There would have been at least seven premature deaths in Hong Kong yesterday as a result of the chronic air pollution, according to the Hedley Environmental Index which measures the impact of the city's bad air.
This compares with a reading of 2.5 deaths on a 'normal' day.
The index was developed by Professor Anthony Hedley, of the University of Hong Kong, who is a fierce critic of the government's methods of measuring pollution.
Last night, the index showed 57 premature deaths so far this month from pollution and 177 for the year.
The surge in air pollution yesterday hit the elderly badly and doctors also reported many patients complaining of breathing problems.
As of 6pm, 1,568 elderly people had sought help from the Senior Citizen Home Safety Association by pressing alarms installed in their homes. A total of 112 were admitted to hospital with 27 of these suffering from shortness of breath.
'So many patients called my clinic in the morning that I was unable to call my nurses,' Alfred Tam Yat-cheung, who is also the chairman of the Hong Kong Asthma Society, said.
Tam said with the air pollution being five times the normal level 'even healthy people may have windpipe inflammation'.
He recommended turning on an air purifier at home rather than an air conditioner. 'Air conditioners just circulate the indoor air without any purifying effect.'
And wearing a mask is not much help either, unless you wear the N95 type, according to David Hui Shu-cheong, professor of respiratory medicine at Chinese University.
A study by the university showed that while the N95 mask can shut off 100 units of dust in the air, a normal surgical mask can shut off only three units. Wearing five layers of mask would only increase the effectiveness to five units, he said.
The other downside is that you can't wear a N95 mask for more than two hours as this will cause headaches and dizziness due to a lack of airflow.
Hui said the pollutants in the air included ozone and nitrogen composites which can narrow or block the trachea and also cause inflammation to the eyes.
Doctors said chronically ill patients and people who have asthma should stay indoors over the next two days. Even healthy people should keep their windows shut at home and avoid going to places where air pollution is serious, such as Mong Kok, Causeway Bay and Tsuen Wan.