i never used the block but was thinking of puttin one near my exhaust. I had a pot of the gel and it works really well, but in order for it to really work, i had to takee it out of the grow room, remove the lid completely and put an oscilating fan by it so it got a breeze over it ever 10 seconds. works very well. i got lowryders and sour diesel haze autos and pineapple express autos in week 6 flower and my g/f still doesnt know i got them in my closet. she might b able to smell a wiff of ganj now n then but nothin to raise much suspicion. u need a breeze on the ona for it to work. and if its in the grow room it doesnt work it just smells like warm lemony musky skunk pouring out of the closet and stinks the whole house. i cant have a carbon filter coz they r nouisy as hell n i live in a shared house so got no other option but so far so good.
as far as the binding to organic compounds in the air goes, id love to know what that does to my lungs :/ i see on the label it says its designed to be non toxic and thats why i got it, because those plug in air freshners or any other chemical air freshner for houses all say 'may produce an allergic reaction' and 'dangerous to the environment' on the back. so for now i got my confidence in the ona gel
if i start coughing blood or wake up with nosebleeds ill re post