Just days before the Olympic Games are due to begin, the benchmark air pollution index reached an unprecedented 202 in Tap Mun - one notch higher than the previous record of 201 set in 2005 at Tung Chung.

Temperatures soared to 36 degrees Celsius in many areas and at least 91 elderly people were taken to hospital with respiratory problems. A further 1,334 needed emergency help.

Senior citizens' groups said the elderly had borne the brunt as Kowloon City, Sha Tin, Tuen Mun, Sai Kung and Shau Kei Wan sizzled in the heat and high pollution.

The government confirmed last night that a 52-year-old Sha Tin woman had died of suspected heatstroke in the afternoon after being taken to Prince of Wales Hospital.

Another man suffered heatstroke and was in a stable condition in Kwong Wah Hospital last night. A postman in Fan Ling was also overcome by the heat.

The Hong Kong Observatory's principal environmental officer, Dave Ho Tak-yin, confirmed yesterday's API was the highest recorded since air quality monitoring was introduced in 1995.

He blamed the influence of high air circulation from Typhoon Fung- wong, which hit Taiwan yesterday.

Dutch Olympic soccer coach Foppe de Haan described the smog as "awful" as his team prepared in Hong Kong for the Olympic Games.

De Haan said his side had trained in a special gym back home to prepare them for the hot and humid conditions in Hong Kong and China but there was no way of replicating the smog.

As thunderstorms crossed the territory last night, the observatory's senior scientific officer, Tsui Kit-chi, said it would be mainly cloudy with showers today, which will likely blow the pollutants away.

Yesterday territorywide air pollution levels ranged from "high to "severe."

The API at Tap Mun reached a "severe" 202 at 3pm while in Sha Tin, where the Olympic equestrian events will be held, it hit a peak of 173 at 2pm before dropping off.

An Equestrian Company spokesman said the high levels of pollution and temperature had not affected the horses and there had been no complaints from athletes. Vets carried out checkups on horses and there was no cause for alarm, he said.

The horses received training in the morning and were kept in air- conditioned stables in the afternoon.

Chief Executive Donald Tsang Yam-kuen said Hong Kong's heat is one of the challenges athletes will need to overcome.

"Athens was hot as well. They need to overcome cold as well as heat," Tsang said.

"It is part of the competition."

The Home Affairs Department last night opened 14 temporary shelters for those suffering from the heat.