Disclosure, my family had open fires and then log burners for as long as I've been alive. Not in London where I now live. I love a proper fire, it's great, one of the things I enjoy about visiting family in the countryside.
I am, however, ambivalent about the things and wouldn't resent them being banned.
[0] https://www.theguardian.com/environment/2022/mar/30/home-woo...
Not in the context of London, but I live near an amusement park and they launch fireworks every weekend while the park is in season. I don't smell or notice any difference in air quality except for after the 4th of July when they launch a lot more of them.
_Disclosure I also have open fire pit in a garden, and love occasional fire_
I will say that if folks are having proper bonfires - that absolutely makes a difference. Largely because they are not burning dry wood.
I live in the middle of a city centre. My next door neighbour burns coal in an open fire too, it's shocking.
I don't disagree with you, but when I'm looking at saving £250/month on top of all my other costs skyrocketing, it becomes an attractive thing to use.
Generally the stoves are designed specially for this. The stove burns hotter and may have a second combustion chamber. DIYers welding in the catalytic converter from a car is not the norm and not expected to be safe, but I bet there are some hackers who have made it work.
[0] https://ambassadorfireplaces.com/the-difference-between-cata...