Repeated exposure to vapours, fumes and dust is a health hazard. Although vapours are invisible, and many dust particles can be very small (less than five microns) and also invisible to the naked eye, this doesn’t mean the dangers for operators don’t exist.
Broadly speaking, dust can be classified into two types: inhalable and respirable dust. Respirable dust particles are generally more hazardous, as they are small enough to get right into the smaller tubules of the lungs, and can cause physical blockage or irritation. It can extremely dangerous if the material is toxic or even carcinogenic, as the lungs may be able to absorb it quickly into the bloodstream.
Left unchecked, exposure to dust can lead to occupational asthma. This can be a serious condition leading to severe chronic asthma if exposure to a respiratory sensitiser continues.
How can you protect yourself from hazardous fumes and dust at work?
In the first instance, there may be ways to reduce the volume of fumes or dust that is made - or to ensure that less of it becomes airborne. In addition, you can reduce the hazard level if you are able to switch materials to an alternative that is less toxic.
One of the most common ways in which you can control fumes and dust is to extract it from the environment using a Local Exhaust Ventilation system (LEV)
which uses either filters or a duct to atmosphere system.
Removing fumes and dusts from the environment
The vast majority of LEV systems are ‘recirc’ or re-circulation extractors. Re-circulation extractors are devices that pass air through a filter to trap the fumes and dust and pass the clean air back into the local environment near the source.
The other main type of extraction system is known as a 'vented to atmosphere' system, but these are mainly targeted at hazardous fume extraction rather than dusts, unless a degree of filtration is present first. These are more traditional and involve a combination of ductwork, extraction hoods, and filters connected to a fan in the wall or roof and an exhaust that releases air outside the building or to an area away from the initial source.
For particulates (dusts and smoke) the most effective and probably the most widely known filtration system is a high efficiency particulate arrestor (HEPA). These filters are very fine and often remove higher than 99.99% of particles down to 0.3 microns.
Vapours or odours will pass right through a particle filter (even HEPA filters), so carbon filters are often used to adsorb these vapours. Not all carbons are suitable for every type of vapour however so the type of fume has to be matched to the right type of carbon. Activated carbon is the universal adsorbent and will filter "some of almost any vapour". Gases that are removed by activated carbon filter systems include organic compounds; chlorinated hydrocarbons; inorganic compounds, and odours. Special carbon additives can be mixed with activated carbon to make it more effective at removing certain types of chemicals.