The city along with winter chill in January also witnessed high concentration of fine particulate matter less than 2.5 microns which crossed permissible levels, say scientists from the Indian Institute of Tropical Meteorology (IITM). They said the quality of air is very poor. Levels of PM 2.5 have touched 135 micro gram per meter cube and this can be harmful to health as the microscopic dust can penetrate into the deepest recesses of lungs, say IITM scientists. In fact, such is the rise that the scientists have measured an increase of as much as 273 per cent in the PM 2.5 level from September last year. Dr Gufran Beig, scientist at IITM who monitored the air quality levels, said Pune has crossed the permissible level of 60 micro gram per meter cube of PM 2.5. Last December had seen levels up to 89 microgram per meter cube. Not just PM 2.5 levels but there was an increase of 374 per cent in levels of Nox (nitrogen oxides) in January this year as against last September, says Beig. According to Beig, the reason for the increase in the microscopic particles of dust is due to temperature inversion and lowering of boundary layer. Pollutants are trapped in these layers and can no longer be lifted from the surface, he explained. If the weather continues to be cold, the level of pollution, especially the PM 2.5 microns, can increase, he added. Short exposures of these levels can produce coughing, irritation and bronchial inflammation, Beig said. Mangesh Dighe, environmental officer with Pune Municipal Corporation, said particulate matter rises because of distortion of weather conditions. Winds are strong in summer which wipe away the dust and pollution, he said. Officials at the Maharashtra Pollution Control Board (MPCB) which continuously monitors pollution levels say that there is a rise in respirable suspended particulate matter during winter. However, officials still have to analyse the data for last three months, P K Mirashe, western region officer of MPCB, said. Deterioration of air quality results in increase in health problems and according to Dr A Shahade, president of the city unit of Indian Medical Association, there have been cases of prolonged illnesses with recurrent bouts of cough and burning of eyes. Dr Barnali Bhattacharya, member of the Indian Academy of Paediatrics, too pointed out that there is a rise in the number of cases of respiratory ailments during winter and pollution contributes to this problem.