Metered-dose inhalers (MDIs) are devices that people with asthma and chronic obstructive pulmonary disease (chronic bronchitis and emphysema) use to deliver medicine to their lungs. The medication is delivered by a propellant in the MDI. Originally, the propellants were one or more gases called chlorofluorocarbons (CFCs).
CFCs have been replaced in asthma medications, initially with HFA, an environmentally-friendly propellant, or with new delivery systems that do not need a propellant at all. Most inhalers will either be marked with the letters HFA, or will state that they contain no CFCs. Your doctor may need to specify HFA on the prescription to get the appropriate MDI.
Why did CFC MDIs change?
Although CFCs in medicines are safe for patients to inhale, CFCs are harmful to the environment. Scientists have found that when CFCs get into the upper regions of the earth's atmosphere, they reduce the amount of ozone that surrounds the earth. The ozone layer acts as a shield to protect the earth against the sun's harmful rays. With less ozone, too many of these harmful rays reach the earth and can increase the risk of potentially serious health problems, such as skin cancer and cataracts, as well as other health and environmental problems.
To lower the risk of health and environmental problems caused by ozone depletion and to help restore the ozone layer, most countries have agreed to stop using CFCs. The agreement was made in 1987 and is known as the Montreal Protocol.
CFCs were used in many types of products (such as air conditioners and refrigerators), not just MDIs. In response to the Montreal Protocol, the manufacture of CFCs for these purposes has already been stopped. CFC MDIs were given a special exemption because they are so important for treating asthma and chronic obstructive pulmonary disease.
Created by the National Heart, Lung, and Blood Institute. Modified by A.D.A.M., Inc.