Smoke nades?

Can you use smoke nades at the field. I was looking online and i found these smoke nades that have a cool burning and a pull pin activation and I was wondering, are you allowed to use them at the field?

The website is http://sportsmoke.com/

As a rule we do not allow smoke on the field.
However there are times after a good rain (and if you get permission prior to there use) you can you them.
We will some times use them during scenarios (refs will set them off in metal buckets for effect)

They can be a great help when you need to get a push moving.
I'm hoping to find better effects for the field now that the fireworks ban has been lifted!!