Dmitry Kalmykov is a Ukrainian scientist who has dedicated his life to investigating environmental disasters, first at Chornobyl and now in Semipalatinsk, Kazakhstan - formerly the Soviet Union's primary nuclear weapons testing site. Subscribe to The Guardian on YouTube ► http://bit.ly/subscribegdn He teaches schoolchildren about how bombs were tested, and how – more than 30 years after the site was decommissioned – the surrounding community is only beginning to comprehend radiation's lasting