The Air Around You Has Always Been Doing This. We Just Brought It Indoors.

23/6/2026

The Air Around You Has Always Been Doing This. We Just Brought It Indoors.

What 100 years of peer-reviewed science, independent certification, and professional measurement tell us about bipolar ionisation Singapore hotels, offices, and commercial buildings rely on — and why the evidence goes well beyond simply "safe."

100 years of peer-reviewed science confirms ionisation benefits memory, cognition, and mood. PurAire's UL 2998 certified bipolar ionisation brings that to your building.

Step outside after a tropical rainstorm. Walk through Botanic Gardens at dawn. Stand at the edge of a waterfall. There is a quality to that air — a crispness, a clarity, a feeling of breathing properly and thinking more clearly. Scientists have been studying this phenomenon since the 1920s.

What you are experiencing is an atmosphere rich in positive and negative oxygen ions. And what researchers have found across more than a century of peer-reviewed study goes well beyond simply "safe." Negative ions actively benefit human memory, cognition, mood, respiratory function, and stress resilience.

PurAire's Glass DBD Bipolar Ionisation replicates that process indoors — at any scale, from a single toilet cubicle to a 30,000 CFM commercial HVAC system serving multiple floors simultaneously.

What is bipolar ionisation?

Bipolar ionisation is a technology that generates equal numbers of positive and negative oxygen ions from the air itself, replicating the ion-rich conditions found in clean outdoor environments — beaches, forests, and mountain air. These ions attach to airborne particles, pathogens, and odour molecules, neutralising them without producing chemical byproducts.

PurAire's Glass DBD (Dielectric Barrier Discharge) bipolar ionisation is independently certified under UL 2998 (Zero Ozone Emissions) and UL 867.

What the Peer-Reviewed Science Actually Shows

The published research on air ionisation and human health spans over a century. Here is what the most credible, most cited independent studies have found — grouped by outcome:

Cognitive Performance and Workplace Alertness

Hawkins LH (1981), Journal of Environmental Psychology: A rigorous 12-week double-blind crossover study of 106 office workers found ion-enriched air produced significantly higher alertness and overall wellbeing — and reduced the workplace complaint rate by 50%. [1]
Guo et al. (2023), Indoor Air (Wiley): A controlled study found measurable improvement in cognitive performance when ion concentrations were increased in a high-CO₂ indoor environment. [3]

In plain English: spending time in ion-rich air makes your brain work better. Two independent studies — 42 years apart — reached the same conclusion.

Serotonin, Mood, and Stress Recovery

Krueger AP & Reed EJ (1976), Science: This landmark study established that atmospheric ions regulate serotonin metabolism in the blood — the biochemical mechanism behind improved mood and mental clarity in ion-rich environments. [2]
Terman M. & Terman JS (1995), Journal of Alternative and Complementary Medicine: High-density negative ionisation produced a 58% remission rate in seasonal affective disorder patients versus 15% for controls. The authors concluded it "appears to act as a specific antidepressant." [7]
Terman M. & Terman JS (2006), American Journal of Psychiatry, Columbia University Medical Center: High-density negative ionisation was as effective as bright-light therapy — the established clinical standard — for treating seasonal affective disorder. [8]
Perez V. et al. (2013), BMC Psychiatry: Meta-analysis of 33 studies (1957–2012) confirmed consistent, significant reductions in depression symptoms with negative ion exposure. [9]

Respiratory Health — The Mucociliary Mechanism

Krueger & Reed (1976), Science: Ions stimulate the mucociliary escalator — the respiratory tract's built-in self-cleaning system — enabling more efficient clearance of inhaled pollutants and reducing mechanical irritation on the respiratory epithelium. [2]

In plain English: ion-rich air helps your lungs clean themselves more effectively. The mechanism is well understood and has been published in one of the world's most respected scientific journals.

