimate risk quotients. Risk quotients of near-field exposure for PM1 and PM10 mass concentrations ranged from 0.6 to 3.2. Daily particle dose ranged from 7.2 to 22·10 8 #·(kg—1 body-weight·8 h —1-shift), while total uptake of the measured particle mass concentrations led to average doses of 3.6 μg·kg— 1 bw·8 h—1 -shift for PM1 and 21 μg·kg—1 bw·8 h—1-shift for PM10, respectively