Environmental health issues

A neighbour of ours has a particularly low chimney/exhaust pipe coming out of their ground floor kitchen which deposits smoke and vapour right into our backyard, making it impossible to have the windows in the rear of the house open. We think the outlet legally needs to be a lot taller than it is. We intend to talk to the neighbour about this first but if need be, does anyone have any idea whether there's an environmental health department we could contact in Brussels or in our commune if Schaarbeek?