February 15, 2025
New Study Finds No Convincing Evidence that Air Purifiers Prevent Respiratory Infections

New Study Finds No Convincing Evidence that Air Purifiers Prevent Respiratory Infections

The COVID-19 pandemic has spurred a growing interest in improving indoor air quality to mitigate the spread of the virus. However, a recent study conducted by researchers has revealed that there is no compelling evidence to suggest that air purifiers effectively reduce the risk of respiratory infections.

The study, which was a systematic review of previous research conducted between 1970 and 2022, examined the effectiveness of two common types of air treatment devices: filters and air disinfectors. Filters work by removing particles from the air that may contain infectious viruses, while air disinfectors use ultraviolet radiation or ozone to inactivate viruses in the air.

The review analyzed 32 observational and experimental studies and found that overall, air treatment technologies did not reduce the frequency or severity of illness from respiratory infections. Although there appeared to be a trend towards fewer laboratory-confirmed influenza or norovirus infections, the researchers noted evidence of publication bias, where positive results are more likely to be published than negative results. This bias can skew the perceived impact of any intervention or treatment, making it appear more effective than it actually is.

It is important to note that none of the studies included in the review directly examined the effectiveness of air treatment technologies against COVID-19, as they were conducted prior to the pandemic. However, a recent German study published in July examined the impact of high-efficiency particulate air (HEPA) filters on COVID-19 in kindergartens. Surprisingly, the study found no significant difference in infection rates between schools with newly installed filters and those without. In fact, infection rates were slightly higher in schools with filters.

The German study did not take into account the effect of ventilation, such as keeping windows open, on the risk of illness. It is possible that the reduction in ventilation rates during the use of air treatment technologies could increase the risk of infection.

In addition to this review, there has been a separate systematic review examining the effect of ventilation on COVID-19 infection. Although there was some evidence to support the role of ventilation in reducing infection rates, the quality of the studies was generally poor. Consequently, the researchers concluded that the level of confidence in the effectiveness of ventilation is low.

Despite these findings, it is worth considering why air treatment technologies may not have been the ultimate solution that was initially believed. Firstly, the risk of respiratory virus transmission largely depends on proximity to an infected person. Previous research has shown that the risk of infection decreases significantly as one gets further away from an infected individual. Therefore, it is unlikely that air treatment technologies would have a significant impact on close person-to-person transmission.

Furthermore, even if air treatment was effective in preventing infection within a specific indoor space, individuals regularly move between different environments, such as public transportation or social gatherings. Thus, relying solely on air treatment in a particular location would not provide protection in all scenarios.

Lastly, the dynamics of infectious diseases with a short duration of immunity, like COVID-19, differ from those predicted by standard epidemic models. These diseases are better modeled by the SEIRS (susceptible, exposed, infected, recovered, susceptible) model, where interventions such as air filtration or mask-wearing become less effective over time due to reinfections. The rate at which individuals lose their immunity becomes the driving factor behind infection rates.

In conclusion, the current real-world evidence suggests that air treatment technologies do not effectively reduce the risk of respiratory infections, including COVID-19. While there is some evidence supporting increased ventilation’s potential in reducing the risk, the overall evidence is not yet compelling. As the pandemic continues, further research is necessary to explore alternative strategies for mitigating the transmission of respiratory infections.

*Note:
1. Source: Coherent Market Insights, Public sources, Desk research
2. We have leveraged AI tools to mine information and compile it

Ravina
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Ravina Pandya,  Content Writer, has a strong foothold in the market research industry. She specializes in writing well-researched articles from different industries, including food and beverages, information and technology, healthcare, chemical and materials, etc. With an MBA in E-commerce, she has an expertise in SEO-optimized content that resonates with industry professionals.

Ravina Pandya

Ravina Pandya,  Content Writer, has a strong foothold in the market research industry. She specializes in writing well-researched articles from different industries, including food and beverages, information and technology, healthcare, chemical and materials, etc. With an MBA in E-commerce, she has an expertise in SEO-optimized content that resonates with industry professionals.

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