The worsening ecological situation in the Russian capital prompted several countries to evacuate their embassy staff from Moscow, while other states recommended their nationals to abstain from visits to Russia, RIA Novosti reported.
Austria, Poland and Canada have evacuated some of their non-essential embassy employees and their families, while Germany temporarily closed the embassy and the consular department, the Ekho Moskvy radio station reported.
Moscow has been hit by smog from nearby peat bog and forest fires mixed with pollutants for much of the last 12 days. The fires have been caused by a heat wave that has seen temperatures more than 40 degrees Celsius (104 degrees Fahrenheit).
On Saturday Moscow saw its worst air pollution in 2010, with carbon monoxide levels being 6.5 times more than maximum allowable concentrations. The concentration of other poisonous substances in the city air was nine times above the norm.
Earlier in the day, the U.S. has warned Americans to "carefully consider" the risks involved in travel to parts of Russia.
The U.K. Foreign Office has also advised "against all travel to specific regions of Russia, and against all but essential travel to other specific regions of Russia."
France, Bulgaria and Germany also cautioned their citizens against travelling to Moscow and other disaster-hit areas in Russia.