The Dutchman Hendrik Zwaardemaker (1857 – 1930) discovered in 1900 that two different scents can neutralize each other. These neutralizing capacity applies only to specific pairs (called Z-pairs or Zwaardemaker pairs).
The exact reason for this neutralizing effect is never fully understood, but there is at least no chemical interaction involved in this process. There are optimal concentrations of the 'counter-smell' depending on the type and concentration of the pollutant.
Examples of Z-pairs:
• Butyric acid < — > Juniper
• Chlorine < — > Vanilla
• Ammonia < — > Violets
• Tobacco < — > Wintergreen
