Medicals experts in Shanghai have reminded the public to take necessary precautions against the ongoing heat wave which has resulted in an increase of patients seeking medical attention and even deaths compared with last year.

Shanghai is one of the cities most affected by the ongoing heat wave that has engulfed much of the country. While the city has yet to enter sanfu, which refers to three 10-day periods with the hottest days of the year, the mercury has already been over 40 C for three straight days.

"According to information submitted by major medical institutions across the city, there has been a significant increase in heat stroke cases," Xu Huihui, director of environmental health department under Shanghai Disease Control and Prevention Center, told ThePaper.cn.

"There have also been reports of deaths from thermoplegia, the most severe form of heat stroke."

Xu noted that it is unusual to see so many cases of heat strokes before sanfu, which is slated to begin on Saturday.

The elderly, Xu added, are more susceptible to heat strokes because their skin are less sensitive to the heat.

"When the room temperature is higher than 32 C, electric fans don't help much. It'd better to keep the air conditioners running in hot weather especially when the air temperature hits 40 C," he said.

Xu also suggested that those who develop symptoms such as fatigue, dizziness, an inability to concentrate and accelerated heart rate to immediately stop what they are doing and rest.

"By the time a heat stroke develops into thermoplegia, the window for rescue is just half an hour before the condition becomes fatal," Xu said.