theres very few people over here in belfast growing. Thought last year or the year before there probly would have been none. this is my first grow ive read and read and read till i feel asleep. soo i hope my babies grow with no problems specialy mould that would be the worst. how important is having air extractor or having fresh air coming in other than a few oscilating fans in the room to keep the place cool. my q is how important is fresh air?