New Delhi suffered a rare summer air pollution alert yesterday as dust storms and heat over northern India took smog to hazardous levels. The world’s most polluted capital city is blanketed in a toxic smog of car fumes, agricultural smoke and factory waste most winters, but it is less severe in summer months. Yesterday, the Indian government’s air quality index hit “very poor” with PM 2.5 particles, the most harmful, at 154 micrograms per cubic metre, five times the normal safe level. Clouds of dust swirled around the streets and many people brought out masks generally used in winter. “Right now we are in the thunderstorm season. High speed winds are raising a lot of dust but we think it is only transient and will change in a day or two, when it rains,” V.K Soni, an India Meteorological Department official, told AFP.