'Smog flx must be as unique as the problem

WHEN London's Great Smog of 1952 killed over 12,000 people, the world first realised that the deadly cocktail of air pollution and weather conditions could affect public health.

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The term "smog" - a mixture of smoke and fog - entered our talks, marking the beginning of our understanding of the urban air pollution crisis. Los Angeles followed with its distinctive photochemical smog in the 1970s due to automobile emissions reacting with sunlight, creating a yellowish haze that became a sign of the city's rapid growth. But Delhi's smog, which gained global attention in 2016 when the air quality index crossed the 500 mark and schools were shut down for the first time, is a different story altogether. Unlike London's coal-driven smog or Los Angeles automotive exhaust, Delhi's severe air quality emergency is a perfect storm of multiple factors: agricultural stubble burning in neighbouring states, vehicular emissions, construction dust, industrial pollution, and calm weather conditions of winter which trap these pollutants over the city What makes Delhi's situation unique is its geography and the timing of the bad air quality episodes. Located in the Indo Gangetic plain, the city becomes a bowl of pollution during winter months especially in November, trapping pollutants under a layer of cold air which is accounted to decrease in the layer of the atmosphere closest to the Earth's surface. When this combines with the seasonal stubble burning i