MOSCOW - The Russian Emergency Situations Ministry claimed credit for a light drizzle that cleared the air over the Russian capital Friday, giving residents a break from the thick, acrid smog that engulfed the city.

"Yes, we did it," ministry spokesman Viktor Beltsov said proudly.

Beltsov said an ionizer intended to draw rain clouds was switched on Thursday atop a ministry building in western Moscow and it did the job. Early Friday, a light drizzle freshened up the air, bringing long-sought relief after several rainless weeks. Wildfires in the countryside surrounding the capital have created intense smog.

Beltsov said the ministry kept the device working Friday in an effort to attract more rain. It was the first time the ministry used the equipment, developed by its research institute, Beltsov said.

The institute's director, Mikhail Shakhramanian, said on ORT television Thursday that the device, a metal cage crisscrossed by tungsten wire, emits a vertical flow of oxygen ions that stirs the air and raises humidity.

Meteorologists warned that more substantial, genuine rain would be needed to put out the forest and peat bog fires blazing around Moscow. The weather was expected to remain dry over the weekend, but rains were forecast for early next week.

Ironically, the city government did everything it could over the weekend to prevent a downpour. Cloud-seeding planes were used to disperse any potential rain that might have disrupted City Day celebrations.

The smog that hung over the city through much of the summer peaked Thursday, cutting visibility to just hundreds of meters (yards), slowing traffic to a crawl and suspending flights at some Moscow airports. On their way to work, Muscovites coughed as they inhaled the smoke that shrouded buildings and even filled subway stations.

Despite the drizzle, the carbon monoxide level in Moscow was more than twice admissible levels Friday, the Emergency Situations Ministry said.

Doctors suggested people stay indoors if possible, and some schools canceled classes Friday.

According to the ministry, fires covered 537 hectares (1,326 acres) around the capital as of early Friday, many of them below ground in smoldering peat bogs. Firefighting efforts involved 3,500 people and four aircraft, which dropped 500 metric tons (550 tons) of water, the ministry said.

The area around Moscow has registered its lowest rainfall in a century, Russian media reported, and the smog was the worst the city had seen in 30 years.

Smog also enveloped other Russian cities, including St. Petersburg, where emergency workers fought more than 240 fires in the surrounding region.

The haze from the fires reached southeastern Finland and southern Sweden Thursday. The Swedish weather service said smoke particles reduced sunlight by up to 60 percent until a cold front from southwest cleared the air late Thursday.