Air quality in Tel Aviv and Jaffa has followed a positive trend of recent years and continued to improve through 2008, according to a recently released report by the Authority for Environmental Quality. However, the authority found that the progress appeared to be leveling off, with more significant improvements marked in previous years than in the last one, reports www.local.co.il. According to the report, the authority gathers its data from 12 monitoring stations placed above buildings that measure the air around them at various heights for chemicals commonly released by vehicles, such as nitrogen oxide and dioxide, sulfur dioxide, carbon dioxide, particles and ozone. The report said that there was a 20 percent fall in the number of days considered "polluted" in Tel Aviv last year, with 36 such days in 2008 compared with 45 in 2007. It found that the city was continuing the trend of recent years of having fewer breaches of emissions standards and lower levels of airborne chemicals.