Weather awareness: Hong Kong Observatory Director Dr Lee Boon-ying (centre) releases the findings of a study on the impact weather has on the elderly.

A Hong Kong Observatory and Senior Citizen Home Safety Association joint study has found dry and cold weather has a particularly significant health impact on the elderly.

The study analysed the daily number of people activating the association's Personal Emergency Link Service and requiring subsequent hospitalisation as well as the weather data from 2004 to 2008. The results released today showed air temperature and relative humidity affect seniors' health.

The study recorded a high number of hospitalised people on about half of the cold and dry days with the relative humidity at 70% or below.

When the minimum temperature was below 22 degrees Celsius, the number of hospitalised people also rose. The figures were more than 10% higher when the temperature fell below 12 degrees.

Hot temperatures also affected the elderly. When the maximum temperature was higher than 30 degrees, the number of hospitalised people surged as temperatures rose. The figures were more than 7% higher when temperatures reached 34 degrees or more.

As winter approaches, the Observatory will remind the 70,000 users of the association's Personal Emergency Link Service to prepare for the cold weather through the Caring Message Service.