A creative pupil from Cardiff has been crowned the winner of a national competition, after designing a striking poster warning of the dangers of carbon monoxide (CO) poisoning. Naomi Rahman, who is 11 years old created her poster to demonstrate the silent and deadly effects of carbon monoxide – an odourless, colourless gas which kills around 36 people each year and injures more than 250 people. The national schools’ poster competition is run by independent registered charity, CO-Gas Safety, which…