Respirable dust, sampling

Air Samples Respirable dust samples are analyzed for quartz and cristobalite by x-ray diffraction (XRD). XRD is the preferred analytical method due to its sensitivity. 

Gravimetric, The only instrument for carrying out microscopy or personal respirable dust sampling, chemical... 

Using the background information summarized above, a procedure was developed in which the respirable dust samples were ashed, taken up in a suspension and redeposited on a membrane filter. The redeposited membrane filter was used to present the sample to the MIR cyrstal. The cyclone sampler used for collecting respirable dust selectively collects particles less than 10 microns in diameter and no effect was made to grind the particles as no problem in damaging the crystal was encountered. 

Johnson, D. L., and Esmen, N. A. (2004). Method-induced misclassification for a respirable dust sampled using ISO/ACGIH/CEN criteria. Ann Occup Hyg 48, 13-20. 

When determining mass concentration, total particulates can be determined or some pre-separation of larger particle sizes can be accomplished prior to filter collection. For respirable dust sampling a device such as a cyclone or... 

Respirable dust sample A sample collected with an approved coal mine dust sampler unit attached to a miner, or so positioned as to measure the concentration of respirable dust to which the miner is exposed, and operated continuously over an entire work shift of such miner. 

In view of the preceding, the measurement of dust exposure in many cases needs to be limited to that fraction of inhaled particles that are small enough to be deposited in the alveolar spaces. Thus, a size-selective air-sampling method is required to separate the respirable fraction from the coarser material that is deposited in the upper respiratory tract. The size selector most commonly used in respirable dust sampling has the following characteristics ... 

Respirable dust samples ate collected on a low ash PVC filter using a 10mm nylon cyclone at a flow rate of 1.7 1pm. 

A respirable dust PEL has not been established for noncoal mines, but a nuisance dust standard of 10 mg/vnf is regulated. The nuisance dust sample is comprised of total dust, which represents airborne particles that are not selectively collected with regard to their size. However, respirable dust sampling is conducted in non-coal mines if potential exposure to silica dust is suspected. If the siUca content of the respirable dust sample exceeds 1%, the formula used to establish the dust PEL is 10 divided by (the percentage of siHca + 2). Thus, a sample with 8 pet silica would have a dust PEL of 1 mg/m. ... 

Approximate Values in Units of Percent The particle size distribution in a total dust sample is unknown and error in the XRD analysis may be greater than for respirable samples. Therefore, for total dust samples, an approximate result is given. (4) Nondetected A sample reported as nondetected indicates that the quantity of quartz (or cristobalite) present in the sample is not greater than the... 

Wesley and Wall (4 ) and Brown and coworkers (18) collected dust samples at five cotton gins with high volume air samplers at three locations in the gin. The dust was removed from the filters in the seime manner as the weave room dusts discussed above. The average ash content was 32.9%. X-ray fluorescence analyses showed that silicon was the most abundant element detected (7.69%), followed by potassium (1.82%), aluminum (1.46%), calcium (1.15%), magnesium (1.05%), phosphorous (0.52%), iron (0.45%), sulphur (0.33%) and chlorine (0.16%). The total dust was separated into a "respirable fraction" (28) by the sonic sifting procedure and analyzed as above. The ash content of the respirable fraction of gin dusts increased to 46.0%. Only the... 

Air Volume NaDCC Respirable Dust NaDCC Total Dust Sample Number Job Classification Liters mg/Filter mg/m3 mg/Filter mg/m3... 

Sample Number Job Classifi- cation Air Volume Liters TCCA Respirable Dust mg/Filter mg/m3 TCCA Total Dust mg/Filter mq/m3 ... 

Previous work has shown that the 3.3-5.5 /xm coal fraction has a particle size distribution similar to that of respirable mine dust collected on personal samplers during mining operations (13). This fraction was used for the spark-source analyses. The coals used in this investigation are identified in Table I. The respirable dusts were obtained from personal sampler filters submitted to the Dust Group, Pittsburgh Technical Support Center, Federal Bureau of Mines. The samples were collected during actual mining operations. 

This investigation has shown that for the majority of the 10 pairs of dust samples investigated, nine elements including Ag, Cd, Cu, Zr, Rb, Ca, Cl, P, and Br show much higher concentrations in the mine dusts collected during mining operation than in the corresponding respirable-... 

Pollution of the atmosphere is a frequent cause of trouble thus in 1929 the cattle dipping truck yards at Julia Creek, Queensland, were removed owing to contamination of the town atmosphere, dust samples from which disclosed 10 to 12 parts of arsenic per million.3 Chronic poisoning has also resulted from the inhalation of the fumes liberated on burning mosquito incense made from orpiment and sawdust.4 A systematic clinical and X-ray examination of furnace workers at the arsenic works at Freiberg, Saxony, revealed that the majority suffered from pustular and eczematous conditions of the skin and 80 per cent, showed ulceration and perforation of the septum of the nose, in spite of the provision of sponge respirators and protective clothing 5 arsenic was present in the hair and nails. 

In Figure 2, the infrared absorbance spectrum of a redeposited blank filter, a, is compared directly with that of a redeposited field sample filter, b, which has a calculated 59 micrograras of quartz on it. The original filter from a foundry had 0.222 milligrams of respirable dust on it. Figure 3 is the infrared absorb-... 

The amount of particulate collected on the filter is determined by weighing the filter under the same physical conditions as prior to sampling. The amount of particulate with respect to total sampling time and flow rate determines the dust concentration in milligrams per cubic meter (mg/M ). The current OSHA Threshold Limit Value for nuisance or inert respirable dust is 5 mg/M. ... 

With mass respirable sampling, an attempt is made to separate the aerosol into two fractions representing the mass that would be deposited in the alveolar region and the mass that would not be deposited in this region. To do this, it is necessary to define the size distribution of particles deposited in the alveolar region. This material is defined as respirable dust. 

Respirable coal mine dust samples from three different US mines were classified into four fractions using a Bahco classifier [34]. Shape factors were determined as ratios of the following mean diameters. From microscopy ... 

The method by Wells and Alexander uses lower air velocities (the extraction rate is only 50 litres/minute) and does not, therefore, require a deflector plate. The method does not necessarily release all of the potentially airborne particles in the sample in fact, the dust release may be constant in many repeated pourings of the same sample. Either total airborne dust samples may be collected on a filter (i.e. all particles that are still airborne on leaving the box, i.e. smaller than about 10 microns) or only the respirable fraction may be collected by extraction through the Hexhlet sampler. 

The selective sampling of respirable dust. Inhaled particles and vapors (C. N. Davies, ed.), pp. 465-475, Pergamon Press, Oxford (1961). 

While AIHA supports lowering existing concentration limits for respirable coal mine dust, the organization objects to MSHA s bid to expand the requirements of certified persons who perform dust sampling and who maintain and calibrate sampling equipment, said AIHA President Michael T. Brandt, DrPH, CIH, PMP, in a written statement. Linder the proposal, individuals must be certified by passing an MSHA examination to demonstrate competency in respirable coal mine dust after completing an MSHA course of instruction. 

Dust Sampling, respirable dust (q.v.) concentrations are routinely measured in the workplace. Measurements may be taken over a long period in the general environment (see gravimpinger) or by personal dust samples such as the Casella, carried by the operative. Dust samples collect specimens in filters, and the collected samples are weighed and analysed, (see threshold limit value). The methods for sampling are specified in the UK by MDHS 14,1993 (q.v.) and in the USA by NIOSH (q.v.) Manual of Analytical Methods, DHEW Pub. No. 84-100, revised 1987. The dust is collected on special filters (see below), and weighed and analysed. 

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