Table 3. Number, duration of exposure and time to progression of chest radiographic change in two or more steps subcategories

From

Radiographic Progression among Sandstone Workers:A Preliminary Result

Jedsada Panthong, Naesinee Chaiear, Narongpon Dumavibhat, Ponglada Subhannachart

American Journal of Public Health Research. 2018, 6(2), 117-120 doi:10.12691/ajphr-6-2-15