While cooking it's very risky to wear polyester garments. If accidentally the garment catches fire the results can be a disaster. Polyester being a synthetic fiber melts when exposed to higher heat. So, in case your dress catches fire, the material will melt and stick to the skin, which is quite difficult to remove. This will increase the harm done. Also polyester is more inflammable than natural fibers.
It is preferable to use cotton clothes in kitchen.