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Getex discuss different methods to measure dust and airborne particulates problem

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article image Solution for dust and airborne particulates problem from Getex

Increasing attention is being paid to dust and airborne particulates. This is because more and more studies are showing that long term exposure to very fine dust particles results in serious health damage. Getex provide solution for dust and airborne particulates problem.

Airborne dust and particulates are regulated in different ways by Environmental authorities and by Occupational Health and Safety regulatory authorities.

Typically the Environmental people set guidelines for total weight of dust in outdoor air based on the amount of dust, or of certain particle sizes, per unit volume of air measured on many occasions over a long period of time, with a maximum allowed value.

Occupational standards are set for the maximum 8 hour exposure to total dust, or to a smaller particle size fraction, per unit volume of air, measured on one occasion.

The methods of measurement are different. For outdoor air, large quantities are sampled by a high volume air sampler, which gives total weight of dust over a set period, TSP, or which can be modified to measure only smaller size particle fractions, for example, PM10 (particles 10 micros in diameter and less) or PM1 (particles 1 micron in diameter or less).

Another method of measuring the amount of dust in outdoor air is by a TEOM, Tapered Element Oscillating Microbalance. The TEOM is the only real time particulate monitor that directly and continuously measures the mass of particulates collected on a filter and provides continuous particulate concentration data.

An alternative method is the use of a laser reflectance device which can be set to datalog results and which can track amounts of various particle sizes. For special circumstances other devices are employed. Construction sites are often monitored by using dust deposit gauges. These are suitable for long term monitoring and are less expensive than the previously described methods.

Occupational exposure to dust is measured by sampling smaller volumes of air over an 8 hour period. The air is drawn through a conditioned preweighed filter using a constant volume sampling pump calibrated to a NATA accredited regime. The exposed filter is conditioned and reweighed. A finer size fraction can also be sampled. The result is calculated in mg/m3 of air and compared with an allowable exposure standard.

The sampling head can be set near the worker’s breathing zone, or the measurement be made statically by setting the pump in the general work area. If the occupational exposure differs from 8 hours a day over a five day week then the allowable amount of dust must be calculated. For example, exposure of 12 hours a day over a six day week, and with certain other assumptions made, would result in the allowable level being only a little over half that allowed for a 8 hour day 5 day week.

Again, there are other ways of measuring occupational exposure to dust, including laser reflectance meter readings of particles per cubic meter of air, and data logging of laser reflectance results. Increasing attention is being paid to the amount of ultrafine particles in the air. This is because these particles penetrate deep into the lung where they are not exhaled, and over time can have very major effects, even where the dust does not contain anything particularly toxic and is just general nuisance dust. Where the dust contains something more toxic, then the allowable amount of dust tends to depend on the amount of the toxic component, but may also be limited by the total amount of dust.

Common toxic components include silica, materials contained in wood dust, or lead from sanding old paint. Each of these toxics in dust has its own methods, guidelines and protocols. Airborne dust can collect nutrients and is a breeding ground for micro organisms including bacteria and viruses, especially where the relative humidity is high.

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