Air Sampling Instruments and Methods for Occupational Health
Pneumoconiosis
“Dust accumulation in the lungs and tissue reactions in the presence of this dust.”
There are two different types of pneumoconiosis:
- Collagen: Reactions with production of fibrous tissue and permanent alterations or destruction of alveolar structure caused by a fibrogenic dust (silica, asbestos) or a reaction to a non-fibrogenic dust (coal mineral production massive fibrosis).
- No Tissues: Those in which reaction occurs with reticulin and the honeycomb structure remains intact. This reaction may be reversible, such as pneumoconiosis are radiopaque metals (iron, tin, barium).
Silicosis
Disease caused by free silica (SiO2) and is characterized by disseminated nodular fibrosis is diagnosed by radiological examination and functional impairment has ventilator.
Agents: Free crystalline silica or silicon dioxide (SiO2). Not to be confused the total silica in which silicon is linked to other elements as silicates.
Compounds: Free silica occurs in different allotropic forms, which determine the pathogenicity of the compound:
- Crystalline: Quartz is the most common, tridymite and cristobalite
- Cryptocrystalline: Chalcedony (Agate), opal, Tripoli and flint
- Amorphous (noncrystalline), diatomaceous earth or kieselguhr.
Sources of exposure: The different forms of SiO2 are contained in the rocks (granite), pure quartz. Extraction, grinding, chipping of operations and use different means by dust:
- Mining: Drilling, mining, transport, crushing and grinding of metal ores (copper, iron), and non-metal (salt, coal)
- Mining: Mining and industrialization (grinding and sieving) Quartz
- Mining: Mining and industrialization (milling and sieving) of calcite for cement manufacture.
- Lab: Analysis of mineral samples
Air Sampling Instruments
The Health and Safety professional is interested in knowing what are the pollutants to which the worker is exposed, as well as its concentration in the air.
Accuracy required, complexity of the method, COST OF INSTRUMENT
Gases and Vapors
Gases and vapors can be evaluated using indicator tubes and allowing direct readings for laboratory evaluation can be collected in containers with a liquid absorbent or absorbed on appropriate solid (eg coal). For the detection of organic vapor is the standard method on activated carbon absorption followed by chromatographic determination. The gases and vapors that are insoluble in water but are soluble or react with other agents may be absorbed in a suitable solvent
Direct Sampling Instant
It is called direct sampling or instant collection and the air sample over a short time, usually between one and five minutes.
This method is ideal to follow the different phases of a cyclical process and to determine the maximum levels of concentration in the air, but this procedure requires very sensitive analytical methods because the amount of material to be analyzed can be very small.
Integrated Sampling
Integrated sampling is used when the requirements of sensitivity of the method of analysis make it necessary for sampling is performed during a defined period minimum (10 – 30 minutes) or when to set the compatibility or incompatibility for 8 hours.
This includes passing a known volume of air through an absorbing solution, liquid that captures and retains gaseous contaminants suspected. Therefore the mean sorbent is sent to a lab for further analysis. The integrated sampling method needs a reliable device to move air. however for prolonged periods of sampling the most practical source is an electric pump or fan These come in various types and sizes and should be chosen according to the sampling devices employed.
Qualifications of the Air
Color variations (loudness or pitch) are useful for degrees of air. a method for analyzing the composition of a solution by adding known amounts of standard solution until a reaction occurs and can be given a color change, precipitation or variation of conductivity) For example, you can put a glass bubbler a known concentration of a liquid reagent and a suitable indicator and pass a current of air at a constant rate until there is a perceptible change in color that matches the tone of the selected pattern. Under controlled sampling of the pollutant concentration in air is inversely proportional to the time needed to produce color variation.
Representative of Air Samples
To select the appropriate sampling method before doing the air test work area, you must know very well the nature of the pollutant in question and any problem substance that may be present in the atmosphere. To set the time-weighted average exposure and to relate it to the permissible exposure level (PEL) there must be an adequate number of test. In general the changes are less pronounced concentration of gases or vapors, particulate substances should not be discounted the importance of sampling site location, timing and number of samples to be taken during the course of an investigation of the environment work. When handling highly hazardous materials in bulk is advisable to perform continuous monitoring of atmospheric levels of the same. The sampling points should be located on jobs. To obtain a useful estimate of the dose of the toxic substance inhaled by the worker can be combined sites and the frequency of sampling with a time study of the worker’s activity.
However, exposure can also occur by routes other than inhalation, therefore, to make a fuller assessment of the exposure may be necessary to perform analysis of expired air, blood or urine.
These data should be combined with the knowledge gained by the physician in charge of the clinical course. All this is intended to emphasize the importance of occupational health programs.
Measurement
The regulations relating to worker exposure and among all health checks are preferably directed to the worker’s breathing zone.
SAMPLES OF THE BREATHING ZONE
The sampling of the breathing zone may require a series of several samples, ie samples every hour for a period or may involve one or two samples extended to cover the day. To calculate the weighted average exposure time is necessary to have an integrated personal sampling throughout the shift. Many of the permissible limits are based on time weighted average concentrations of air pollutants.
AREA SAMPLES
The area samples are used to establish the preliminary work on what should be sampled. They can also be used to determine whether the area should be isolated and restricted to prevent the influx of a highly contaminated area.
METHODS FOR THE COLLECTION OF SAMPLES
Various instruments used to collect gaseous substances in bottles, plastic bags or tubes containing activated charcoal, silica gel or other absorbent which reacts with the gaseous substance on hold.
Industrial hygienists use at times other devices to collect air samples as sampling devices for high-volume, precipitators voters, or cascade impactors for particle impactors. To calculate the absolute quantity of the substance listed should be corrected as the sample obtained for air temperature and normal pressure. This is essential to know the fundamental laws of gases and their application.
Bubbles
There are several types of bubblers glass or plastic that can be used as a device for indirect sampling. They contain water or other liquid to capture gaseous when air is passed through them.
Essentially consist of a sampling bottle containing a fixed amount of a liquid absorbent and a bubbler. As the air is passed through the bubbler, the contaminant is retained in the liquid.
Carbon tubes
Coal has retained ownership of (physically) gaseous substances on its surface. The sampling apparatus used coal as a means adsorbent consisting of small glass tubes with two sections of charcoal separated and retained by two glass fiber plugs.
For the sample of air, break the closed ends of the tube and slowly passed through the carbon air through a personal sampling device. After the sample was taken reseal the tubes and sent to the laboratory for analysis.