Cool-mist humidifiers

Many Canadians use portable cool-mist humidifiers to increase moisture levels in the air inside their homes. When used as directed by the manufacturer, these products are safe. But using one without properly cleaning and disinfecting it on a regular basis could lead to breathing problems if you have asthma, severe allergies, or other respiratory difficulties.

Types of portable humidifiers

There are three types of portable humidifiers:

  1. Vaporizers - These have a heating element that boils water. They put moisture into the air by sending out a stream of hot mist.
  2. Ultrasonic humidifiers - These produce a micro-fine mist when water is passed over an ultrasonic nebuliser (high frequency vibrating apparatus).
  3. Cool-mist humidifiers - These work without heating the water. A motor forces the water droplets into a mist, which is then dispersed into the air.

Potential health risks of portable humidifiers

Portable humidifiers are not likely to cause health problems if you follow the manufacturer's directions. This usually means:

  • emptying left over water after each use
  • cleaning and disinfecting the water reservoir on a regular basis

With cool-mist humidifiers, there is a risk of health effects if water is left sitting from one use to the next because:

  • Bacteria can collect and multiply in sitting water.
  • A cool-mist humidifier does not boil the water, so it does not kill the bacteria.
  • Re-starting the cool-mist humidifier could send spores or bacteria into the air in your home.

These bacteria or spores could then make matters worse for people who already have problems breathing.

Other concerns

Many consumers have concerns after using cool-mist humidifiers because they notice tiny dust-like particles on furniture nearby. Some models may release high concentrations of the particles into the air when they are filled with tap water.

These particles are made of the same materials that cause the build-up of scale inside kettles, and are considered harmless to most people. But if the tap water used in the cool-mist humidifier contains toxic substances, there is a risk that the particles could be harmful. The number of particles released into the air is generally much lower when using distilled water. However, tap water is fine in most cases, as long as you change the water and clean your humidifier on a regular basis.

Reduce your risk

These steps will help reduce your risk when using a cool-mist humidifier:

  • Clean and disinfect the water reservoir of your humidifier on a regular basis. Follow the manufacturer's directions. Instructions may vary depending on the type of humidifier and how often you use it.
  • Never leave water sitting in a cool-mist humidifier when you are not using it. Always empty the water reservoir when you turn off the humidifier. Clean and refill only when you are going to use it again.
  • Keep the humidifier in a central location and out of your bedroom, especially during the night.

Measure your indoor humidity level with a hygrometer and keep the humidity at around 50% in the summer and 30% in the winter to prevent mould growth. If necessary, you can use a dehumidifier to reduce the relative humidity.

The Government of Canada's role

Health Canada helps protect Canadians from health risks and safety hazards associated with consumer products like humidifiers. As part of this work, we may:

  • support the development of safety standards and guidelines
  • enforce legislation by conducting investigations, inspections, issuing orders, seizures and prosecutions
  • do tests and research on consumer products
  • encourage the design of safer products by giving hazard and technical information to importers, manufacturers and distributors
  • issue product advisories, warnings and recalls
  • promote safe and responsible use of products
  • put regulations in place, when necessary
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