Cleaner air & microbes

Ions and the air we breathe.

In the laboratory, ions can clear particles from the air and reduce the viability of airborne bacteria. Here is what has been tested, and the important caveat from the ozone question.

~95% / ~70%

drop in viability of S. aureus and E. coli after 12 hours of ion exposure in a 2021 laboratory study (Comini et al.).

10–12 minutes

for the strongest ionizer to clear particles from a small test chamber (Grinshpun et al., 2005).

3 hours

was enough to reduce the viability of bacteria trapped in filters in the same 2021 study.

The studies

  1. Encouraging

    Evaluation of ionic air purifiers for reducing aerosol exposure in confined indoor spaces

    Grinshpun SA, et al. · Indoor Air 15(4):235–45 · 2005

    Chamber experiment, 5 devices

    The strongest unit cleared particles from a small chamber within about 10–12 minutes. Particles are deposited on surfaces, not destroyed.

  2. Background

    Negative air ions and their effects on human health and air quality improvement

    Jiang S-Y, Ma A, Ramachandran S · International Journal of Molecular Sciences 19(10):2966 · 2018

    Narrative review

    Negative ions can remove particulate matter, but there is no consistent, reliable evidence of therapeutic effects and antimicrobial claims are contested. Parts read as promotional.

  3. Early

    Positive and negative ions potently inhibit the viability of airborne Gram-positive and Gram-negative bacteria

    Comini S, et al. · Microbiology Spectrum 9(3):e00651-21 · 2021

    Laboratory study (S. aureus and E. coli on plates and trapped in filters)

    Ion exposure reduced bacterial viability in every condition tested: about 95% for S. aureus and 70% for E. coli after 12 hours on plates, and effects within 3 hours on bacteria trapped in filters. These are laboratory results, not infection rates in people.

  4. Listeddetails to confirm

    Bactericidal effects of negative and positive ions generated in nitrogen on starved Pseudomonas veronii

    Noyce JO, Hughes JF · Journal of Electrostatics 57(1):49–58 · 2003

    Laboratory study

    Tested bacterial kill by ions generated in nitrogen, an approach used to look at ion effects without ozone. A summary of its results is still to be added.