Task: Explanation
Input (English): Paragraph: The Air Visual API website, which compiles data from ground sensors worldwide, ranked the Serbian capital temporarily at the top of its global index of cities with the worst air pollution. Belgrade’s pollution level later fell to fourth, behind Ulaanbaatar in Mongolia, Zagreb in Croatia, and Chiang Mai in Thailand. Local researchers say that domestic heating and industry, including decades-old coal-fired power plants which provide most of Serbia’s energy, emit almost three-quarters of the country’s polluting air particles. In January hundreds of protesters took to Belgrade’s streets    demanding the government tackle severe air pollution throughout the European Union candidate country. In a statement, Ne Davimo Beograd (Let’s Not Drown Belgrade), a local rights and environment watchdog, said that the main cause of the latest pollution could be a smouldering fire at the sprawling Vinca landfill, about 20 km (12 miles) east of the city center. Radomir Lazovic, one of the organization’s leading activists, said that air pollution could aggravate the condition of people with pulmonary diseases, which are particularly susceptible to coronavirus infection. “According to estimates ... (by doctors), there are around 1 million of these people in Serbia,” Lazovic told Reuters. In a statement, the ministry for environmental protection said that along with small heating plants and domestic heating, dust was the main contributor to most recent pollution. “After melting of snow and drying of the surface (soil), a strong wind led to re-emission of the (dust) particles into ... the lower layers of atmosphere,” the ministry said. So far, the coronavirus infection in Serbia has sickened 528 and killed eight people. Officials from Belgrade’s waste disposal company and city hall who are responsible for the landfill could not immediately be reached for comment. Claim: World's worst air adds to Serbian capital's coronavirus woes.
Output (English): Belgrade’s residents on Friday isolated themselves not only from coronavirus but also from acrid smoke, which defied strong winds to transform the Serbian capital into the city with the world’s most polluted air.