Re-upholster an old chair with a T-shirt

Step 3 Bag it

Put the whole cushion in a plastic bag. This will trap all the dust, mold and years of funk that have built up in your crusty old cushion.

People will allergies will thank you.

(By the way, if you have dust allergies, you should get rid of your carpet NOW. You should get rid of your carpet anyway because it's made of toxic chemicals that off-gas for the whole lifespan of the carpet.)