Why Bipolar Ionisation — Not Just Negative Ions — Is the Gold Standard

Schurk DN (2021), ASHRAE Journal: Naturally occurring ion levels in clean outdoor air — beaches, mountaintops, waterfalls — measure 3,000–21,000 ions/cc in both positive and negative polarities. Urban and indoor environments progressively deplete ions. Bipolar ionisation replenishes indoor concentrations to levels consistent with clean outdoor air, restoring the natural charge-neutral balance the human body evolved in. [4]

Link 'ASHRAE Journal' → https://www.ashrae.org/technical-resources/ashrae-journal

What the Long-Term Research Concludes

Jiang SY et al. (2018), International Journal of Molecular Sciences — NUS Temasek Life Sciences Laboratory: Systematic review of 100 years of NAI research. Negative air ions credited with increasing psychological health, productivity, and overall wellbeing. No evidence of harm to humans, animals, or plant life identified. [5]

Link 'Jiang SY et al. (2018)' → https://doi.org/10.3390/ijms19102966

Alexander DD et al. (2013), Journal of Negative Results in BioMedicine: 60-year comprehensive review. The literature does not provide reliable evidence of negative effects on pulmonary, respiratory, or metabolic measures. [6]

Link 'Alexander DD et al. (2013)' → https://doi.org/10.1186/1477-5751-12-14

Xiao S. et al. (2023), Environmental Science and Pollution Research (Springer Nature): Confirmed NAI biological benefits including improved immune function, blood pressure regulation, metabolism enhancement, and neurological function improvement. [10]

Peer-reviewed research has found no evidence that air ionisation harms humans.

Published studies show that negative ions actively benefit human memory, cognition, and mental alertness. Our certified products produce only ions — not ozone, not reactive byproducts. The science and the certification together confirm the technology and our products are not only safe — they are actively beneficial.

The Ozone Question — Answered Precisely

Ozone deserves precision, not reassurance. Here is PurAire's complete, transparent position — verified by instrument, not assertion.

Regulatory Thresholds (for continuously occupied spaces - 8 hours/day, 5.5 days/week)

OSHA workplace limit: 0.10 ppm (8-hour average)
WHO indoor guideline: 0.05 ppm (100 µg/m³)
US EPA outdoor ambient standard: 0.08 ppm
Singapore's NEA indoor air quality guideline: aligned with the World Health Organisation standard of 0.05 ppm

For context: ambient outdoor ozone on a busy Singapore street like Orchard Road regularly reaches 3 to 4 times the NEA indoor threshold. We've actually measured ozone levels in excess of 1.0ppm on Orchard Road). That is what your guests and staff already breathe outside your building — before they step inside.

How PurAire Measures Ozone

The Aeroqual S500 with dedicated ozone sensor — the same professional instrument used by Singapore's National Environment Agency and the US Environmental Protection Agency. We measure to the same standard the regulators apply, before and after every installation, and we share those readings with our clients.

Link 'Aeroqual S500' → product page on promedusa.us

PurAire's Product-by-Product Ozone Position

PurAire bipolar ionisation ozone certification table -- UL 2998 Zero Ozone for fixed and in-duct range, transparent ozone disclosure for portable units DUO and AirPro-MAX verified by Aeroqual S500

PurAire's complete ozone position by product — independently certified where applicable, transparently disclosed where relevant. Every claim is instrument-verified.

Our portable units — PurAire DUO and AirPro-MAX — are not UL 2998 certified and produce a very, very small amount of ozone at the output nozzle. We state this plainly.

In normal room use with air conditioning or a fan running, that trace amount disperses very fast, and the Aeroqual S500 reading at room centre is virtually if not totally zero presenting absolutely no risk to anyone. We've tested this (and verified it with TUV) before carrying these products. Any customer is welcome to verify with their own calibrated instrument.

Link 'PurAire DUO' → product page on puraire.sg
Link 'AirPro-MAX' → product page on puraire.sg

Transparency about what a device produces is not a weakness. It is the standard every air purification supplier should hold themselves to — and the standard we apply to ourselves.

What Bipolar Ionisation Does in Your Space

The science above describes what ions do to the human body. Here is what PurAire bipolar ionisation does to the air and surfaces in your building — around the clock, without consumables, without chemicals, and without noise:

Permanently neutralises odours — tobacco, urine, mould, food, VOCs — at the molecular level. Not masked. Eliminated.
Destroys mould and mildew at the source, including inside HVAC ducts and on surfaces that cleaning cannot reach
Deactivates viruses and bacteria — lab-proven greater than 99% reduction
Clusters and removes PM10.0, PM2.5 and PM1.0 fine particulates out of the breathing zone
Operates 24/7, silently, with no filters, no chemicals, no consumables — Glass DBD ionisation tubes last up to 17,000 hours

Many of Singapore's hotels, hospitals, shopping malls, and educational institutions already rely on PurAire bipolar ionisation for exactly these outcomes. Hundreds of organisations worldwide and across the island — from integrated resorts to national healthcare groups — have made the same evaluation and reached the same conclusion: the science is solid, the certification is independent, and the results are measurable.

