While wildfires continue to burn across Canada and parts of the United States, causing widespread air quality alerts in over 20 US states, concerns about air pollution and its impact on health are growing. This has led to increased interest in indoor air purifiers, particularly as outdoor pollutants can significantly affect indoor air quality. Historically, air quality in the US had been improving, with a decline in fine particulate matter (PM2.5) in many states before 2016. However, the escalating frequency and intensity of wildfires are reversing this progress.
Indoor air pollution can exacerbate existing respiratory conditions such as asthma, trigger allergies, and contribute to 'sick building syndrome,' which manifests with symptoms like fatigue, headaches, and nausea. Consequently, the market for indoor air purifiers is experiencing substantial growth, with projections indicating a near doubling in the US market from £2.2 billion in 2022 to £3.8 billion by 2030. For UK residents, understanding how these devices work and their potential benefits is becoming increasingly relevant.
Air purifiers are primarily portable, mechanical devices designed to capture particulate matter from the air. While commonly referred to as 'purifiers,' experts often prefer the term 'air cleaners' as most at-home units filter rather than 'purify' in the sense of eliminating all viruses or bacteria, unless equipped with additional technologies like germicidal UV light. The core of most effective air cleaners is a High-Efficiency Particulate Air (HEPA) filter, which can remove 99% of particles as small as 0.3 microns. These include common allergens like dust, pollen, and pet dander, as well as some bacteria and the fine particles found in smoke.
Beyond HEPA filters, some devices also incorporate carbon filters, which are particularly effective at trapping odours, gases, and volatile organic compounds (VOCs). However, consumers should be aware that some older or less reputable devices may use ionisers, which, while reducing dust, can produce ozone gas – a known lung irritant. The overall effectiveness of an air cleaner hinges on several factors: the quality of its filtration system, its size relative to the room it's intended to clean, and its Clean Air Delivery Rate (CADR), which indicates how much filtered air the unit delivers per minute.
For optimal performance, regular maintenance, particularly changing filters as recommended by the manufacturer, is crucial. The cost of replacement filters can sometimes be substantial, so it's advisable to factor this into the initial purchase decision. While air cleaners can improve indoor air quality, they should ideally be used in conjunction with regular household cleaning practices and, when outdoor air quality permits, at least 10 minutes of daily ventilation. Individuals with respiratory conditions, allergies, cardiovascular issues, as well as children, pregnant people, and the elderly, are generally considered the primary beneficiaries of these devices.