Can Portable Air Cleaners Remove Particulate Pollutants In Our Homes and Offices?
Angela Southey PhD discusses the potential health benefits of these popular products
Portable air cleaner usage in homes and offices has increased steadily over the last 20 years in countries such as the US where one in three households has an air cleaner 1. The main reason for this is heightened public awareness of the harmful health effects of particulates. In China, domestic air purifiers were almost unheard of prior to 2013 2. Now in many parts of Asia, air purifier sales are booming 2 as more and more citizens suffer from respiratory problems due to chronic air pollution and smog in their cities leading to deterioration in indoor air quality.
Particulate pollutants, found both indoors and outdoors, come from many sources such as burning of materials (e.g. wood, coal, and tobacco 3), motor vehicle exhausts, household cleaning products and asbestos fibers. Particulate pollutants can also come from biological sources including pollen, pet dander, dust mite allergens, mould spores, bacteria and viruses. Particulate pollutants can cause cough, nasal irritation, lung infection, chronic lung conditions, cancer and premature death 3. They are also associated with allergic respiratory diseases, such as bronchial asthma. The prevalence of asthma and allergies has increased in the last decade, which may be explained by changes in environmental factors, including indoor and outdoor air pollution 4.
Particulate matter of 10 µm or less in diameter (PM10) is small enough to be inhaled (inhalable) and can accumulate in the respiratory tract 3. PM10 particles include house dust mite allergen, pollen, textile and asbestos fibres. PM10 were the main focus of air cleaner technology when these devices were initially developed in the 1970’s 1.
Particulate matter of 2.5 µm in diameter or less (PM2.5), only 1/10,000 of an inch, is now considered more hazardous to health than PM10 as such particles are small enough to be inhaled deeply to the periphery of the lungs (respirable) and can enter the bloodstream 3. PM2.5 and below consist of particulates from tobacco and combustion smoke, lead dust, auto emissions, bacteria such as Legionella and viruses including influenza. Long-term exposure to PM2.5 particles has been linked to cancer and heart disease 2,3. The people most at risk are individuals with asthma, influenza, lung, heart, or cardiovascular disease, the elderly and children 3.
The most effective way to reduce exposure to indoor pollutants is to control the pollutant emissions or eliminate the sources of pollution 5. In addition to source control, adequate ventilation of the area with clean outdoor air is recommended 5. However, ventilating the space may be limited by prevailing weather conditions or undesirable levels of outdoor pollutants. If these measures are insufficient to resolve indoor air quality problems, individuals are likely to benefit from the introduction of systems demonstrated to effectively remove noxious particulate material 5. Portable devices in indoor spaces with proven air cleaning technologies, providing they are installed and maintained according to manufacturer’s instructions, have the potential to significantly reduce air pollution.
- determination of whether an air cleaner is capable of removing/inactivating identifiable and measurable particulate pollutants including
- verification of device manufacturer’s claims
- contribution to consumer empowerment allowing informed choice, of particular relevance for individuals with asthma, allergic sensitivities or those who are immune-impaired.
It is important to realise that, despite the increased demand for portable air purifiers, there is no international standard available for testing their ability to remove airborne particulates and gaseous pollutants. Instead, many countries use their own standard test methods to evaluate the performance of such devices. The main standardised test methods cited in the literature are ANSI/AHAM AC-1 in the USA; JEM 1467 and JIS C 9615 in Japan; GB/T 18801-2015, GB 21551.3-2010 and GB/T 18883-2002 in China and SPS-KACA 002-132 in Korea. At airmid healthgroup we provide testing in line with all the relevant national standards.
Many of these national standards have identifiable shortcomings including their focus on tobacco smoke, high indoor pollution loads and a failure to take account of production of secondary harmful products such as aldehydes and ozone by oxidising techniques and high voltage electronic filters 6. Unfortunately, none of the standards mentioned in this article address some very important bioaerosol exposures such as virus inactivation/removal, a particular area of expertise for airmid healthgroup.
HEPA (High Efficiency Particulate Arresting) and activated carbon are commonly used technologies in air purifiers due to their efficiency at trapping particulates and harmful gases 7,8,9. The Institute of Environmental Science and Technology (IEST) defines True HEPA filters as having a ‘minimum particle collection efficiency of 99.97% on 0.3 µm particles of specified aerosol 7,8. True HEPA filters must meet stringent standards to be called HEPA 8. One problem encountered in the air cleaner market according to Sublett et al. 10 is the "inappropriate use of the term HEPA," where lower cost filters are used in place of true HEPA filters and may be called HEPA-type and HEPA-like. Sublett et al. says this "falsely implies that these products meet the performance requirements’’ 10.
The issues identified in this article are frequently addressed by airmid healthgroup and other testing laboratories. Experience in such companies clearly indicates that some, but not all, marketing claims are verifiable and underlines the importance of a process involving independent third party claim verification of products using a wide range of technologies.
Article by Angela Southey PhD MPH, Manager - Indoor Health Innovation
1. Shaughnessy, R.J. and Sextro, R.G. (2006). What is an effective portable air cleaning device? A review. Journal of Occupational and Environmental Hygiene 3: 169-181.
2. Fullerton J (2016). China’s anti-pollution tech is booming, but it can’t make dirty air go away
3. Particulate matter: Little things can cause big problems. Hamilton County Environmental Service, Air Quality Management Division.
4. D’Amato, G. et al. (2005). Environmental risk factors and allergic bronchial asthma. Clinical Experimental Allergy 35(9): 1113-24.
5. Indoor Air Quality – Guide to Air Cleaners in the Home. EPA 402-F08-004, May 2008.
6. Ginestet, A. (2012). Development and evaluation of a new test method for portable air cleaners (CR 15) (AIVC) Air infiltration and Ventilation Centre.
7. EPA. (2009) Residential Air Cleaners (Second Edition): A Summary of Available Information. (EPA 402-F-09-002) United States Environmental Protection Agency.
8. TechSci Research Press Release. Mar 2016. HEPA Filters Market to Cross $2.7 billion in 2016.
9. TechSci Research Press Release. Jun 2016. China Air Purifiers Market Set to Grow at CAGR 18% till 2021.
10. Sublett, J.L. et al. (2010) Air filters and air cleaners: Rostrum by the American Academy of Allergy, Asthma & Immunology Indoor Allergen Committee. The Journal of Allergy and Clinical Immunology 125 (1), 32-38.