Two types of hazard are associated with dust and fumes: those that are easily anticipated and those that are rather more obscure but nonetheless hazardous. Unfortunately, the list of dangers we didn't anticipate shows no sign of getting shorter. We continue to be surprised by dust explosions we thought were impossible and shocked by new science linking dust exposure to serious medical conditions.
In factories, homes, restaurants, shops, and offices, the precise constituents of dust and other airborne pollutants is rarely known. It makes sense to consider all dust as potentially combustible dust. The great Banbury custard explosion of 1981 is still often joked about - but nobody was killed. Unfortunately, other incidents have taken hundreds of lives. Dust can never be taken for granted. In November 2018, there was a major explosion in a cement silo in Martinsburgh, WV . Cement was previously thought so safe that it had been used as a fire and explosion suppressant. To add to the surprise, dust collection equipment has been blamed for causing it.
Unfortunately, dust has a natural tendency to collect where you don’t regularly look for it: on roof girders, above suspended ceilings, and inside industrial dust collection systems or air conditioning ducts that are not up to the job.
If fire and explosion hazards are hard to predict, what about the health implications of everyday dusts and fumes?
Health and safety guidelines and media coverage have alerted us all to the dangers of carbon monoxide, asbestos, and (hopefully) volatile organics (VOCs). Most of us know that refrigerator gases are bad for the ozone layer and we believe that carbon dioxide is bad for the weather. We’ve probably heard that the soot in diesel exhausts causes asthma and we don’t put lead in petrol. Unfortunately, that probably sums up the level of knowledge for most people with regard to the medical and environmental hazards of dust and fumes. We are dangerously complacent.
The most dangerous types of dust are the ones you often can’t see. Particles between 0.01 to 100 microns in size are “inhalable,” but those below 10 microns are “respirable.” Respirable particulates penetrate deep into the lungs, enter the circulation, and contribute to strokes, heart disease, lung cancer, COPD, respiratory infections, asthma and neurodegenerative diseases. Airborne particles have been shown to correlate with low birth weight in babies and premature labor . They have been identified in human placentas and human brains, with strong evidence of effects on intelligence .
There are many good reasons to install the best air quality control you can afford, but here are some airborne dangers many are unaware of.
Government estimates are that over 500 construction workers die every year because of the effects of ordinary windblown dust (silica) . When you realize that workers in the construction industry spend most of their time in the “fresh air” it underlines just how hazardous our building construction materials really are. Construction dust causes lung cancer, asthma, chronic obstructive pulmonary disease (COPD), and silicosis.
When construction workers were asked what importance, they think their industry puts on dust control, 44% answered ‘very little,’ only 12.5% thought it was a priority, and only 3% were fully aware of the risks .
Even though it is now in most domestic and commercial lofts, there are still some questions around the safety of Glass Reinforced Plastics (GRP), more commonly known as fiberglass. Some experts feel that that not enough research has been done into the effects of long-term exposure.
Toner and Printer Ink
Surely you’re safe in the office? If you use photocopiers and printers heavily, maybe not. A whole host of health risks have been associated with toner ink. Carbon black has been classified by the International Agency for Research on Cancer as a 2B carcinogen, and the London Hazards Centre has expressed concern that photocopiers generate significant quantities of carbon monoxide and ozone when they get hot from heavy use . They also emit volatile organics .
As long ago as the 1950s, exposure to coffee dust had been associated with respiratory problems such as asthma and other changes in the lung. In 1996, The HSE published a conclusion that “There is sufficient evidence to conclude that coffee bean dust meets the revised EU criteria (1996) for classification as a respiratory sensitizer (a cause of asthma) and labelling with R42.” 
Allergies continue on their upward trend in the UK, along with some types of auto-immune disease. A diverse range of materials and chemicals are now believed to be “sensitizers.” Fairly minor exposures can lead to a lifetime of immune system overreaction, manifesting as skin rashes, respiratory diseases, and malaise. Common manufacturing ingredients like toluene, diisocyanate (TDI), and formaldehyde are major causes, and they are constantly being released from synthetic carpets, curtains, and furniture. Plain wood dust is also a major sensitizer.
