It took just 15 minutes for Dawn Sturgess to fall ill after coming into contact with Novichok, the inquiry has heard.
A police interview with Charlie Rowley was read out at the Dawn Sturgess Public Inquiry on October 16.
In the interview, Charlie described the moment he, and Ms Sturgess, came into contact with what was later discovered to be Novichok.
After the pair 'forced' the bottle open with a knife and spilt the substance inside it, Charlie said: "I sniffed it, but it didn't smell like perfume. I sniffed my hands, but did not get any on my nose, but it touched my skin, it was just an oily substance.
"I can't remember what it smelt like. It wasn't a horrible odour, but not like something I had smelt before. I thought 'that's not right'.
"I was quite covered in it so I had to wash my hands. I put the bottle straight back on the windowsill and I washed my hands straight away"
After Dawn sprayed it on her wrists and rubbed them together, Charlie recalled how she said she did not feel well.
READ MORE: Charlie Rowley struggled to remember Dawn Sturgess initially after Novichok poisoning
He said: "Then she said she felt very, very strange and that she had to go and lie in the bath, which I thought was a bit strange."
This was just 10 to 15 minutes after spraying it, the inquiry heard. Charlie phoned for an ambulance at 10.14am.
READ MORE: Dawn Sturgess Inquiry: Police apologise for 'overdose' claim
He said: "After a minute I went into the bathroom to see what she was doing and I found her lying in the bath with her clothes on, just lying in the bath convulsing and foaming at the mouth and I panicked. I didn't know what to do.
"I was thinking ‘what do I do, what do I do’, the only thing I could think was to call 999, I did that and had a complete memory blank."
He continued: "It felt like the whole time she was getting worse and worse and worse, to the point she stopped breathing and was trying to breathe and then I had to pull her out of the bath."
On the phone to the ambulance service, he was told how to give CPR and mouth-to-mouth until the paramedics arrived.
"I couldn't watch, I didn't know what to do, whether to pack bag and I felt helpless and shortly after this Sam [Hobson] turned up and Dawn left in an ambulance", he said.
Dawn left the scene in an ambulance at 11.50am.
Charlie did not fall ill until later that day after attending a fete organised by the Baptist Church on Raleigh Crescent Green.
In the evening, Charlie began feeling very unwell and appeared sweaty. He used the shower, spent 20 minutes in his bedroom, and then went to rest on the sofa in the living room.
Sam recalls that Charlie was 'behaving very strangely'.
Around 6.30pm, Sam called the South West Ambulance Service to report Charlie Rowley's condition.
In a statement submitted to the inquiry, Charlie said: "I have been thinking about why my symptoms took much longer to come on than Dawn's did.
"As I have said previously, I washed the Novichok off my hands very quickly, using soap and water. Dawn did not do so.
'I smoked a half- used cigarette, and it could be that Dawn was holding that when she sprayed the Novichok on her. I used the tap that I had used earlier just after I got Novichok on my hands.
"I may have touched one of the places where the Novichok had been left when I spilled it, or when Dawn sprayed it, or otherwise.'"
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules here