ELEKTROGORSK, Russia  For two weeks, soldiers with chain saws felled every tree in sight.

Firefighters laid down a pipe to a nearby lake and pumped 100 gallons of water every minute, around the clock, until the surface of what is known as Fire No. 3 was a muddy expanse of charred stumps.

And still the fire burned on.

Under the surface, fire crept through a virtually impenetrable peat bog, spewing the smoke that  until the wind shifted on Thursday, providing what meteorologists said was likely to be temporary relief  had been choking the Russian capital this summer.

Among all the troubles that have been visited on Russia in this summer of record heat, wildfires, smoke and crop failure, perhaps none have been so persistent and impervious to remedy as the peat fires. Particularly maddening, many here say, is the knowledge that the problem is caused by humans.