Recently my neighbour downstairs has been renovating their flat and put up a new vent for their boiler. You may see the picture here:
I have contacted my neighbour about the problem but he is unwilling to accept it is a problem.
I then contacted Environmental Health of Camden council and they are unwilling to assist, saying that this is a private dispute between two owners of the property (I own the upstairs flat, they own the downstairs flat). This is despite me telling them that life may be at risk due to the carbon monoxide from the fumes.
I do not know who else to contact and desperately need some advice.