A mother has warned it is only a matter of time before a child dies - after her son developed the tell-tale symptoms of lymphoma when their car began leaking deadly exhaust fumes. 

Dr Sophie Duggan, 50, from Amersham, Buckinghamshire, was driving down a country road in 2013 when their car exhaust came loose - and they booked it in for a repair. 

The medical researcher said her middle son, Freddie, who was six at the time, had been suffering from unexplained swollen lymph nodes, night sweats and weight loss.

'These symptoms were very, very worrying. They had begun when he was around two and they had been getting worse over the years,' Dr Duggan told the Daily Mail. 

'We had reached the stage where we were properly investigating it medically.

'The GP had told us, this is lymphoma until proven otherwise, which was extremely frightening.

'Freddie went to have his lymph nodes scanned and the results came back as non-cancerous but it was still a mystery as to what was going on medically.'

And rather than the doctors being able to explain what was going on, Dr Duggan said it was a mechanic at a garage who discovered the family had been breathing in deadly carbon monoxide from a faulty exhaust pipe.

At high levels, the colourless and odourless gas can cause physical symptoms and be fatal within hours. 

Carbon monoxide is particularly dangerous for pregnant women and can affect baby development as it attaches to cells, limiting the amount of blood carried around the body. 

Dr Duggan said: 'When we came to pick the car up, the guy at the garage asked us if any members of the family had been experiencing unexplained medical problems over the past few years. 

'This was an odd thing for a mechanic to ask and I said "yes". He then said "well I've got your diagnosis out in the yard".

'He showed us what was left of what had been the car's exhaust system. 

'It was completely clogged with wet, sticky black soot on the inside. It had rusted away in places.' 

'Then we got rid of the car and perhaps by coincidence, or perhaps not, Freddie's symptoms went away. This was astonishing. 

'But it was still incredibly worrying to think that we'd been breathing in exhaust fumes, unaware, for goodness knows how many years.' 

Dr Duggan discovered there was a data gap in the UK with regard to the carbon monoxide levels found in cars. 

She was awarded a grant by the Carbon Monoxide Research Trust to go away and measure what people were breathing in in their vehicles. 

'The mechanic who found the fault with the exhaust in our car, said it was something that he saw all the time, week in, week out, in lots of vehicles,' Dr Duggan said. 

'I studied 33 cars and I found some really, really frightening numbers. So 60 per cent of the cars had some carbon monoxide, and a few of those were really, really bad.

'The worst car I tested was a BMW Z4. It was 13 years old, it was a petrol engine and its average carbon monoxide level was 192 parts per million. 

'And the peak levels, whenever the driver engaged the throttle, they actually exceeded the recording range of the data logger I was using.

'That's how bad that particular car was. 

Dr Duggan's story is the latest in a number of instances where people have almost lost their lives to carbon monoxide poisoning in cars. 

Earlier this month, Lucy Barnard, 26 - a pregnant mother - spoke about how she was nearly killed by a pothole after it damaged her exhaust and filled her car with deadly fumes.

She had been driving back to her house on Walney Island in Cumbria, when she suddenly heard a rattling sound after her Ford Fiesta hit a pothole.

Moments later, the carbon monoxide detector she had fitted in her car began to rise to deadly levels. 

Ms Barnard was particularly aware of the dangers of carbon monoxide after her 36-year-old brother Michael died when his car filled up with the gas in August 2023.

Dr Duggan said: 'I have a great foreboding about this. It's that nothing is going to be done until a child dies, and I think it's unavoidable that a child will die.

'In part because children are more vulnerable, but also because petrol and diesel cars, there won't be any new ones on the road from, what four years from now?

'People will be driving older and older petrol or diesel cars. 

'And my study did show a statistically significant correlation between the age of the car and likelihood of the drivers and passengers breathing carbon monoxide.

'Freddie is fit and well now. He's 18. But it was very, very frightening. And, of course, every time he gets poorly, as people do, there's always the worry.

'We wonder could this have been a precancerous thing that's liable to come back? One can't know.' 

Dr Duggan called on proper equipment to be available that people could use to test the carbon monoxide levels in their cars. 

She said: 'If I had a magic wand, one of them would be for people to be able to go out and buy something reliable, that maybe could talk to their mobile phone, something easy to use that could tell them what they're breathing in their cars.

'Another thing would be for the MOT to include an in-cabin air quality test. 

'And the third thing I'd like to see change is when you go to your doctor with symptoms that are suggestive of CO poisoning, and the clinical presentation of that is much wider than you'd think, is that doctors could send you home with a monitor that could test what you're breathing.'