Emma Bartholomew hears from a GP who was arrested twice during the Extinction Rebellion protests this month, and how London’s filthy air means even non-smokers now have measurable carbon monxide levels in their airways

"As I sat in the cell, I read signs on the ceiling asking me to stop being a criminal and instead become a good citizen, but in this bizarre situation we find ourselves in, it is possible to be both."

Manor House GP Chris Newman had never been to a protest until he joined Extinction Rebellion campaigners last October, calling for the government to take drastic action on climate change - but a year on he was one of 21 doctors who were arrested as part of the non-violent direct action group's two-week autumn uprising.

As he sat in the middle of the road, obstructing the entrance to City Airport, a police officer asked if there was anything they could do to persuade him to move - but he had already made up his mind he was staying put.

It took two officers to drag him to the pavement, where he waited for two hours before a van arrived to take him off to the cells.

Chris blames the government's reluctance to listen to science for the roundabout tactics that the group has employed - and which have come under fire from some quarters for "wasting police time".

He also wants to let the public know the lengths that some doctors, nurses and healthcare professionals are willing to go to protect them from climate breakdown.

"They need to see that this is serious," he said. "It would be hard for anyone to argue that us taking annual leave to sit for hours on cold streets and risking arrest is something pleasurable. There is no personal gain in this, other than the sense of unity that comes from collective action.

"Science is not partisan. It is not prejudiced and it is not sentimental. If we don't respect the laws of nature, the majority of us will be wiped off the planet. Thankfully more and more people are realising this.

"Unfortunately, our politicians think everything is up for negotiation, but you can't negotiate with a changing climate, with droughts, disease and crop failures."

In terms of the impact on our health, Chris cites climate research which indicates there will be unprecedented deaths from heat waves, severe weather and social unrest caused by mass "climate immigration", as well as water insecurity, malaria spreading north and Lyme disease becoming more prevalent. Since the Paris Accord three years ago, global emissions have increased by 5 per cent, and some recognised scientists put the risk of complete human extinction at 5pc in the next 80 years.

On the ground here in Hackney, healthcare professionals are already seeing the effects that hotter summers are having - like in August when temperatures peaked at 37 degrees.

Specialist respiratory physiotherapist at the Homerton Hospital, Laura Graham, whose patients suffer from the likes of chronic obstructive pulmonary disease and asthma, told the Gazette: "I can anecdotally tell you that in the summer when it is hotter weather we do get more breathlessness reported to us.

"Extreme spikes in temperature exacerbate patient symptoms and our patients get breathless, have chest tightness, wheezing, coughs, and they might have reduced exercise tolerance or fatigue."

On top of contending with global warming, air pollution is a silent killer, and in central London nitrogen dioxide levels are as much as five times over the European legal limit. Air pollution is linked to asthma, heart disease and dementia.

Laura will be running a stand for the smoking cessation campaign Stoptober this week and testing smokers with a carbon monoxide (CO) monitor to test the levels in their blood.

In heavy smokers an element of CO stays within the breath or airways, and the monitor measures the exhaled CO.

But in London - because pollution is so bad - even non-smokers register with CO.

"CO has an effect on the body's ability to carry oxygen," said Laura. "If you have higher CO you have less ability to take up the oxygen.

"A smoker could be from nine to 30 on the scale. But yesterday we had someone who didn't smoke that was five - they had been out by a main road.

"If you were out by the sea or in the countryside you would probably register as zero. There's an element of carbon monoxide we are all inhaling because of the pollution. If you have been out in the street, exercising or waiting near a main road, your level might be slightly raised, so we recommend people take routes that aren't by main roads.

"It's normal to see non smokers register at three or four on that scale, and it does surprise people."