In addition to toxic metals, soldering involves “flux.” Flux is a resinous side-product from the distillation of turpentine. Also known as colophony, it consists mostly of abietic acid with smaller quantities of stilbene derivatives, amine hydrochloride activators, and other hydrocarbons. When heated, the side products include hydrochloric acid, benzene, toluene, styrene, phenol, chlorophenol, isopropyl alcohol, and aliphatic aldehydes.
Twenty percent of employees who work with or near soldering (electronics assembly, refrigerator engineers) develop asthma, and studies show it’s the main cause of illness and employee turnover in those industries. Metals also become airborne during soldering. Exposure to lead and other heavy metals can result in sterility, abortion, brain damage, fatigue, irritation, and anemia .
This is another fibrous material with similarities to fiberglass and asbestos. It easily becomes an airborne dust when cutting, milling or finishing, and tends to stick to surfaces, including human skin and mucous membranes. The main risks derive from solvents used in its production and from the resinous epoxy coatings applied to the fibers. Known problems include eye irritation and visual disturbances, respiratory effects, dizziness, drowsiness, nausea, dermatitis, and sometimes vomiting .
Again, every home and office has it, but there is a reason they don’t like plaster and plasterboard at waste disposal sites. It tends to emit toxic gases including hydrogen sulfide and other sulfurous fumes. Lime, sulphate hemihydrates, silica, and mica readily become airborne and cause respiratory complaints such as asthma, COPD, chronic bronchitis, and irreversible emphysema .
The dust in almost every modern building contains cement derived from concrete, mortar, tiles, and other products. Cement dust is known to cause lung impairment, COPD, pneumoconiosis, and lung cancer. Like sand, it can break down into very small particles and penetrate deep into the body reaching every organ, including the heart, liver, kidneys, spleen, bones, and muscles. It can cause stomach and colon cancer and arthritis. It has even been discovered growing inside our hair .
Amorphous silica forms fine airborne particles more readily than the crystalline silica in sand or cement. It is present in a vast range of modern products including rubber, silicone, car tires, as an anti-caking agent in all kinds of other powdered materials, as a liquid carrier for animal feed and agrochemicals, in toothpaste and cosmetics, paint, insulation materials, adhesives, coatings, and printer ink .
The risks of this “green” product begin long before it is burned to generate electricity in power stations or onsite generators. There is no precise definition of biomass and in some cases, the product includes sewage sludge, hazardous wood waste such as particleboard, and high levels of heavy metals. Biomass dust and fumes contain bacteria, fungi, molds (including penicillium and aspergillus), actinomycetes, endotoxins, aldehydes, monoterpenes, and resin acids. It also gives off carbon monoxide that has caused deaths during storage and transportation. Biomass ash contains cadmium, chromium, lead, nickel, manganese, and aluminum.
Similar hazards are familiar from agricultural industries that handle hay, straw, potatoes, and many other stored products. Biomass dusts cause eye, nose, and respiratory irritation (including “farmer’s lung”), alveolitis, and granulomatous disease .
What could be safer than natural wood? However, lung cancer was first discovered because of health problems observed in saw mills. Wood dust is also linked to Hodgkin’s disease, leukemia, gastrointestinal cancer, tremors, chronic fatigue syndrome, kidney failure, toxic pneumonitis, hypersensitivity pneumonitis, and to a variety of allergies and immune diseases.
Dust in nail bars, chiropodists, and podiatry clinics often contains keratin, keratin hydrolysates, microbial debris, and fungi (dermatophytes and saprotrophs). Workers are four times more likely to suffer from asthma than the national average. The dust may also expose them to contagious diseases such as hepatitis B and C or HIV.
Nail bars and beauty salons are also hazardous environments because of the chemicals in hair treatments and nail varnish.
A common activity in any workshop is tool sharpening. However, saw blades and other sharp edges usually contain cobalt as a binder for tungsten carbide and even a small amount can be harmful. It has been linked to interstitial fibrosis, interstitial pneumonitis, myocardial and thyroid disorders, asthma, interstitial lung disease, skin allergies, and hyperplasia of the bone marrow .
Almost all high-speed grinding, sharpening, milling, and drilling tools and welding operations propel a complex soup of chemicals into the air causing “fume fever.” The sickness is just as common when your material is a polymer rather than a metal.
