KYIV, April 16 – Kyiv has briefly become the world’s most polluted city on Thursday after new fires broke out in the radiation-contaminated areas around the defunct Chornobyl nuclear power plant, according to a report by IQAir.

Kyiv’s pollution index rose to 380, the highest indicator among 100 cities in the world tracked by IQAir, followed by two Chinese cities of Shenyang and Chengdu with scores of 180 and 171, respectively.

Kyiv’s index dropped to 157, the second highest position, in early hours of Friday, indicating a moderate progress that has been made by more than 1,000 Ukrainian firefighters sent to the exclusion zone to extinguish the fires.

Meanwhile, Ukrainian officials downplayed the scale of the fires, saying the three fires they were "not large-scale and not threatening.” Gusty winds fanning the flames have made it harder to put them out.

Volodymyr Demchuk, director of the Emergency Response Department, said in a video statement the “radioactive background” in Kyiv and the Kyiv region “is within normal limits," RFE/RL reported.

Emergency workers aided by rain on April 14 were able to extinguish wildfires burning in the forests near the plant, which has a structure covering its destroyed section.

The earlier fires began on April 3 in the western part of the uninhabited exclusion zone and spread into the forest. They posed no threat to facilities holding radioactive waste, the emergency service said in a statement.

Environmental experts feared that the fires could stir up radioactive ash in the ground, potentially blowing contamination-laden smoke into Kyiv, about 100 kilometers to the north.

Emergency workers used planes and helicopters to help put out the fires earlier this week, but heavy winds prevented them from doing so on April 16, Deputy Interior Minister Anton Gerashchenko was quoted by the Interfax news agency as saying.

The reactor meltdown and explosion at the Chornobyl plant in 1986 sent clouds of nuclear material across much of Europe. It is considered the worst nuclear disaster in history. (tl/rfe/ez)