Note to the easily alarmed: "Chemical-free" does not mean what you think it means.
The term has quite irritatingly become shorthand for "scary compounds we know nothing about and thus must be bad," used to describe whatever a company wants you to think is gentle, benign or guaranteed safe. Enough, I say! As a description of tangible substances, it's wrong. And I want you not to be fooled by it.
Here's an about.com answer to the question What is a chemical?
"Short answer: Everything is a chemical. Longer answer: Chemistry is the study of matter and its interactions with other matter. Anything made of matter is therefore a chemical. Any liquid, solid, gas. Any pure substance; any mixture. Water is a chemical. Technically speaking, so is a chunk of your computer."
Oxygen? A chemical element. Water? A combination of the chemical elements hydrogen and oxygen. The human body? A whole passel of chemicals -- naturally occurring ones, no less.
There's more, but that's probably enough for today. If not, here's a fun site, chem4kids.com. Don't be chastened by the name. The very friendly home page does state that "it's for everyone."
As for the "kill swine flu without use of chemicals" reference, it's from a pitch for a product that uses tap water.
-- Tami Dennis