Electrets to measure ion concentration in air

Area of Science:

• Environmental Science
• Physics
• Radiation Science

Background:

• Air ions are primarily generated by radon and terrestrial/cosmic radiation.
• Measuring ion concentration offers an indirect assessment of these radiation sources.
• Electrets, charged Teflon, can be used to detect ion concentration changes.

Purpose of the Study:

• To develop and validate a method for correlating electret discharge rate to air ion concentration.
• To establish electrets as a passive, integrating device for measuring ion concentrations.
• To compare electret measurements with a calibrated ion density meter.

Main Methods:

• Environmental electrets were exposed to collect ions.
• The rate of electret charge decrease was measured.
• This discharge rate was correlated with ion concentration data from a calibrated ion density meter.

Main Results:

• A correlation was established between electret discharge rate and ion concentration.
• Ambient air ion concentration was found to be approximately 200 ions/mL, with similar positive and negative ion levels.
• A typical room showed a negative ion concentration of 3,500 ions/mL and no detectable positive ions.

Conclusions:

• Electret discharge rate provides a reliable method for measuring air ion concentration.
• This technique allows for the passive, long-term measurement of both low and high ion concentrations.
• Electrets offer a unique capability for monitoring radiation-influenced environments.