Use of air-cleaning devices to create airborne particle-free spaces intended to alleviate allergic rhinitis and asthma during sleep.

Department of Mechanical Engineering, Laboratory for Heat Transfer and Fluid Flow Practice, University of Minnesota, Minneapolis, MN 55455-0111, USA.
Indoor Air (Impact Factor: 4.2). 01/2006; 15(6):420-31. DOI: 10.1111/j.1600-0668.2005.00387.x
Source: PubMed

ABSTRACT Comprehensive quantitative experiments were performed to assess the capabilities of several air-cleaning devices to create a particle-free microenvironment as a therapy for sleeping persons affected by allergic rhinitis and asthma. Six devices were evaluated, of which five were portable and intended to provide general air cleaning for bedroom-sized spaces. The sixth was intended for installation in front of the headboard of a bed and was designed to provide clean air focused in a space occupied by a sleeping person. The air-cleaning methods of the selected devices included high-efficiency particulate air (HEPA) filtering and electrostatic precipitation. Particle concentration measurements for six particle-size ranges and sound intensity measurements were made during 8-h, sleep-simulating periods. The effects of four parameters were studied: (i) device location, (ii) controlled air motion in the laboratory, (iii) airflow rate setting of the air-cleaning device, and (iv) controlled disturbances. To ensure a totally objective study, a special laboratory facility was constructed which enabled complete control of the experimental conditions. The measured concentration histories provided comprehensive evidence of the relative capabilities of the various devices for the specific air-cleaning function. It was found that the device designed to focus the cleaned air in the sleeping space fulfilled its goal and, in that regard, was clearly superior to all of the other air-cleaning devices. PRACTICAL IMPLICATIONS: There is evidence that allergic reactions are triggered by the presence of airborne particles and that these reactions can be mitigated by particle removal. This strategy can be implemented by the use of air-cleaning devices which are capable of creating particle-free zones at locations where human activity occurs. In particular, the creation of a particle-free zone which encompasses the breathing space of a sleeping person holds promise of mitigating sleep-disturbing allergic reactions.

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    • "The concentration of particles indoors can be reduced by installing electrostatic deposition air cleaners, particulate collection devices that remove particles from a flowing gas (such as air) using the force of an induced electrostatic charge. Electrostatic air cleaners are able to remove small airborne particles very effectively (Mattsson et al. 2004; Croxford et al. 2000; Skulberg et al. 2005), including allergenic particles (Hacker and Sparrow 2005; Francis et al. 2003; van der Heide et al. 1999), whose concentrations in school classrooms are often as high as they are in the homes of pet owners (Almqvist et el. 1999; Berge et al. 1998). "
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    ABSTRACT: Two independent field intervention experiments involving a total of about 190 pupils were carried out in winter and early spring of 2005 in five pairs of mechanically ventilated classrooms that received 100% outdoor air. Each pair of classrooms was located in a different school. Electrostatic air cleaners were installed in classrooms and either operated or disabled to modify particle concentrations while the performance of schoolwork was measured. In one school, the used supply-air filters in a ventilation system without recirculation were also replaced with new ones to modify classroom air quality, while the filters in use in other schools were not changed. The conditions were established for one week at a time in a blind crossover design with repeated measures on ten-to-twelve-year-old children. Pupils performed six exercises exemplifying different aspects of schoolwork as part of normal lessons and indicated their environmental perceptions and the intensity of any symptoms. A sensory panel of adults judged the air quality in the classrooms soon after the pupils left. Operating the electrostatic air cleaners considerably reduced the concentration of particles in the classrooms. The effect was greater the lower the outdoor air supply rate. There were no consistent effects of this reduction on the performance of schoolwork, on the children's perception of the classroom environment, on symptom intensity, or on air quality as perceived by the sensory panel. This suggests there are no short-term (acute) effects of particle removal outside the pollen season. When new filters were installed, the effects were inconsistent, although this is believed to be due to sequential and unbalanced presentation of filter conditions and to the fact that the used filters retained very little dust.
    HVAC&R RESEARCH 05/2008; 14(3-3):327-344. DOI:10.1080/10789669.2008.10391012 · 0.75 Impact Factor
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    • "An idea for increasing the effectiveness of air cleaners by mounting it on the headboard and blowing the cleaned air directly over sleepers' heads was tested in several studies (Villaveces et al., 1977, Zwemer and Karibo, 1973). Although very high effectiveness was claimed in some of these studies (Verrall et al., 1988, Morris et al., 2006), funding was sometimes supplied by manufacturers and some authors (Morris et al., 2006, Hacker and Sparrow, 2005) were affiliated with the companies that manufactured the device. There was also poor study design (no blinding, no placebo) in some of these studies. "
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    ABSTRACT: Introduction We breathe about 13 cubic meters of air each day, and many of the particles in the air deposit in our lungs. Hundreds of studies worldwide have documented increases in morbidity and mortality associated with increases in particle levels outdoors. However, people spend almost 90% of their time indoors, and indoor air has its own list of sources that may be as bad or worse than outdoors—for example, cigarette smoke. Therefore much interest lies in developing ways to clean indoor air. One way to improve indoor air quality is to use an air cleaner. Air cleaners have been sold for many years, but it is important to evaluate their effectiveness in reducing pollutants in the home. Therefore Health Canada has sponsored this review of the effectiveness of air cleaners in homes. Although pollutants include gases as well as particles, this review concentrates on particle air cleaners.
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    ABSTRACT: A zero-pressure-drop, ozone-free air purification technology is reported. Contaminated air was directed into a chamber containing an array of electrospray wick sources. The electrospray sources produce an aerosol of tiny, electrically charged aqueous droplets. Charge was transferred from the droplets onto polar and polarizable species in the contaminated air stream and the charged contaminants were extracted using an electric field and deposited onto a metal surface. Purified air emerged from the other end of the chamber. The very small aqueous electrospray droplets completely evaporate so that the process is essentially dry and no liquid solvent is collected or recirculated. The air purification efficiency was measured as a function of particle size, air flow rate, and specific system design parameters. The results indicate that the electrospray-based air purification system provides high air purification efficiency over a wide range of particle size and, due to the very low power and liquid consumption rate, can be scaled up for the purification of arbitrarily large quantities of air.
    Journal of Applied Physics 12/2007; 102(11):113305-113305-6. DOI:10.1063/1.2818364 · 2.19 Impact Factor
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