I read that the air purifiers that can create negative ions also increase ionization, in theory is it possible to create a negative charge/ negative ions without creation ionization similar to waterfalls, etc.?

  • 6
    $\begingroup$ I'm unclear on what you really mean. If you are making negative ions, you are ionizing them. $\endgroup$
    – Jon Custer
    Sep 22, 2020 at 23:23
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    $\begingroup$ Waterfalls? What do you mean? $\endgroup$ Sep 23, 2020 at 6:50
  • $\begingroup$ Waterfalls create negative ions, I was wondering if by doing so do they create ozone as well? $\endgroup$ Sep 24, 2020 at 15:28

2 Answers 2


An air ioniser (or negative ion generator or Chizhevsky's chandelier) is a device that uses high voltage to ionise (electrically charge) air molecules. Negative ions, or anions, are particles with one or more extra electrons, conferring a net negative charge to the particle. Cations are positive ions missing one or more electrons, resulting in a net positive charge. Some commercial air purifiers are designed to generate negative ions.

Matter consists of neutral atoms and molecules, there are as many electrons ( negative particles) as positive ( protons) in the universe is axiomatic because that is what has been observed, conservation of charge is inherent.

The way the air purifiers work is by separating the electron from the atoms/molecules and allowing it to attach (by the laws of quantum mechanics) to neutral atoms/molecules making negative ions. This means that the parent of the electron becomes positive, and in the single processor described above it is inevitable that there will also be positive ions.

One could create a beam of electrons of appropriate energy and negatively ionize the air. The charge balance would happen where the beam of electrons was formed, leaving positive ions in the region of generation. In total space, charge would add up to zero, but there can be a separation of charges.


If you are asking : "Can we create negative ions without creating positive ones?"

The answer is: No.

Whenever a neutral system is provoked to generate ions then equal amount of oppositely charged ions are created (always). This is simply the law of conservation of charge.

  • $\begingroup$ Technically, you could produce free electrons or positrons. Those don't count as ions. $\endgroup$ Sep 23, 2020 at 6:25
  • $\begingroup$ @JohnDvorak Initially I used the word positive or negative charge but then I considered that the OP is specifically asking for ions and hence I reworded the answer. $\endgroup$
    – user249968
    Sep 23, 2020 at 6:28
  • $\begingroup$ But if it still bugs the reader then they can simply swap "ions" with "charge" in their mind and get the more general answer. $\endgroup$
    – user249968
    Sep 23, 2020 at 6:31
  • $\begingroup$ I would be interested in learning how to produce free electrons as well if you don't mind explaining it to me, thank you! $\endgroup$ Sep 24, 2020 at 15:27
  • $\begingroup$ @user6759997 I have even better idea. Why don't you come to h-bar. You can talk to more knowledgeable users like John Rennie. $\endgroup$
    – user249968
    Sep 24, 2020 at 15:34

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