FRONTLINE and NPR investigate the rise of severe black lung disease among coal miners, and the failure to respond. Subscribe on YouTube: bit.ly/1BycsJW This joint investigation reveals the biggest disease clusters ever documented, and how the industry and the government failed to protect miners. Also in this two-part hour, FRONTLINE presents a report from Yemen. Watch "Coal's Deadly Dust" starting January 22, 2019: www.pbs.org/wgbh/frontline/film/coals-deadly-dust/ Twitter: twitter.com/frontlinepbs Facebook: www.facebook.com/frontline Google+: plus.google.com/+frontline/posts FRONTLINE is streaming more than 200 documentaries online, for free, here: to.pbs.org/hxRvQP Funding for FRONTLINE is provided through the support of PBS viewers and by the Corporation for Public Broadcasting. Major funding for FRONTLINE is provided by the John D. and Catherine T. MacArthur Foundation and the Ford Foundation. Additional funding is provided by the Abrams Foundation, the Park Foundation, The John and Helen Glessner Family Trust, the Heising-Simons Foundation and the FRONTLINE Journalism Fund with major support from Jon and Jo Ann Hagler on behalf of the Jon L. Hagler Foundation.