Workers Exposures to Ultra-fine Particulate Matter during Automobile Components Production

摘要

Workers are potentially vulnerable to environmental hazards and health risks associated with the inhalation of ultra-fine airborne particles in the workplace. A few studies have reported significant exposures and health effects of ultra-fine and nanomaterials during manufacturing processes. Nanotechnology holds great promise for occupational health and safety and particulate matter is often present at nanoscale levels such that they often exhibit unique physical, chemical, and biological properties. The National Institute for Occupational Safety and Health (NIOSH) has reported that workers within nanotechnology and ultra-fine-related industries have the potential to be exposed to uniquely engineered materials at levels far exceeding ambient concentrations. The present study was conducted to investigate workers exposure levels and evaluate potential health risks during different engineering processes in an automobile components production facility. Additionally, while most studies have focused on exposure assessment based on mass concentration, this study measured and compared airborne levels of respirable particulate matter based on both number and mass concentrations. This study was conducted in the month of February 2005 and 2006 during the morning work shift. Personal airborne samples were collected with a calibrated sampling train consisting of a polyvinyl chloride (PVC) filter attached to a cyclone and a portable sampling pump. Additionally, instantaneous area samples were collected using a handheld, six-channel particle counter. The air filters were analyzed gravimetrically and the results of both personal and instantaneous sampling were analyzed using descriptive and correlation statistics. The results showed that workers exposure levels for respirable materials were below the Occupational Safety and Health Administration (OSHA) permissible exposure limits (PELs) and the American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Values. Additionally, workplace levels were higher in the afternoon than in the morning and there was variation from one year to the next. The results presented show a strong positive correlation between particle mass and number concentrations, and thus demonstrates the potential usefulness of combining both measurement techniques as exposure metric for respirable and ultra-fine industrial materials. The concentrations reported during this study are only representative of workers exposures from inhalation and may not account for ingestion and dermal exposures. Additionally, current research suggests that particle size and surface chemistry may be more important and relevant for particulate exposure measurements than mass and bulk chemistry. The implementation of well-established occupational health and safety controls is needed to reduce exposures in workplaces where potential for long-term health effects may not be well documented or understood. The study recommends preventive measures and risk reduction strategies to effectively reduce workers exposure risks, potential health effects, and ultimately manage ultra-fine particulate air pollution in the workplace.