Control of respirable particles in indoor air with portable air cleaners

A mass-balance indoor particle dynamic model was adopted and modified to investigate how on-roadway ultrafine particle (UFP, diameter < 100 nm) concentrations and vehicle ventilation settings affect UFP levels inside vehicles. The model was first parameterized focusing on a mechanistic, simulation-based interpretation of in-cabin data reported in Zhu et al. Under condition (3), the effects of penetration factor, deposition coefficient, and vehicle speed were comparable. The modeled I/O ratio was inversely proportional to the airflow rate from mechanical ventilation in the whole range (0-360 m 3 h −1 ) with 10-20% influence depending on the particle size.

Section: Deposition Coefficient (␤)mentioning

confidence: 99%

Quantitative Analysis of the Parameters Affecting In-Cabin to On-Roadway (I/O) Ultrafine Particle Concentration Ratios

Zhu

2009

“…The research house is a two-story, wooden building, within which three rooms on the ground oor were weatherized to reduce the in ltration rate to below 0.1 air changes per hour (ACH, h ¡ 1 ) (Offermann et al 1985). Experiments were conducted in one of these test rooms (36 m 3 ; 3.2 £ 4.6 £ 2.4 m; Figure 1).…”

Section: Test Facilitymentioning

confidence: 99%

Evaluation of a Methodology for Quantifying the Effect of Room Air Ultraviolet Germicidal Irradiation on Airborne Bacteria

Miller¹,

Macher²

2000

ABSTRACT. As a result of the recent resurgence in tuberculosis (TB) and the increasing incidence of multidrug-resistant TB, there has been renewed interest in engineering controls to reduce the spread of TB and other airborne infectious diseases in high-risk settings. Techniques such as the use of lamps that produce ultraviolet germicidal radiation may reduce exposure to infectious agents by inactivating or killing microorganisms while they are airborne. We designed and evaluated a test method to quantitatively estimate the ef cacy of germicidal lamps, in conjunction with dilution ventilation, for reducing the concentration of viable airborne bacteria. Bacterial particles were generated in a 36 m 3 room and collected with midget impingers at 5 -7 locations. The effectiveness of the control technique was determined by comparing concentrations of culturable airborne bacteria with and without the control in operation. Results for a single, 15 W germicidal lamp showed reductions of 50% for Bacillus subtilis (B. subtilis) and Micrococcus luteus (M. luteus); tests with Escherichia coli (E. coli) showed nearly 100% reduction (E. coli were isolated only from the sampler nearest the aerosol source when the lamp was operating). The addition of louvers to a lamp greatly reduced its ef cacy. Decay experiments showed that roughly 4 -6 equivalent air changes per hour were achieved for B. subtilis with one or two lamps operating. These preliminary experiments demonstrated that this methodology was well suited for these evaluations and identi ed factors that could be modi ed to re ne the study design for future work.

“…The previous studies on particle deposition include work by Van de Vate (1972), MacMahon and Denison (1979), Offermann et al (1985), Sinclair et al (1988), Weschler and Shields (1988), Knutson (1989), Nazaroff and Cass (1989), Wu et al (1989), Xu et al (1994), Cheng Y S. (1997), and others.…”

Section: Introductionmentioning

confidence: 99%

Quantitative Assessment of the Effect of Surface Deposition and Coagulation on the Dynamics of Submicrometer Particles Indoors

Jamriska

Morawska

2003

Exposure to airborne particles indoors depends on particle concentration, which is affected by air filtration, ventilation, and particle dynamics. The aim of this work was quantitative assessment of the effects of coagulation, surface deposition, and ventilation on the submicrometer particle concentration indoors. The assessment was obtained from measured particle loss rate and deposition velocity parameters