Asthma inhalers, available over the counter from pharmacies will become prescription-only from 2012.

The move comes as worries over ozone layer damage persist from continued use of chlourofluorocarbons to propel the medicine out of the inhaler.

Primatene Mist, the only inhaler still available from pharmacies without prescription is an epinephrine inhaler that causes airways to relax, helping asthma patients during hard times or breathing difficulty. It is not a preventing medicine, but acutely used when airways constrict.

CFC’s (chlorofluorocarbons) are concerning environmentalists, due to their dangerous depletion of ozone, the layer around the earth protecting us from the sun’s harmful rays.

Currently, there are three inhalers on the market, but government officials have decided that OTC’s are to be removed first – restrictions over prescribed inhalers are due 2013. Primatene, made by Amphastar is currently undergoing a propellant redesign, although it is thought that the new inhaler will not be available before the old is phased out, according to the Wall Street Journal.

There are three million users of Primatene reported in 2006, and the FDA says around one to two million are still in use – though it is hard to say how many are over-the-counter (OTC).

"The clock is ticking on Primatene Mist, the only over-the-counter asthma inhaler," FDA press officer Karen Riley said at a news conference.

More than 235 million people worldwide suffer from asthma and it is the most common chronic disease among children, according to the World Health Organization.