(AGI) Tehran, Dec 30 - A total of 392 people have been admittedto hospital for breathing and heart problems due to Tehran'svery high level of air pollution. Another 1,434 people havebeen treated but then sent home because their symptoms wereless severe. Twelve million people live in Tehran and there aremore than four million cars are on the roads, most of which arenot in line with stringent European standards. Also, althoughIran is one of the largest oil producers it has poor qualityfuel due to the lack of modern refineries because ofinternational sanctions. The situation is worse in winter whena carcinogenic smog cloaks the city, a mix of harmful carbonmonoxide, sulfur dioxide, nitrogen oxide and particulates(mainly diesel residues). The city also tends to pollutionbecause it is at an altitude of between 1,100 and 1,700 metresabove sea level and this favours the formation of thephenomenon of thermal inversion where cooler air is trappedlower down and thus has little chance of exchange with thewarmer air above. The latest complete figures on the impact ofpollution from the Ministry of Health date back to 2012 whenthere were 4,500 deaths from pollution in Tehran alone andabout 80,0000 in the whole country. (AGI).