SYDNEY • Sydney was shrouded in dangerous haze yesterday as smoke from bush fires blazing along Australia's eastern seaboard sent pollution levels soaring in the country's biggest city.
Official data showed that pollution had reached hazardous levels across Sydney, with the highest readings of PM2.5 particulates in the city's north-west reaching 186 parts per million on the air quality index - comparable with Delhi - and residents warned to avoid outdoor exercise.
The usually blue skies of the harbour city turned a miserable grey, with world-famous landmarks such as the Sydney Opera House and the Sydney Harbour Bridge dulled against the skyline.
Although the smog had begun to ease under the midday sun, it increased again yesterday evening, the Bureau of Meteorology said.
"Sydney is also known as the 'big smoke' and is living up to the nickname today," the weather forecaster tweeted.
New South Wales state environmental health director Richard Broome said the fine particles in smoke could irritate people's respiratory system and aggravate existing lung and heart conditions.
"For most people, smoke causes mild symptoms like sore eyes, nose and throat," he said.
"However, people with conditions like asthma, emphysema and angina are more likely to be sensitive to the health effects of smoke."
Much of the smoke is being blown from a huge out-of-control bush fire spreading across two national parks that is just 100km north-west of central Sydney at its closest point.
The blaze, which has been raging for several days, has already burned through almost 140,000ha of bushland.
Six people have been killed and hundreds of homes destroyed in bush fires across New South Wales and Queensland since September, when an unusually early fire season began across drought-stricken regions in the east of the country.
Cooler weather brought some respite for firefighters in recent days, but higher temperatures, gusting winds and low humidity are expected to raise the bush fire threat again today.
More than 110 fires are currently burning across Australia's east, with dozens of the blazes still uncontained.