With the onset of the smog season, air pollution levels have reached alarming proportions in Rawalpindi, Islamabad and five major cities of Punjab. The Air Quality Index (AQI) of Murree, the province's largest tourist destination, has also crossed the dangerous threshold. Due to record air pollution, Lahore, the provincial capital, has been included among the world's most polluted cities. The provincial government has decided to keep brick kilns across Punjab completely closed from November 15 to December 15. The drone-based system for monitoring smoke emissions has also proved unsuccessful. The word "smog" is a combination of two English words, smoke and fog. It refers to a thick, toxic layer formed when poisonous gases, smoke, dust and fog mix in the atmosphere. According to a survey by the Environment Protection and Climate Change Department, Lahore's overall AQI has crossed 253, while the index in several areas of the city has exceeded 419. Nankana Sahib has recorded an extremely dangerous AQI of 371, Faisalabad 290, Rawalpindi 185 and Islamabad between 170 and 172. The AQI in Murree has crossed 129, while Gujranwala has recorded 255 and Multan 296. The index stands at 116 in Attock, 104 in Chakwal, 156 in Jhelum and has reached 289 in Narowal. Air pollution has triggered various ailments, including problems affecting the nose, ears and throat, as well as eye irritation. Doctors have advised citizens to wear protective masks to guard against smog and recommended consuming herbal drinks, soups, broth and tea during the season. The burning of rice crop residues in Nankana Sahib and Gujranwala has also contributed to rising pollution levels. According to the Environment Protection and Climate Change Department, the smog season lasts from October to December. Air pollution is increasing due to smoke-emitting vehicles, heavy black smoke from railway engines, factories and industrial units, the burning of scrap and garbage, and particularly emissions from brick kilns and stone-crushing plants. Burning old and unserviceable vehicle tyres and plastic to extract black oil is also contributing to the problem. Operations against smoke-emitting vehicles, scrap, garbage, tyres and the burning of crop residues have failed to produce the desired results. Despite challans and fines, the problem cannot be controlled unless these materials are disposed of through scientific methods, officials said. Rawalpindi Deputy Commissioner Nadeem Nasir has ordered action, registration of FIRs and heavy fines against smoke-emitting vehicles, factories, industrial units, brick kilns, stone-crushing plants and those involved in burning tyres and garbage across the district. The Regional Transport Authority secretary said 49 smoke-emitting vehicles had been impounded and fines amounting to Rs600,000 imposed. A spokesperson for the Environment Protection and Climate Change Department said 21 brick kilns and five stone-crushing plants emitting smoke had been sealed. Meanwhile, officials of the relevant departments have started praying for heavy rainfall to control smog. The Agriculture Department will arrange Salat-i-Istisqa (prayer for rain) next Friday.