Uncertainty Surrounds the Safety and Effectiveness of Popular Air Cleaning Devices

Portable air cleaning devices are increasingly used to combat indoor spread of respiratory infections, including viruses like COVID-19 and influenza. These devices, which include HEPA filters, ultraviolet light systems, and specialized ventilation, are designed to purify indoor air and reduce the risk of infection. However, a comprehensive review published in the journal Annals of Internal Medicine highlights a significant gap in our understanding: most of these devices have not been thoroughly tested on people, and very little is known about their potential health harms.

In an analysis of nearly 700 studies spanning from the 1920s to 2023, researchers found that only around 8% evaluated the effectiveness of air cleaning technologies directly on individuals. The vast majority of studies tested these devices in empty rooms or on animals, using air samples to measure reductions in particles or microbes, but without assessing real-world health outcomes. For instance, technologies like photocatalytic oxidation and plasma-based sterilization were examined, yet none of these studies involved human participants.

The importance of this issue became clear during the COVID-19 pandemic, which demonstrated how airborne infections can cause widespread health crises, overwhelm healthcare systems, and lead to significant loss of life. Efforts to improve indoor air quality aim to mitigate these risks, but without robust evidence demonstrating the safety and real-world efficacy of the devices, consumer and institutional reliance on certain products remains questionable.

Additionally, some air purifying technologies produce harmful chemicals such as ozone, formaldehyde, and hydroxyl radicals. These substances can pose health risks if inhaled, yet only a small fraction of studies have evaluated potential toxic byproducts. This creates a problem: while companies promote air cleaners for infection control, the lack of safety testing raises concerns about unintended health consequences.

Furthermore, standardization in testing and monitoring effectiveness and safety is absent. It is crucial to evaluate these devices in settings involving actual human exposure and to assess the formation of harmful byproducts. Only through rigorous, real-world investigations can we better determine which technologies genuinely protect health without causing harm.

In summary, although air cleaning devices hold promise for reducing indoor transmission of respiratory infections, their widespread use must be guided by evidence. Current research indicates that most products lack comprehensive testing on humans and safety assessment, underscoring the need for more thorough evaluation before they become universal solutions.

Source: https://medicalxpress.com/news/2025-08-air-devices-people-potential.html