Petition Allergy announcement on aircraft

I would like to make it mandatory for flights leaving or entering the uk to make passengers aware of any severe allergies of passengers who are travelling on the same flight that the passenger discloses to the airline. Specifically nuts as the dust from when they are consumed is the most likely allergen to cause airborne reactions onboard aircraft. Other passengers should be made aware prior to boarding, preferably at check in or even before via email or other communication so other passengers have time to purchase replacement snacks with a reminder onboard. (I speak as the mother of an anaphylactic child who reacts airborne to dairy egg and nut)