Greenpeace on Wednesday urged the government to implement laws to protect workers from heat stroke before next summer, saying the current three-tier warning system is ineffective.

After surveying more than 120 construction workers and street cleaners in August, Greenpeace and the Hong Kong Catholic Commission for Labour Affairs reported that over 60 percent of interviewees had experienced symptoms of heat illness during work, including physical exhaustion, asthma, and accelerated heart rate.

The groups also said more than 40 percent of the respondents did not receive additional rest time even if heat warnings were issued.

The government's three-tier warning system – enacted in May – advises employers to take measures to prevent workers from getting heatstroke if the warnings are issued.

“The guidelines are not really effective right now,” Greenpeace campaigner Tom Ng said, adding that it would be beneficial to workers if they were legally binding.

“In our findings, we find that there is only one anti-heatstroke measure, which is providing drinking water. It is the only measure that over 50 percent of the workers receive. All others are less than 50 percent,” Ng said.

He added that providing drinking water is the only measure that is written into law.

“The government should immediately talk with the frontline workers and worker unions to review and create new, better, more feasible guidelines for the workers next year before the summertime,” he said.

Looking ahead, Ng said the government should also add heat stroke and other heat-related diseases to the list of occupational diseases.

Last month, the Labour Department said the government heat stress index accurately reflects the level of heat stress and associated health risks.