It remains unclear what exposure the pair suffered on Wednesday afternoon, with police yet to confirm whether it was related to drug production.

"About 2.40pm police were called to an industrial unit on Dallinger Road in Lavington, in response to a male and female experiencing breathing difficulties," a spokeswoman said.

"The male and female in their 30s were taken to hospital in a serious condition."

The spokeswoman said the cause of the exposure was undetermined and did not address unconfirmed reports of drug production at the unit.

"Officers from Murray River Police District attended and commenced inquiries.

"Police seized cannabis plants, prohibited drugs and weapons.

"These items will undergo forensic analysis."

Fire and Rescue NSW units and multiple ambulances remained on scene for more than three hours.

Leasees were prevented from getting into their units with the entire area cordoned off.

One person working nearby on Wednesday told The Border Mail he was not aware of what the unit was leased for or the nature of the incident.

Inspector Steve Perkins led the response for Fire Rescue NSW on Wednesday and said three units with hazmat capabilities responded.

"Brigades were called to a premises in Lavington and they arrived to find two persons who had been affected by a chemical, being attended to by ambulance," he said.

"A third person was treated by fire brigade personnel until more ambulances arrived.

"Two firefighters in hazmat clothing searched the premises looking for chemicals and declared the atmosphere safe.

IN OTHER NEWS:

"The premises was then handed over to police and is an ongoing investigation."

There are multiple individual industrial units/garages behind businesses in the Dallinger Commercial complex.

Anyone with information about the incident is urged to contact Crime Stoppers on 1800 333 000.