No Heat

Fan Diffusers

Despite using a fan, these types of diffusers are passive. Fan diffusers work by evaporation of essential oil, and the fan helps to blow the evaporated oil into the air. Of course, blowing a fan across a pad of essential oil will hasten evaporation.
Advantages

  • Less expensive
  • No heat applied so the essential oils properties are not altered

Disadvantages

  • Oil may disperse unevenly (certain components of the oil may evaporate quicker than others)
  • Usually uses a pad to hold the oils, which will need replacement from time to time

Other Passive Diffusers (No Heat)

There are several other methods of passive diffusion, all of which work through evaporation.

Clay, terracotta, or sandstone diffusers
Pendants
Personal inhalers
Room sprays

Advantages:

  • No heat applied, so the essential oil’s properties are not altered
  • Inexpensive
  • Many are portable, so you can take them wherever you go
  • Personal inhalers can be purchased blank, or you can buy them pre-made with essential oil blends

Disadvantages:

  • Essential oils may evaporate unevenly (certain components of the oil may evaporate quicker than others
  • Scent will fade with time, meaning the effects will be strongest at first and then trickle off
  • Some may require replacement pads (pendants, personal inhalers)
  • Clay, terracotta or sandstone may require one scent to fade before a new one is applied

Passive Diffusers-Heat

Candle diffusers

Candle diffusers, sometimes referred to as oil lamps, have a bowl for oils and a space for a candle below the bowl. The heat from the candle warms the oils, speedingĀ evaporation. To use a candle diffuser, a little water is placed in the oil bowl and a few drops of essential oil are added to the water. An electric warmer using similar principles is the Aromastone.
Advantages:

  • Many designs available to suit any decor
  • Inexpensive
  • A natural method to scent a room
  • Can accommodate the use of thicker oils

Disadvantages:

  • Heat may alter the properties of essential oils, possible affecting the therapeutic benefits
  • The components of the essential oils may evaporate at different rates
  • Burning candles must never be left unattended, and should be kept from the reach of children.

Other passive diffusers using heat:
USB diffuser
Car diffuser
Plug in diffuser
Advantages:

  • Quiet
  • Some designs are portable
  • Relatively inexpensive

Disadvantages:

  • Heat may alter some of the properties of the oils, and may alter the therapeutic benefits
  • Requires a power source
  • The components of the essential oils may evaporate at different rates