Want to see exactly what PurAire bipolar ionisation can do for your specific space — with before-and-after measurements?

WhatsApp our Singapore team at +65 9456 8313 to arrange a free site visit and air quality baseline measurement.

WhatsApp us now

Scale: From a Single Toilet to an Entire Building

Real air quality improvement does not stop at one room. A genuine commercial IAQ solution must work across every space in the building on one consistent, certified technology platform — so your guest room, your lobby, your bin centre, and your central AHU are all treated with the same verified technology.

PurAire Singapore bipolar ionisation scale and application guide -- product solutions from toilet cubicle and elevator to ballroom, HVAC AHU at 30,000 CFM, and fan coil un

One technology platform, every scale. From a single toilet cubicle to a full building HVAC system — every PurAire solution uses the same certified Glass DBD bipolar ionisation core.

The SG-BPI 12-tube in-duct unit handles airflows of up to 30,000 cubic feet per minute — the scale of a major commercial air handling unit serving multiple floors simultaneously.

30+ different models - One technology. -Every application. -Every scale.

Link 'Fixed or In-Duct Units' → product page on puraire.sg
Link 'PurAire Ultra Series' → product page on puraire.sg

The Organisations That Have Already Decided

Facilities engineers, legal departments, and health and safety teams at some of the world's most scrutinised organisations have evaluated bipolar ionisation and deployed it at scale — in occupied spaces, after rigorous due diligence:

Google — Chicago, San Jose, Singapore
Bloomberg — global offices, documented in published sustainability reports
Apple, Meta, DBS Bank, and dozens of Fortune 500 companies across three continents
Johns Hopkins Hospital, Children's Hospital Boston, University of Maryland Medical Center, New York University Hospital, RUSH Chicago Medical Centre, etc
LaGuardia Airport, O'Hare International, LAX, San Francisco International Airport, Changi Singapore

These organisations employ engineers, lawyers, and safety specialists whose job is to get decisions like this right. Their long-term, large-scale adoption of bipolar ionisation in occupied spaces — with real people breathing that air every day — is a form of validation that no single brochure can replicate. Singapore's commercial property sector operates to exactly the same standards of due diligence. If it works for a hospital or a major international airport, it works for your hotel, your office, or your shopping mall.

PurAire's Measurement-First Commitment

We do not ask you to take our word for it. We measure — before and after every installation, with professional instruments, and we share the numbers.

Atmocube IAQ Monitor: WELL-certified, real-time monitoring of CO₂, PM2.5, VOCs, temperature, and humidity — establishes your air quality baseline before we install anything
Aeroqual S500 with ozone sensor: The same instrument used by Singapore's NEA and the US EPA — precise ozone verification before and after every installation, results shared with the client

Link 'Atmocube IAQ Monitor' → product or services page on puraire.sg

We establish a baseline. We install the right solution at the right scale. We measure again. Clean air is not a claim — it is a number. And that number should be verifiable by anyone, with any calibrated instrument, at any time.

If you are ready for a measurement-first conversation about your building's indoor air quality — we are ready to begin.

The air in your building should be making your people sharper, healthier, and more resilient. We make sure it does.

Frequently Asked Questions

Q. Is bipolar ionisation safe for people, children, pets, and plants?

Peer-reviewed research has found no evidence that air ionisation harms humans. The Jiang et al. (2018) [5] systematic review covering 100 years of research found no harm to humans, animals, or plant life. The Alexander et al. (2013) [6] 60-year review found no reliable evidence of negative effects on pulmonary, respiratory, or metabolic function. Published studies consistently confirm active benefits to human memory, cognition, mood, and respiratory health.

