Toxic haze blanketed Sydney yesterday triggering a chorus of smoke alarms to ring across the city and forcing school children inside, as “severe” weather conditions fuelled deadly bush blazes along Australia’s east coast. Fire engines raced office-to-office in the city centre with sirens blaring, as inland bushfires poured smoke laden with toxic particles into commercial buildings. For weeks the east of the country has been smothered in smoke as drought and climate-fuelled bushfires have burned. But the scale of the problem on Tuesday shocked even hardened residents. Authorities recommended that the vulnerable cease outdoor activity altogether and that everyone stay inside as much as possible. As the day developed there were nearly 100 bushfire incidents in the state of New South Wales alone and dozens more in Queensland.