Pass air over, or bubble it through, cold water to add water molecules to it. This is called evaporation and the invisible water is humidity. Steam, produced by heat, makes a cloud of tiny water drops which only become humidity when they evaporate as the steam disappears. Both systems produce humidity, but steam does it faster and can vaporize aromatic oils to relieve nasal congestion and help mobilize thick mucus, according to Mayo Clinic pediatricians.
Benefits
Scientists at the U.S. Environmental Protection Agency, or EPA, say cold and steam humidifiers offer different benefits. Use a cold humidifier, usually a room temperature unit, to humidify slowly, keep air comfortable and prevent drying of airways. Use steam to quickly saturate your room air. This helps to quickly reverse drying that has already occurred. Sometimes the term "cold humidifier" refers to a mist generator using ice or refrigeration to saturate an enclosure, a mist tent, to treat serious pediatric respiratory conditions often accompanied by fever.
Dangers
EPA scientists warn that cold water room humidifiers usually contain a refillable reservoir. By continually evaporating water, any contaminants, minerals or bacteria will build up over time. An unsanitary pool of dirty water can develop rapidly. Mayo Clinic physicians advise you to change the water and clean the reservoir at least daily.
A steam humidifier heats water to boiling, which kills bacteria. Keep a hot steam humidifier out of your child's reach and fastened it securely. The hot steam and heating elements could be dangerous. Contaminants and water minerals are concentrated as water boils away into steam, creating scale on heating elements and possibly clogging the system. This can require frequent cleaning. A steam humidifier, if it boils dry, is a fire hazard.
Delivery
Clinical practice guidelines published in 2002 by the American Association for Respiratory Care indicate that humidity should be added to a dry, therapeutic gas like oxygen, which is supplied chemically pure and totally dry. If you suffer from chronic obstructive pulmonary disease, or certain heart conditions, you may need oxygen. The gas is bubbled through cold water to humidify it and save your nasal passages from excessive and uncomfortable drying. This humidified gas is breathed through a cannula, a tube strapped under your nose.
Never deliver the output of a steam humidifier directly into your nose or face. Direct the steam into the room to humidify the air you breathe but keep it at a sufficient distance to prevent burns.
Additives
Dr. Jay Hoecker, with the Department of Pediatric and Adolescent Medicine at the Mayo Clinic, says you can add camphor, eucalyptus or menthol to steam humidifiers as a traditional aid to breathing and to relieve a hacking cough and nasal congestion. Many children and adults find such home remedies soothing. Physicians often advise using these additives with steam humidifiers, but check first to be sure it is appropriate for your condition. Do not add these aromatic substances to cold humidifiers. They do not vaporize sufficiently from cold water to provide therapeutic effects in the air.
Devices
Well made and tested medical devices are available for steam or cold humidification. Misuse can have serious consequences. EPA scientists warn against nebulizers, which spray whole, cold water droplets into the air, making them different from humidifiers. Contaminants or bacteria are spread with the water. Your physician can prescribe safe products and suppliers. An appropriate prescription also helps you get the best insurance coverage.
