Ozone (O₃) is a highly reactive gas with a pungent odor. It exists naturally and as a byproduct of human activities. This powerful oxidizing agent inactivates viruses. This article explores how ozone interacts with viruses, its real-world effectiveness, and safety considerations for human exposure.
How Ozone Interacts with Viruses
Ozone inactivates viruses through its strong oxidizing properties. It directly attacks and damages essential viral components. For enveloped viruses, such as coronaviruses, ozone targets this protective lipid layer. It causes peroxidation of lipids and destruction of envelope proteins, including glycoproteins vital for attachment to host cells.
Even for non-enveloped viruses, ozone can still be effective. It damages the proteins that form the viral capsid and can also directly attack the viral genetic material, whether DNA or RNA. Viruses lack enzymatic defenses against oxidative stress, making them vulnerable to ozone’s destructive action. This damage prevents the virus from replicating or infecting new host cells.
Real-World Effectiveness of Ozone Against Viruses
The effectiveness of ozone depends on several factors, including concentration, exposure duration, humidity, and the presence of organic matter. While ozone can be highly effective in controlled laboratory settings with high concentrations, its practical application for viral inactivation in occupied spaces is significantly limited.
Ozone is widely utilized in water purification, including municipal water treatment and swimming pools. In these environments, ozone concentrations are precisely controlled to kill viruses and other microorganisms, with human exposure managed or absent during treatment. However, using ozone for air purification where people are present is problematic. Concentrations safe for human breathing are too low to effectively inactivate airborne viruses. Ozone can also react with other chemicals in the air, forming new harmful pollutants.
Safety Considerations for Ozone Exposure
While ozone is effective against viruses, it is also a powerful oxidant posing significant health risks to humans and animals. Even at low concentrations, inhaling ozone can cause respiratory irritation, causing symptoms like coughing, chest tightness, shortness of breath, and throat soreness. Prolonged or repeated exposure can result in lung damage and worsen existing respiratory conditions like asthma. Eye irritation and headaches are common effects.
Because of these health concerns, ozone is recognized as a regulated air pollutant by agencies like the Environmental Protection Agency (EPA) and the Occupational Safety and Health Administration (OSHA). These bodies set standards for permissible exposure limits to protect public health and worker safety. Consequently, the use of ozone generators for air purification in homes or occupied spaces is discouraged. Such devices can easily produce ozone at levels exceeding safety guidelines, creating a health hazard rather than improving air quality.