Temperatures of more than 30 degrees Celsius and humidity soaring past 80 per cent have led to a string of retirements due to injury or illness in Shanghai, with defending champion Jannik Sinner the highest-profile casualty.
With players marvelling at the "brutal" conditions in post-match interviews, the body governing men's tennis, the ATP, confirmed to AFP Tuesday that it was evaluating bringing in a heat policy.
World number 11 Rune said he thought "every player would agree" that the tournament needed a rule like those in place at Grand Slams.
"We can handle a certain amount of heat, because we're strong and mentally strong as well, but there is always a limit," the Dane told reporters.
"It's also important to take care of your health. We need to survive."
Rune had to take a medical time-out in his match against Ugo Humbert on Sunday because of the heat.
Those who have dropped out due to sickness or injury so far include Casper Ruud, David Goffin, Tomas Machac, Terence Atmane, Hamad Medjedovic and Wu Yibing.
The ATP said in a statement that player safety was its top priority.
Currently, decisions affecting play to do with weather conditions, including heat, "lie with the on-site ATP Supervisor, in coordination with on-site medical teams and local authorities", it said.
Its medical services team also implements "several measures in cases of extreme heat" to protect competitors' health.
"This remains under active review and additional measures including the implementation of an official heat policy are currently being evaluated in consultation with players, tournaments, and medical experts," the statement added.