The right canister is any of them, most of the isotopes will be bound to dust, and anything you can do to reduce the dust you breathe in helps. Gaseous isotopes

The right canister is any of them, most of the isotopes will be bound to dust, and anything you can do to reduce the dust you breathe in helps. Gaseous isotopes like iodine aren't that easy to filter, you are better off taking iodine tablets for that.