New Delhi, March 14 : The Swiss firm IQAir in its 'World Air Quality Report' released on Tuesday ranked India the world's eighth most polluted country in 2022, dropping from fifth place the previous year. In the list of most polluted cities in the world, out of the 50 cities, 39 are in India. Chad, Iraq, Pakistan, Bahrain, Bangladesh, Burkina Faso, Kuwait, India, Egypt and Tajikistan were the top 10 most polluted countries while Australia, Estonia, Finland, Grenada, Iceland, and New Zealand met the World Health Organization (WHO) PM2.5 guideline (annual average of 5 Aug/m3 or less). The data from 131 countries was taken from over 30,000 ground-based monitors, either government or non-government operated. As per the report, In India, the transportation sector causes 20-35 per cent of the PM2.5 pollution while other sources of pollution are industrial units, coal-fired power plants and biomass burning. After the two top most-polluted cities, Lahore in Pakistan and Hotan in China, Rajasthan's Bhiwadi is in third place and Delhi ranked fourth. Delhi's PM2.5 level is almost 20 times the safe limit, the report stated. Delhi has so far been the most polluted capital in the world and the report made a distinction between 'greater' Delhi and New Delhi the capital. Both are in the top 10 and the infamous distinction of being the world's most polluted capital goes to Chad's N'Djamena. National Capital's peripherals-- Noida, Ghaziabad, Gurugram and Faridabad have seen a decline in pollution levels. The report said that there is a 34 per cent decline in Gurugram to 21 per cent in Faridabad if compared to the average PM2.5 levels reported in previous years. Delhi has seen a decline of eight per cent. The report said that worldwide, poor air quality accounts for 93 billion days lived with illness and over six million deaths each year. "The total economic cost equates to over $8 trillion dollars, surpassing 6.1 per cent of the global annual GDP. Exposure to air pollution causes and aggravates several health conditions which include, but are not limited to, asthma, cancer, lung illnesses, heart disease, and premature mortality," the report said. According to the report, 31 cities including 10 cities in Uttar Pradesh and seven in Haryana, have seen a steep percentage decline in pollution levels. "A total of 38 cities and towns have seen a rise in pollution compared to an average of previous years," stated the report. As per the report, among the six metro cities, Kolkata was ranked the most polluted after Delhi. However, Chennai was stated to be the cleanest with pollution 'just' 5x the WHO's safe level. The metro cities -- Hyderabad and Bengalurua -- saw pollution levels uptick over the average since 2017. /IANS