The 60-year-old had seen his father Basil’s life ebb away from severe lung disease after years of smoking a pipe and Peter, from Bedhampton, did not want to go the same way.
With the help of the smoking cessation service at Bosmere Medical Centre grandfather Mr Irish managed to give up his 45-year, 20-a-day habit.
As part of the service patients blow into a carbon monoxide monitor to check how much of the poisonous gas found in tobacco smoke they have in their system.
A healthy reading is between three and five parts per million in breath (bpp) but he was stunned when his carbon monoxide readings continued to go up after he’d given up.
His nurse suggested he buy a carbon monoxide alarm and within minutes of installing it at home it went off.
Mr Irish, a business development manager, said: ‘My dad has recently died from chronic obstructive pulmonary disease.
‘With him being so ill, and me about to reach 60, I thought this was the time to give up smoking.
‘The first time I blew into the carbon monoxide machine – having given up three weeks earlier – the reading was eight.
‘The next time it was 10 and the third time 16. I was stunned because I hadn’t been smoking.
‘That’s when they suggested I check my appliances for carbon monoxide.’
Mr Irish immediately bought a carbon monoxide detector.
That evening, within 30 minutes of putting his gas fire on, the alarm went off.
Mr Irish said: ‘We called the gas company out and they said none of the gas was being released up the chimney and it was a wonder we weren’t dead.
‘We then had the chimney swept and they found a huge bird’s nest.
‘If I hadn’t bought the carbon monoxide tester my wife Julie and I could have fallen asleep on the sofa watching television and not woken up.’
Since Mr Irish’s chimney was swept his carbon monoxide readings have gone down to a healthy three.
He says: ‘I’m very grateful that no one else was harmed.
‘You would not think a bird’s nest could kill.’
Three months since smoking his last cigarette Mr Irish said: ‘Giving up smoking has saved my life twice.
‘If I hadn’t given up smoking we would never even have considered carbon monoxide poisoning.
‘And I feel fantastic now.
‘I go to the gym and can do so much more.’
Sarah Hill, from the Gas Safe Register, said Mr Irish and his family had a lucky escape but said carbon monoxide alarms should not be a substitute for yearly gas safety checks on all gas appliances.
She added: ‘Carbon monoxide is a killer.
‘You can’t see it, you can’t smell it and you can’t taste it. You would not know it was there.
‘It can cause headaches, dizziness, nausea, breathlessness, collapse and lead to falling unconscious.
‘That is why gas safety checks are so important.’