In south China's Guangdong Province, scorching weather caused 40 deaths early last month.
Most of the victims were construction workers, the youngest just 20 years old.
Guangzhou, which recorded temperatures over 38 degrees Celsius just three times between 1951 and 2003, has already been blasted with higher temperatures three times this month.
A dustman died of sunstroke in temperatures of 35 degrees in Ji'nan, capital of east China's Shandong Province.
Offices and most indoor workplaces now have air-conditioners, but in factories and on building sites, workers are either exposed to the elements or shut up with no ventilation all day.
Near Guangzhou, workers in clothing factories in Ruibao Village have to work long hours in damp, airless sweatshops.
"There's not even a fan in our factory, let alone an air conditioner, and sometimes we have to work for 14 hours a day," said Huang, a worker now being treated in a hospital for work-related illness.
Even in the capital city of Beijing, some workers are forced to work in unbearable weather without extra pay or precautions.
"The boss doesn't do anything to protect us from the atrocious weather," said a Tongcheng Express bicycle courier, who refused to give his name. He makes deliveries regardless of temperatures.
Unionists and work safety authorities have called on lawmakers to examine the plight of workers who are forced to work in excessive temperatures.
Wang Xiaotao, a work safety official with the All-China Federation of Trade Unions, said that there is a vacuum in the law in terms of work safety in such weather.
"Companies and organizations are required to abide by a 1960 regulation, but this is out of date," said Wang.
The existing regulation broadly states that when temperatures reach 40 degrees, laborers must be allowed to rest. But the law does not make clear what repercussions there are for companies and organizations that ignore the regulation.
"Hot weather is becoming common because of global warming and climate change," said Sun Shuhan, a professor at Renmin University. "Our responses should adapt to the trend."
The summer heat wave has hit many areas in China. Hospitals have been busy treating victims of sunstroke, dehydration, heart disease and asthma.
Guangzhou is now taking the lead in introducing a heat-warning system to help local companies and residents take precautions.
(China Daily August 10, 2004)