Reactive Oxygen and Nitrogen Species (RONS)

Reactive oxygen and nitrogen species (RONS) is the collective term for short-lived, chemically reactive molecules and ions containing oxygen and/or nitrogen. In the context of this wiki they are the proposed active agents in Plasma-Activated Water (PAW), produced when a Non-Thermal Plasma (Cold Atmospheric Plasma) discharge contacts water.

Members commonly cited

• Hydrogen peroxide — a relatively long-lived oxidising species among the group.
• Nitrite and nitrate — nitrogen oxides that dissolve into water and contribute to the pH shift of plasma-activated water.
• Peroxynitrite-related species — highly reactive intermediates formed from the interaction of oxygen- and nitrogen-derived species.

Why they matter

RONS are the reason plasma-activated water differs chemically from untreated water: they raise the oxidation–reduction potential and, through the acids formed from nitrogen oxides, lower the pH. Their short lifetimes mean the properties of treated water decay over time.

Evidence status

This page describes the chemistry as generally understood. It does not report measured concentrations, dosages, or effects from the source dossier, whose ingested capture is incomplete and contains no such data.

Short-lived and long-lived species

Not every member of the group is fleeting. A 2026 paper on antimicrobial testing distinguishes short-lived species such as hydroxyl radicals from long-lived ones such as ozone and hydrogen peroxide, and reports that in its treated hard water ozone fell by 56% and hydrogen peroxide by 28% over 24 h at 4°C, with larger losses when bacteria were present, while nitrite and nitrate stayed nearly constant. Its measurements and their limits are set out in The Neutralization Problem: Why Plasma-Activated Water Kill Rates May Be Overstated.

Measured concentrations in tap water

A 2018 paper tracking tap water through 30 minutes of dielectric barrier discharge treatment reports hydrogen peroxide reaching 1.85 ± 0.16 mmol/L, nitrate 3.55 ± 0.42 mmol/L, and nitrite peaking at 175.36 ± 9.67 µmol/L after 10 minutes before declining, which the authors attribute to ozone converting nitrite to nitrate inside their sealed enclosure. The full set of figures and its limits are in What Plasma Does to Tap Water: Sixteen Measured Species, a Conductivity Check and a Lentil Trial (Judée et al., 2018).

Discharge type changes the mix

A 2025 study comparing two air discharges over water reports that a spark discharge gave 1.357 mM hydrogen peroxide plus nitrate, while a glow discharge gave mainly nitrate and nitrite with negligible peroxide; in scavenger tests, removing peroxide or singlet oxygen abolished killing of E. coli, while ozone and superoxide scavengers made little difference. See Adding Iodide to Plasma-Activated Water: Faster Kills, a Proposed Hypoiodous Acid Mechanism, and a Salmonella Exception (McClenaghan et al., 2025).

Which species does the killing?

A 2018 study on three bacteriophages reports that a mix of hydrogen peroxide, nitrite and nitrate at higher levels than its plasma-treated water contained gave only 1.6 to 3 orders of inactivation, while singlet oxygen scavengers almost entirely blocked the effect of both plasma and treated water. The authors conclude singlet oxygen played the primary role; see Singlet Oxygen as the Virus-Killing Agent: Plasma and Plasma-Activated Water Against Three Bacteriophages (Guo et al., 2018).

Related

• Singlet Oxygen as the Virus-Killing Agent: Plasma and Plasma-Activated Water Against Three Bacteriophages (Guo et al., 2018) — spin-trap measurements and scavenger tests pointing to singlet oxygen in virus inactivation.
• Adding Iodide to Plasma-Activated Water: Faster Kills, a Proposed Hypoiodous Acid Mechanism, and a Salmonella Exception (McClenaghan et al., 2025) — spark versus glow chemistry, scavenger assays, and iodide's effect on peroxide and nitrate levels.
• What Plasma Does to Tap Water: Sixteen Measured Species, a Conductivity Check and a Lentil Trial (Judée et al., 2018) — time courses for hydrogen peroxide, nitrite, nitrate and ammonium in treated tap water.
• The Neutralization Problem: Why Plasma-Activated Water Kill Rates May Be Overstated — measured persistence of ozone, hydrogen peroxide, nitrite and nitrate, and why it complicates efficacy testing.
• Plasma-Activated Water (PAW) — the medium in which these species are generated.
• Non-Thermal Plasma (Cold Atmospheric Plasma) — the discharge that produces them.
• chemistry, water — broad subject guides.