Troubles arising from cooking in open places

We live in a co-operative society and the boundary of our society is connected to the common plot of another society. There is a separation wall in between. On the side neighboring society uses the common plot for public gathering on frequent basis and they prepare food for the guests in open. Due to this very foul smell arises on daily basis which creates trouble to our people. I am not sure how they are allowed to create such nuisance to other citizen and how a place not registered for cooking is being used for it? We want to take legal actions against them but are not aware about the laws. Please help.