Air purifiers are often sold as a powerful shield against viruses and indoor pollution. Nevertheless, a comprehensive new review published in The Annals of Internal Medicine suggests that most of these claims are unused, especially when it comes to protecting people.

Researchers at the University of Colorado University, along with two US government science agencies, analyzed almost a century research on indoor air cleaning technologies.

The team examined 672 studies published between 1920 and 2023, covering the HEPA filter, ultraviolet light, advanced ventilation design, and intervention such as new microbi-killing devices.

Most studies left people

The review found that when these techniques are designed to prevent viruses from spreading indoors, when these techniques are designed from spreading indoors, very few have been evaluated in humans.

Only 8% of studies tested whether they have reduced infection in people. The overwhelming majority, more than 90%, depended on the air samples or animals used such as guinea pigs and mice in empty rooms.

For example, 44 studies had examined photochelitic oxidation, but only one tested its impact on human infections.

Plasma-based air cleaner was evaluated in 35 studies, none of which were involved. Similarly, 43 studies tested an enlarged filter with nanometrics designed to trap and kill germs, but again, no one evaluated their impact on real human health results.

“To effectively prevent infections such as Covid-19 or seasonal flu in indoor settings, the most important remedies remain proper hand hygiene, wearing masks, and maintain social disturbances. While air cleaner can support overall indoor air quality, it is unworthy and unnecessary to rely alone to prevent them, it is unwilling and unnecessary.

Why does it matter

The Covid-19 epidemic showed how disruptive aerial infections may occur, claiming millions of people, making health systems heavy, and closing schools and workplaces.

Improvement in ventilation and purifying the shared places became a public health priority. The idea, of course, is hypnotized: filters, ultraviolet light, and air-cleaning equipment can work quietly in the background, protect people without the need for continuous efforts.

If effective, they can save life in future epidemic by reducing the economic decline.

But researchers say that perfect bases still matter more.

“When it comes to infection control, we cannot consider these systems as a standard requirement in homes, schools, or even hospitals. Priority should be on proven preventive measures such as mask use, proper ventilation and vaccination,” Dr. Maurya says.

Evidence interval and consumer caution

Despite the bold marketing claims from companies, the review warns that the base of the evidence is thin when it comes to show how air purifiers protect people.

Many devices are already in use in day-to-day centers, schools, clinics and offices, but without rigorous testing.

“Air purifiers can be considered under special circumstances, such as when there are high risk individuals, for example, patients with asthma, COPD, or interstitial lung disease, especially if the outer air pollution levels are very high. In such cases, air purifiers can provide additional benefits, but they are not necessary for all,” Dr. Maurya says.

potential risk

The review also flagged off potential loss. Some technologies, such as photochettic oxidation or plasma-based systems, may release chemicals affecting indoor quality.

Dr. Mauryan adds a note of caution, especially with UV-based purifiers: “Inappropriate use of these systems may lead to the release of ozone or other harmful gases, possibly leading to respiratory irritation, cough, or other health problems. In some cases, the rays emitted may also be harmful if the device is not designed or operated properly.”

Regulation requirement

The study authors widely say for more rigorous, human-focused studies before adoption.

Further research is necessary because many of these devices are rapidly entering the market, which are inspired by increasing air pollution and the risk of viral infections such as Kovid -19.

However, they should not be used indiscriminately. “Individuals should consult a doctor or a specialist to determine whether such devices are really needed and if yes, what kind of suitable is,” Dr. Maurya agrees.

What can people do now?

Until strong evidence comes, experts recommend sticking to measures that are already proven.

For everyday concerns about indoor infections, the most important approach is to follow established preventive measures.

“If someone develops symptoms like cough, sneezing, or fever indoors, they should be encouraged to isolate, wear masks and maintain proper hand hygiene and social disturbances.”