Blue snow could be seen falling in several districts in the Russian city of St. Petersburg late Tuesday.
Many residents reported the unusual weather phenomenon on social media with most expressing their fears about the snow, which could be contaminated with toxins.
Russia's environmental monitoring agency officials took samples to examine the blue snow following numerous complaints.
The officials said most of the snow had a light blue color, but some of the snow was also violet.
Locals believe the snow's unusual color could be a result of demolition of the city's chemical-pharmaceutical research institute located near the districts the snow was sighted in.
The affected areas received about 1 centimeter (0.39 inches) of the blue snow.
In February 2015, blue snow was sighted in the Russian city of Chelyabinsk. Official investigation found that the reason for the blue snow in Chelyabinsk was food coloring used for Easter eggs, which accidentally got into the ventilation system of the factory and was dispersed in the area.
