The black snow in Omsk also appeared twice in December, and was likely caused by a local thermal power station, TPP-5, that was working at overload capacity, Rosprirodnadzor told RIA Novosti.
"Work is under way. According to preliminary reports, this is again TPP-5 that has dumped ash. By Monday, the samples will be examined," a spokesman for the organization said.
The plant had said that it would replace a filter for one of its tubes to fix the problem. The filter was expected to cost $4.3 million.