Academic journal article Environmental Health Perspectives

Recirculating Air Filtration Significantly Reduces Exposure to Airborne Nanoparticles

Academic journal article Environmental Health Perspectives

Recirculating Air Filtration Significantly Reduces Exposure to Airborne Nanoparticles

Article excerpt

BACKGROUND: Airborne nanoparticles from vehicle emissions have been associated with adverse effects in people with pulmonary and cardiovascular disease, and toxicologic studies have shown that nanoparticles can be more hazardous than their larger-scale counterparts. Recirculating air filtration in automobiles and houses may provide a low-cost solution to reducing exposures in many cases, thus reducing possible health risks.

OBJECTIVES: We investigated the effectiveness of recirculating air filtration on reducing exposure to incidental and intentionally produced airborne nanoparticles under two scenarios: while driving in traffic, and while generating nanomaterials using gas-phase synthesis.

METHODS: We tested the recirculating air filtration in two commercial vehicles when driving in traffic, as well as in a nonventilation room with a nanoparticle generator, simulating a nanomaterial production facility. We also measured the time-resolved aerosol size distribution during the in-car recirculation to investigate how recirculating air filtration affects particles of different sizes. We developed 3 recirculation model to describe the aerosol concentration change during recirculation.

RESULTS: The use of inexpensive, low-efficiency filters in recirculation systems is shown to reduce nanoparticle concentrations to below levels found in a typical office within 3 min while driving through heavy traffic, and within 20 min in a simulated nanomaterial production facility.

CONCLUSIONS: Development and application of this technology could lead to significant reductions in airborne nanoparticle exposure, reducing possible risks to health and providing solutions for generating nanomaterials safely.

KEY WORDS: automobile, filtration, nanoparticle exposure, prevention, workplace. Environ Health Perspect 116:863-866 (2008). doi:10.1289/ehp.11169 available via [Online Online 26 March 2008]

Research over the past 15 years has demonstrated a close association between inhalation of airborne particles and increased pulmonary and cardiovascular disease (Mills et al. 2007; Pope and Dockery 2006; Seaton et al. 1995). Substantial attention has been given to airborne particulate matter < 2.5 [[micro]m (Dockery et al. 1993), yet there is increasing evidence that particles < 100 nm in diameter--referred to as ultrafine particles (UFPs) or nanoparticles--may play an important role in determining the health impact of inhaled aerosols (Oberdorster et al. 2007). Several studies have demonstrated that the potency of inhaled nanoparticles can be associated with size-related parameters, including surface area, rather than the more conventional exposure metric of mass concentrarion [reviewed by Oberdorster et al. (2005)]. Moreover, by virtue of their size, nanoparticles have the potential to move from the portal of entry (e.g., the respiratory tract) to secondary organs usually inaccessible to inhaled particles, including the brain (Elder et al. 2006; Oberdorster and Utell 2002; Semmler et al. 2004). They may also perturb key biologic processes, resulting in protein misfolding (Linse et al. 2007), a pathology involved in neurodegenerative disorders.

Some of the highest potential exposures to nanoparticles occur in cars, while driving and standing in heavy traffic. A recent study estimated that 33-45% of total UFP exposure for Los Angeles, California, residents occurs when traveling in vehicles (Fruin et al. 2008). Epidemiologic data show an association between exposure in traffic and the onset of a myocardial infarction within 1 hr afterward (Peters et al. 2004), and a recent study shows brief exposure to combustion-derived nanoparticles to promote myocardial ischemia in men with stable coronary disease (Mills et al. 2007). Emissions and exposure are dominated by nanoscale particles: Approximately 90% of emitted particles from diesel-powered cars on the road measure between 5 nm and 300 nm (Kittelson et al. …

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