From the website of the company that runs the facility (http://www.npoenergomash...

njs12345 on Jan 7, 2012 | parent | context | favorite | on: This Girl Snuck Into a Russian Military Rocket Fac...

From the website of the company that runs the facility (http://www.npoenergomash.ru/eng/) it would seem most of the tests are of engines which use a liquid oxygen/kerosene mixture - presumably not much more toxic than exhaust from cars..