Intercomparison in the laboratory of various Condensation Particle Counters challenged by nanoaerosols in the range 6 – 460 nm (original) (raw)
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International Journal of Nanoparticles, 2008
The accurate measurement of ultrafine and submicron sized airborne particles is a challenging task. Since several studies have linked exposures to airborne ultrafine particles to elevated human health risks, the need to assess the concentrations of particles in the workplace that are below one micron in diameter is imperative. Several techniques for directly monitoring micro and nanoparticles are available and others are being tested for their merit. Condensation Nuclei Counters (CNCs), portable condensation particle counters, differential mobility analysers, electron microscopy and other novel approaches to measuring micro and nanoparticles have been employed in investigations. The purpose of this paper is to elucidate the results from three studies involving the measurement of airborne particles with a laser particle counter and condensation nuclei counter. The three environments include: a gambling casino, a Shielded Metal Arc Welding (SMAW) operation and a general manufacturing facility with welding, cutting and grinding operations being performed.
Journal of Aerosol Science, 2007
The formation and growth of fresh atmospheric aerosol particles was investigated using a condensation particle counter battery (CPCB). This instrument is a matrix of four separate CPCs, which differ in the combination of both cut-off size and working liquid (water; n-butanol). In a first step, the CPC counting efficiencies and cut-off sizes were carefully characterised under laboratory conditions for different condensing vapours, temperature differences between condenser and saturator, and test aerosol types. In addition, the activation process was described theoretically, and modelled numerically for the given CPC configurations. These results confirmed that water-soluble and water-insoluble as well as butanol-soluble and butanol-insoluble aerosol particles may be discriminated in the CPCB through different activation diameters. Therefore, the CPCB represents a novel tool to infer information on the chemical composition of aerosol particles between 2 and 20 nm. To test the applicability of the CPCB under field conditions, the CPCB was operated at a rural background station in Finland (Hyytiälä) in April and May 2005. The results indicate that growing nucleation mode particles were water-soluble both at 3 and 11 nm. ᭧
Relevance of aerosol dynamics and dustiness for personal exposure to manufactured nanoparticles
Journal of Nanoparticle Research, 2009
Production and handling of manufactured nanoparticles (MNP) may result in unwanted worker exposure. The size distribution and structure of MNP in the breathing zone of workers will differ from the primary MNP produced. Homogeneous coagulation, scavenging by background aerosols, and surface deposition losses are determinants of this change during transport from source to the breathing zone, and to a degree depending on the relative time scale of these processes. Modeling and experimental studies suggest that in MNP production scenarios, workers are most likely exposed to MNP agglomerates or MNP attached to other particles. Surfaces can become contaminated by MNP, which constitute potential secondary sources of airborne MNP-containing particles. Dustiness testing can provide insight into the state of agglomeration of particles released during handling of bulk MNP powder. Test results, supported by field data, suggest that the particles released from powder handling occur in distinct size modes and that the smallest mode can be expected to have a geometric mean diameter [100 nm. The dominating presence of MNP agglomerates or MNP attached to background particles in the air during production and use of MNP implies that size alone cannot, in general, be used to demonstrate presence or absence of MNP in the breathing zone of workers. The entire respirable size fraction should be assessed for risk from inhalation exposure to MNP.
Particle size dependent response of aerosol counters
Atmospheric Research, 2002
During an international workshop at the Institute for Experimental Physics of the University of Vienna, Austria, which was coordinated within the Committee on Nucleation and Atmospheric Aerosols (IAMAS-IUGG), 10 instruments for aerosol number concentration measurement were studied, covering a wide range of methods based on various different measuring principles. In order to investigate the detection limits of the instruments considered with respect to particle size, simultaneous number concentration measurements were performed for monodispersed aerosols with particle sizes ranging from 1.5 to 50 nm diameter and various compositions. The instruments considered show quite different response characteristics, apparently related to the different vapors used in the various counters to enlarge the particles to an optically detectable size. A strong dependence of the 50% cutoff diameter on the particle composition in correlation with the type of vapor used in the 0169-8095/02/$ -see front matter D 2002 Elsevier Science B.V. All rights reserved. PII: S 0 1 6 9 -8 0 9 5 ( 0 2 ) 0 0 0 11 -X $ Coordinated within the Committee on Nucleation and Atmospheric Aerosols, International Commission on Clouds and Precipitation, IAMAS-IUGG.
Measurement of Ultrafine Particles: A Comparison of Two Handheld Condensation Particle Counters
Aerosol Science and Technology, 2004
The objective of this study was to compare two real-time condensation particle counters for measurement of number concentrations of ultrafine particles (UFPs). The comparison is based on the data from side-by-side measurements conducted in several locations, both indoors and outdoors. CPC 3007 and P-Trak TM 8525 manufactured by TSI (instruments A and B, respectively) were used simultaneously. They measure particles in sizes from 0.01 to greater than 1 µm and 0.02 to greater than 1 µm, respectively. The results reveal a good correlation between the two instruments. The ratios of measured aerosol concentrations varied from 0.81 to 1.17, which implies that in all data sets the difference between the two instruments was less than ±20%. About 63% of the results were in the range of ±10%, and about 44% showed differences less than ±5%. The maximum particle concentration detected by instrument A was approximately 105,000 particles cm −3 and the minimum was about 230 particles cm −3 . Because of the lower particle size threshold for instrument A, it was expected that this instrument should never show concentrations lower than those detected by instrument B. This was the case in most of the measurement series. The results revealed that the concentration of UFPs changes rapidly, especially in the presence of a local UFP source. A sampling interval of 1 min is sufficient to provide substantial information about the change in concentration level.
