Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Serial radiographs of coal miners with PMF identified in the National Institute for Occupational Safety and Health-administered Coal Workers’ Health Surveillance Program for the period 2000–2016. N is total number of radiographs, n is number of radiographs with an initial small opacity profusion category 0, mean and medians are time from major ILO category 0 to PMF in years. ILO, International Labour Office; PMF, progressive massive fibrosis.
