MUMBAI, Nov. 13 -- Two workers hired to clean the sewage treatment plant (STP)-linked tank filled with sludge in a Powai building suffocated on Wednesday, leaving one Akshay Mandal, 22, dead, and the other, Phulchand Kumar Sahu, 27, critical in the ICU. While the fire brigade claimed the workers suffocated due to a lack of oxygen in the enclosed space, the BMC's press note claimed that inhalation of toxic gases was the culprit. No safety equipment was given to the workers, employed by Ultra Tech Pvt Ltd at the Raj Grandeur building in Powai. "Three migrant workers--Akshay Mandal, Phulchand Kumar Sahu, and Sudam Mandal, 22--were called to clean the septic tank at around 9am," said Shubham Kothari from the Loktantrik Kamgar Union which works for sanitation worker rights. "The workers requested a ladder to get down into the seven-foot-deep tank, but denied this, they used ropes. No PPE or safety gear for such hazardous cleaning were provided by the company." Kothari said that Sudam and Akshay ventured in first. "After 30 minutes of cleaning, both felt suffocated, and called out for help, " he said. "With no ladder available, it was hard for them to get out. Helped by Phulchand, Sudam was able to come out, collapsing immediately. To get Akshay out, Phulchand then ventured into the tank, only to collapse too."A call was then made to the fire brigade at 10:42 am, by Raj Grandeur's security guard as per Kothari. "The Vikhroli fire brigade arrived within six minutes," said Vishnu Awhad, senior station officer, Vikhroli. "It was called by the workers' supervisor who noticed that there was no noise or movement from the tank after a while. We donned breathing apparatus, went in and got both of them out." Both Phulchand and Akshay were then taken to Hiranandani Hospital next door. Awhad explained that the STP apparatus was linked to the tank, in which sludge had collected over time after chemicals were used to treat the sewage. "This was routine cleaning work done every 6 months or so," he said. "This was not technically a septic tank; the workers suffocated due to lack of oxygen, not poisonous gases. When workers are made to go into a confined space, safety regulations must be followed, which include removing the gases enclosed, testing the gas composition, and giving safety equipment." The Powai police station have registered an accidental death report. To this, the union demanded that an FIR be filed as per the Prohibition of the Manual Scavengers Act, 2013, and the three workers be compensated. "Criminal action should be taken against the housing society chairperson and owner of Ultra Tech Pvt Ltd, which employed workers as manual scavengers regularly," added the union. Ultra Tech Pvt Ltd did not get back with a response, nor did a member of the building's managing committee. The S ward's assistant commissioner, Mahesh Patil, did not respond....