Indoor air purifiers: their effectiveness remains to be demonstrated
Today ANSES is publishing the results of its analysis of air purification techniques based on the principles of plasma, catalysis and photocatalysis, ozone generation and ionisation. Over the last few years, equipment has appeared on the market that claims to have indoor air purification properties, along with "depolluting" building and decorating materials designed to trap or destroy many microbiological and chemical contaminants of indoor air. In its expert appraisal, the Agency emphasises that the available data were unable to demonstrate the effectiveness and safety in real conditions of use of the indoor air purification devices based on these technologies. It also reiterates that to reduce exposure to indoor air pollutants, priority should be given to limiting emissions at the source, and aerating and ventilating the indoor areas of buildings.
The indoor environment is characterised by a wide range of exposures to many microbiological and chemical contaminants, whose consequences on health vary, in particular depending on the type of pollutants, the characteristics of exposure, etc.
Over the last few years, a market has developed in the area of indoor air purification with the sale of equipment claiming to have indoor air purification properties in the form of stand-alone units, as well as building and decorating materials offering depolluting properties. These devices and products are intended for the entire population, but may specifically target sensitive or sensitised individuals, such as those with asthma or allergies. However, the issue of their effectiveness, and more importantly their safety, is regularly raised.
In this context, ANSES issued an internal request to identify and analyse the new indoor air purification techniques. The aim of this work was to assess the effects of using these various devices on air quality, in other words, to analyse the pollutants effectively treated and the pollutants potentially emitted by this equipment.
Agency conclusions and recommendations
The Agency first reiterates that to reduce exposure to indoor air pollutants, it is important to begin by limiting emissions at the source, and aerating and ventilating the indoor areas of buildings.
In view of the results of its expert appraisal, ANSES emphasises that overall, the scientific data collected and analysed were unable to demonstrate the effectiveness and safety in real conditions of use of indoor air purification devices based on the principles of catalysis or photocatalysis, plasma, ozone generation or ionisation.
The Agency recommends implementing certification for indoor air purification devices, with testing being conducted in conditions that are as similar as possible to the actual conditions of use of these devices.
Concerning the specific case of sprays claiming a biocidal action, when these products are assessed in the framework of the biocidal products marketing authorisation process, ANSES recommends paying special attention to scientific data on the health effects associated with inhalation of the natural or synthetic volatile organic compounds (VOCs) emitted by these sprays. This is because several VOCs (terpene VOCs for example) emitted by these products can potentially have harmful effects on health.
The question of nanoparticle emissions by certain air purification devices, specifically those using photocatalysis, was also raised during this expert appraisal. Additional research should be carried out on the emission of nanoparticles in the air by photocatalytic materials, especially as they age, along with an assessment of their safety.
The Agency also recommends informing the population that the use of certain purification devices (ozone generation, cold plasma, etc.) can lead to a deterioration in indoor air quality, as a result of incomplete degradation of pollutants leading to the formation of compounds that are potentially more harmful than those being treated.
Special care should also be exercised regarding people with asthma, due to the possible aggravation of their condition when these devices are used, especially with "cleaning" sprays and devices that may generate ozone.
Lastly, the Agency highlights the need to conduct studies on the health impact of using essential oils that can be found in many consumer goods.