Validation of the condensation particle counter UF-02M in laboratory and ambient conditions
Lithuanian Journal of Physics, 2013
The main performance characteristics of the modernized condensation particle counter (CPC) UF-02M were determined. We studied the particle number concentration range of the instrument and the detection efficiency as a function of the particle diameter experimentally. In order to determine a cut-size D 50 , the function was fitted to the experimental data. According to the fitting, the cut-size was 4.35 nm. The determined cut-size allows detecting the aerosol particles of the nucleation mode, giving possibilities to find many applications of the CPC UF-02M in the investigations of the aerosol nanometre particle dynamical properties. The counting efficiency of the CPC at high particle concentrations was experimentally investigated using silver particles of a 20 nm diameter. The minimum measured number concentration of aerosol particles was 0.003 cm -3 , the maximum was 150000 cm -3 with the accuracy of 20%. The operation of the CPC UF-02M was compared with the operation of a commercially available SMPS TSI3936 under ambient conditions. The measured number concentrations were comparable with 5% accuracy. During the testing time, both instruments detected a new particle formation event. It was determined that the number concentration measured with the modernized CPC was higher than that determined by the SMPS. It was explained that a new CPC had a lower cut-size and detected smaller particles than the SMPS did.
Atmospheric Measurement Techniques Discussions, 2019
We present a microelectromechanical system (MEMS)-based condensation particle counter (CPC) for sensitive and precise monitoring of airborne ultrafine particles (UFPs) at a point of interest that is portable, inexpensive, and accurate. The proposed system consists of two main parts: a MEMS-based condensation chip that grows UFPs to micro-sized droplets and 10 a miniature optical particle counter (OPC) that singly counts grown droplets with the light scattering method. A conventional conductive cooling-type CPC is miniaturized through MEMS technology and the 3D printing technique, and the essential elements for growing droplets are integrated on a single glass slide. The proposed system is much more compact (75 mm 130 mm 50 mm), lightweight (205 g), and power-efficient (2.7 W) than commercial CPCs. In quantitative experiments, the results indicated that the proposed system can detect UFPs as small as 13.4 nm by growing them to micro-sized (3.16 µm) 15 droplets. The proposed system measured the UFP number concentration with high accuracy (deviation within 4.1 %), and its detectable concentration range of 7.99-7200 N cm −3. Thus, the proposed system can potentially be used for UFP monitoring in both low-concentration (e.g., air filtration system, high-precision industries utilizing cleanrooms) and high-concentration (e.g., indoor/outdoor atmospheres) environments. 1 Introductions 20 Monitoring of airborne ultrafine particles (UFPs), which are smaller than 100 nm, is needed in various fields for human health and yield enhancement in industrial fields(Donaldson et al., 1998; Donovan et al., 1985; Hristozov and Malsch, 2009). UFPs are mainly generated from burning fossil fuels and are ubiquitous in urban air; they account for about 90% of the total particle number concentration(Kittelson, 1998; Shi et al., 1999). Because of dramatic developments in nanotechnology, engineered UFPs for commercial and research purposes have been produced at a large scale. These incidentally and intentionally generated 25 UFPs are more harmful to human health than larger counterparts: UFPs have a higher chance to deposit in the lower respiratory system and are more toxic owing to their larger surface-to-volume ratios, which causes oxidative stress, pulmonary inflammation, and tumor development(Hext, 1994; Li et al., 2003; Renwick et al., 2004). Thus, onsite monitoring is needed to assess and minimize UFP exposure. High-precision industries with cleanrooms also need UFP monitoring to increase the production yield. For instance, in the semiconductor industry, the minimum linewidth of the chips is approaching 7 nm(Neisser 30 and Wurm, 2015). Particles that are a few nanometers in size are critical because "killer particles" (i.e., the diameter is greater than half of the minimum linewidth) can render the whole chip unusable(Libman et al., 2015). Unfortunately, since UFPs in cleanrooms are generated during fabrication processes (e.g., chemical vapor deposition (CVD), metallization, wet etching), contamination can occur in any manufacturing stages(Choi et al., 2015; Manodori and Benedetti, 2009). In these circumstances, a portable and low-cost sensor is needed for onsite UFP monitoring to accurately evaluate adverse health effects and control 35 the contamination level in cleanrooms to enhance the production yield. Condensation particle counters (CPCs) are one of the most widely used UFP detection instruments and are based on the heterogeneous particle condensation technique(Stolzenburg and McMurry, 1991). They grow UFPs to micro-sized droplets through condensation and count them by optical means. Compared to other detection techniques (e.g., electrical and