Workers employed to the Central Sorting Office (CSO) in Kingston were again sent home yesterday after complaining that they were still suffering from the lingering effects of the noxious gas that caused many to faint on Thursday.

Health ministry officials yesterday advised that the employees be sent home after assessing the situation.

At least 60 people had to be rushed to hospital for treatment on Thursday after inhaling the fumes.

Peter Knight, CEO of the National Environment and Planning Agency (NEPA), said yesterday that he had not determined the source of the gas that engulfed the CSO.

"We have some general scenarios that we are looking at now, we have also expanded the team today (yesterday) and have brought in some additional skills to cover more ground," Knight told The Gleaner.

"There is a particular chemical that we have narrowed the scenario down to; we currently have persons in the office who are doing some investigations on this. The team has also done some extensive work and has carried out checks on several premises in the area," he added.

"When I came in this morning (yesterday) at about 7:30, members of staff indicated that they were still not feeling well. I called in NEPA and the MOH. They came in and did checks and didn't find anything but we decided to send them home as a precautionary measure," Michael Gentles, Jamaica's postmaster general, told The Gleaner.

"Over the weekend, we will set up some work teams to make sure that the entire building is properly ventilated. We have also requested for the MOH and NEPA to come in on Monday morning at 8 o'clock to do some additional checks and testing," he added.