NEW DELHI: Beijing's air pollution made international news over the weekend when fine particulate matter (PM2.5) in the city air rose to an ‘out-of-index' level of 755 mg/cu m. Pictures showed Beijing residents wearing masks amid advisories that they should stay indoors. Meanwhile, it was business as usual in Delhi on Monday when despite a clear windy day, the PM2.5 levels ranged from 130 to 565 mg/cu m.According to World Health Organization, the safe level of PM2.5 is 20 mg/cu m. The Indian standard for this pollutant — that can cause respiratory illnesses and worsen heart ailments — is 60 mg/cu m.On Monday, the highest value of 565 mg/cu m — considered very hazardous — was recorded at R K Puram for about two hours. But even the lowest reading at this site was 191 mg/cu m, more than three times the Indian standard.In November 2012, when the city was in the throes of its worst smog spell in recent years, PM2.5 levels were consistently over 500 mg/cu m over several places."Beijing undertook several measures to control its air pollution levels during the Beijing Olympics in 2008 but the city is still prone to smog. More recently, it has decided to implement a lottery system for private cars which it hopes will keep a check on the rising number of vehicles. Despite all this, the city continues to battle worsening air quality," said Anumita Roychowdhury, associate director at the Centre for Science and Environment."Delhi, which is confronted with the same issues, is hardly doing anything to control air pollution. It would come as no surprise if we surpass Beijing's record in the next couple of years," Roychowdhury added.Experts say that smaller the particulate matter, the more likely it is to affect human health. Between PM10 and PM2.5, the thicker particles are most likely to be natural while smaller ones are a result of activities such as combustion. This is why, claim environmentalists, vehicles are considered a major contributor to PM2.5 levels.To understand the size of these particles, the diameter of human hair is about 50 micrometers while that of PM2.5 is 2.5 micrometers.The two most likely reasons for high levels of PM2.5 at present are vehicular emissions and biomass burning. While pollution levels are always higher in winter, Delhi's cold also leads to several small fires being lit in an effort by people to keep warm.Realizing the urgent need to tackle the city's deteriorating air quality, Delhi's environment department, with the help of other agencies, has drawn up an extensive master plan. However, while it is still to be cleared by the Delhi cabinet, all good intentions are being wasted. Not only PM2.5, levels of PM10, oxides of nitrogen and ozone are all on the rise.The city's biggest worry is its fleet of over 74 lakh vehicles to which about 1,700 are added each day. An increasing number of new vehicles are also diesel-run which makes it worse for the city's environment."We are not a dictatorship but seeing how the environment is getting degraded, the government needs to take some firm steps to control the rising number of personal vehicles in the city," said Roychowdhury.