4 hi grade plants how can i hide the smell

im going to grow 4 highgrade plants in my loft conversion compartments and im not sure if the smell will come out any ideas??

get a carbon filter and a fan to filter out the smell.

like these:
http://www.google.com/products?q=carbon can fan&oe=utf-8&rls=com.ubuntu:en-US:official&client=firefox-a&um=1&ie=UTF-8&sa=N&hl=en&tab=wf

thanks for help might look into ozone generators too