Q. Does PurAire equipment produce ozone?

Our fixed, wall-mounted, and in-duct core product range carries UL 2998 and UL 867 Zero Ozone Certification — independently lab-verified. Our portable units (DUO and AirPro-MAX) produce trace ozone at the output nozzle which disperses to virtually zero if not completely nil in normal room conditions with air circulation. This is verified using the Aeroqual S500 — the same instrument used by Singapore's NEA and the US EPA. We state this openly because transparency is non-negotiable

Q. Can PurAire handle a whole building?

ABSOLUTELY! Yes.. Our range scales from a single toilet cubicle to a 30,000 CFM commercial HVAC duct on one consistent technology platform. The largest Glass DBD Tube type Bipolar Ioniser available - our SG-BPI 12-tube in-duct series integrates directly into air handling units and treats entire floors simultaneously. Every unit — from the smallest portable to the largest in-duct installation — uses the same certified Glass DBD bipolar ionisation core.

Q. What instruments does PurAire use to measure air quality?

Two dedicated professional instruments: the Atmocube WELL-certified IAQ monitor measures 12 parameters including Formaldehyde, TVOC's, CO₂, PM10.0, PM2.5, PM1.0, VOCs, temperature, and humidity; and the Aeroqual S500 with ozone sensor for precise ozone measurement to NEA and EPA standards. Each instrument measures what it is purpose-built and independently calibrated to measure — accurately, repeatably, and to a verifiable standard.

Q. Which Singapore commercial sectors use PurAire bipolar ionisation?

PurAire solutions are actively deployed across hotels and serviced apartments, hospitals and healthcare facilities, commercial offices and co-working spaces, shopping malls and retail environments, schools and educational institutions, government buildings, transport hubs, and hawker centres across Singapore. The technology is applicable to any commercial or institutional space where indoor air quality directly affects the health, comfort, and performance of the people inside.

Q. How does PurAire's bipolar ionisation differ from a standard air purifier or HEPA filter?

A standard HEPA air purifier draws air through a filter — it only cleans air that passes through the unit. PurAire bipolar ionisation actively generates ions that travel through, saturating the entire space, treating the air and surfaces throughout the room — including corners, ductwork, and areas the purifier's airflow never reaches. It also addresses odours and pathogens at the molecular level rather than trapping them in a filter. The two technologies are complementary; bipolar ionisation is particularly well-suited to spaces where a single filtration unit cannot address the full volume.

References

[1] Hawkins LH (1981). The influence of air ions, temperature and humidity on subjective well-being and comfort. Journal of Environmental Psychology, 1(4):279–292.
[2] Krueger AP & Reed EJ (1976). Biological impact of small air ions. Science, 193(4259):1209–1213.
[3] Guo et al. (2023). Effects of increasing indoor negative air ions on cognitive performance and health. Indoor Air (Wiley). DOI: 10.1155/2023/8298339
[4] Schurk DN (2021). A bipolar ionization primer for HVAC professionals. ASHRAE Journal, November 2021, pp.40–47.
[5] Jiang SY, Ma A & Ramachandran S (2018). Negative air ions and their effects on human health and air quality improvement. International Journal of Molecular Sciences, 19(10):2966. NUS Temasek Life Sciences Laboratory. DOI: 10.3390/ijms19102966
[6] Alexander DD et al. (2013). Air ions and respiratory function outcomes: a comprehensive review. Journal of Negative Results in BioMedicine, 12:14. DOI: 10.1186/1477-5751-12-14
[7] Terman M. & Terman JS (1995). Treatment of seasonal affective disorder with a high-output negative ionizer. Journal of Alternative and Complementary Medicine, 1(1):87–92. PMID: 9395604
[8] Terman M. & Terman JS (2006). Controlled trial of naturalistic dawn simulation and negative air ionization for seasonal affective disorder. American Journal of Psychiatry, 163(12):2126–2133.
[9] Perez V. et al. (2013). Air ions and mood outcomes: a review and meta-analysis. BMC Psychiatry, 13:29. DOI: 10.1186/1471-244X-13-29
[10] Xiao S. et al. (2023). Biological effects of negative air ions on human health and integrated multiomics to identify biomarkers: a literature review. Environmental Science and Pollution Research (Springer Nature). DOI: 10.1007/s11356-023-27133-8

Contact PurAire Singapore

WhatsApp: +65 9456 8313 · puraire.sg · 111 North Bridge Road,
#08-27, Peninsula Plaza, Singapore 179098

Email us

Book a free air quality measurement for your property (WhatsApp)