There ae a few hazers out there that should do the job for you, an 800W unit would probably be adequate for the size floor you are looking at. If you can fix it a bit below the lights and ideally a bit behind them it will be the best effect. Most hazers blow at about a 45deg angle and once you've got some haze into the room you'll be able to keep it topped up and the effect going by mounting as suggested.
Le Maitre and others publish the COSHH data on their fluids and there are even some out there that are 'good' for asthmatics, we typically only use le Maitre fluid but I suspect most are near as danmit the same but we have to be seen to be taking every possible precaution and I would advise you to do the same. Don't be tempted to get the cheapest, they are not worth it in the long run.
As for scent I would advise strongly against it unless you are sure what they are, Froggy's are OK in our experience, many others are oil based and not only will they be detrimental to your machine they may also be harmful.
A good basic bit of info can be found here http://www.hse.gov.uk/pubns/etis3.pdf