RATIONALE Zinc oxide is a common, biologically active constituent of particulate air pollution as well as a workplace toxin. Ultrafine particles (< 0.1 microm diameter) are believed to be more potent than an equal mass of inhaled accumulation mode particles (0.1-1.0 microm diameter). OBJECTIVES We compared exposure-response relationships for respiratory, hematologic, and cardiovascular endpoi...

Recently it was speculated that ultrafine particles (UFP) may translocate from deposition sites in the lungs to systemic circulation and whether long-term clearance differs between ultrafine and micrometer-sized particles. We have studied lung retention and clearance kinetics in 12 healthy male adult WKY rats up to 6 mo after an inhalation of (192)Ir-radiolabeled, insoluble, ultrafine 15- to 20...

Silica is one of the most abundant compounds found in nature. Immoderate exposure to crystalline silica has been linked to pulmonary disease and crystalline silica has been classified as a Group I carcinogen. Ultrafine (diameter <100 nm) silica particles may have different toxicological properties compared to larger particles. We evaluated the effect of ultrafine silica nanoparticles on mouse b...

Diamond coatings made by processes such as chemical vapor deposition (CVD) have been increasingly explored for cutting tools applications, in particular, for machining lightweight high-strength materials. However, most literature to date reported that the wear resistance of CVD diamond tools is still distant to the polycrystalline diamond (PCD) counterparts. Recently, a microwave plasma-assiste...

Hexagonal close-packed (hcp) iron carbides play an important role in steel processing and in steel products. The recent discovery of novel ultrafine (2-5 nm) iron carbide (ε'-Fe2+xC) precipitates in TRIP steel sheds a new light on the hcp family of carbides. Here we present a first-principles study on the relative stability, and the electronic, magnetic properties of the ε'-Fe2C phases. Differe...

Ionization air purifiers are increasingly used to remove aerosol particles from indoor air. However, certain ionization air purifiers also emit ozone. Reactions between the emitted ozone and unsaturated volatile organic compounds (VOC) commonly found in indoor air produce additional respirable aerosol particles in the ultrafine (<0.1 microm) and fine (<2.5 microm) size domains. A simple kinetic...

We have previously shown that underground railway particulate matter (PM) is rich in iron and other transition metals across coarse (PM10-2.5), fine (PM2.5), and quasi-ultrafine (PM0.18) fractions and is able to generate reactive oxygen species (ROS). However, there is little knowledge of whether the metal-rich nature of such particles exerts toxic effects in mucus-covered airway epithelial cel...

Toxicological studies have provided evidence of the toxicity of ultrafine particles (UFP), but epidemiological evidence for health effects of ultrafines is limited. No quantitative summary currently exists of concentration-response functions for ultrafine particles that can be used in health impact assessment. The goal was to specify concentration-response functions for ultrafine particles in u...

PM10 is a complex mixture of particles and we have focused here on the ultrafine component, i.e. particles with a diameter of less than 100 nm. In PM10 this fraction is mostly composed of combustion-derived, carbon-centred particles with associated hydrocarbons and metals. Progress in understanding the effects of ultrafine particles in the lungs has been achieved largely through the use of surr...

Underground railway stations are known to have elevated particulate matter (PM) loads compared to ambient air. As these particles are derived from metal-rich sources and transition metals may pose a risk to health by virtue of their ability to catalyze generation of reactive oxygen species (ROS), their potential enrichment in underground environments is a source of concern. Compared to coarse (...