Norwich was among the cities covered in smog this morning as health experts warn those with heart and lung conditions, including asthma, to avoid strenuous activity outdoors.
People suffering symptoms of pollution - including sore eyes, coughs and sore throats - should also cut down the amount they do outside, experts said.
Higher numbers of complaints about breathing difficulties are thought to have been brought on by record pollution levels in recent days.
Air pollution in the east of England reached the top of the scale as a 'perfect storm' of conditions blanketed parts of the country.
Our region is one of the worst-affected by "very high" levels of air pollution today, with much of the East stuck under a cloud of smog.