Australian Open tournament director Craig Tiley has defended his decision to allow qualifying matches to continue in choking smoke haze amid simmering unrest among players.
British player Liam Broady on Thursday accused officials of treating qualifiers worse than animals in a Twitter outburst.
Broady lost in the first round of qualifying, playing his match in a blanket of smoke on Tuesday at Melbourne Park, and said he struggled to breathe in the conditions.
Slovenian Dalila Jakupovic had to quit her qualifying match that day after a coughing fit, while Australia's Bernard Tomic also sought medical treatment.
Tiley said the air quality fell under the threshold that organisers had come up with in consultation with the Environmental Protection Authority and other experts in the area, including the Australian Institute of Sport.
"Our medical team were satisfied with the conditions that the players were competing in, per all of the research and the data and the science that they have," Tiley told reporters on Thursday.
"But they also make an assessment.
"You could have been two hours into those matches and have 25 people presenting themselves with a medical condition that may be related to the pollutants.
"If that's the case, inform me and we stop."
World No.234 Broady took to Twitter, saying: "The more I think about the conditions we played in a few days ago the more it boils my blood.
"We can't let this slide. The email we received yesterday from the ATP and AO was a slap in the face, conditions were 'playable'. Were they healthy?
"Citizens of Melbourne were warned to keep their animals indoors the day I played qualifying, and yet we were expected to go outside for high intensity physical competition?"
Broady's tweet was supported by Germany's Dustin Brown, who also needed medical treatment during his first-round loss on Wednesday.
"'I have a virus coming on' I was told by the doctor on court," Brown tweeted.
"In 35 years it's the first time I had to use an asthma spray to help me breathe better #wellsaidLiam."
Former world No.25 Canadian Vasek Pospisil said the situation was "absurd" and it was "time for a players' union".
French player Alize Cornet, a former world No.11, also agreed: "We have to stick together and stop this nonsense #players union."
The tournament's air-quality policy has been hastily put together on the back of the bushfire crisis and Tiley admits it had been a tricky task to inform the players adequately on the issue.
"Absolutely, we understand the anger (but) a lot of it comes from the confusion and the complexity of understanding what goes on," he said.
"We've invited the players, as we've said to them, to come in at any time to have a conversation.
"If anyone at any time is feeling not well, we have a full medical team.
"We have a respiratory specialist on hand to deal with any of these issues."