Fiberboards such as MDF were embraced on a massive scale in the 1990s and are still heavily used today. These synthetic woods are essentially fibrous scrap bonded with a carcinogenic formaldehyde based resin. Unfortunately, MDF and other fiberboards produce more dust than true timber when cut or sanded and the particles are small and “respirable.” At a TUC conference, deputy general secretary of Bectu, Roy Lockett, said, “MDF is the asbestos of the nineties. It is carcinogenic. It causes lesions. It damages the eyes, the skin, the lungs, and the heart. It is vile and pernicious.”
Independent advisory service, London Hazards, has also drawn attention to the fact that home and office furniture made from MDF continues to slowly emit formaldehyde, causing asthma, allergies, and cancer. Any office with furniture built from MDF needs good ventilation .
Finding Safe Solutions
If you’re concerned about a dust or fume hazard, the first question to ask is whether you need to create it. Often there are safer materials you could substitute, alternative methods that won’t make pollutants airborne, or automation to keep workers at a safer distance.
Another question to ask about your dust suppression strategy is whether it adds to the risks. Cheap solutions that collect polluted air from one location and deposit it in another are often worse than useless. While an individual welder might appreciate a fan that blows dust and fumes away from his face, those pollutants will now contaminate the environment over a much wider area. Leaky ducts have been known to deposit the dust they collect into the ceiling voids. From there it either slowly or suddenly tumbles back into the air. Underpowered or underserviced ducts may accumulate debris and become fire or toxic hazards in their own right.
The ideal extraction system fulfils all the following objectives: it must safely process or convey away the hazard; its components must not contain potential sources of ignition (so use non-sparking fans, spark arrestors, and pre-separators); it must be as quiet and unobtrusive as possible; and it must be inexpensive to operate.
Today’s professionally installed dust extraction technology can fulfil all of these criteria.
The most common way to extract airborne hazards is with a Local Exhaust Ventilation (LEV) system. This is an extractor that ducts the air away, through filters or direct to the environment. Dust extraction professionals will perform some very involved mathematics to ensure that the ducts, filters and compressors in industrial fume extraction systems will perform with the required air volumes and pressures.
If you haven’t looked into the costs and benefits of dust extractors in a while, you’ll have missed many improvements. Fan-blade redesigns and improved compressors enable modern systems to make a fraction of the noise of some older models, with more power and lower running costs.
Filter technologies include High Efficiency Particulate Arrestors (HEPA), F grade, or Eurovent filters, dust bag filters, course dust filters, M Class filters, inline dust filters, and activated carbon filters. New kinds of nanofibers are appearing that can collect greater quantities of dust before they need changing or replacing. There also systems that eliminate certain types of dust using static electricity, magnetism, or combustion.
When valves perform badly, filters and ducts clog with deposits. When valves and filters clog up, the building’s occupants often take a long time to notice and intervene, during which time they are unprotected. New types of valve (especially in pulsed systems) can significantly reduce maintenance overheads.
Significant economy and energy consumption improvements are attainable through real-time monitoring of air quality. Instead of constantly running, sensor-equipped systems can be relied on to switch themselves on, change intensity, or switch off completely without relying on human intervention or judgements of air safety.
Whether expelling or recirculating your air, it is often possible to combine air-quality control into an integrated HVAC solution that minimizes heat loss in cold weather, provides cooling in hot weather, or reclaims energy using a heat exchanger. Air cooling systems are far more energy efficient today thanks to new refrigerant gases. Twenty years ago, air conditioning systems consumed 6000 watts to cool an average house. Today that same job would likely consume just 1710 watts per hour.
Future Dust and Fume Extraction Regulations
With increasing numbers of serious human maladies being linked directly to the air quality in our workplaces, every business needs to sit up and take stock. In the first place, worker sickness, turnover, replacement, and training are huge overheads in their own right. In the second, new scientific findings will inevitably become a basis for future industrial liability litigation, rising insurance premiums, and tighter government controls.
There are tentative suggestions that industrially produced particulates could be making a significant contribution to global warming - by absorbing solar heat and imparting it to the troposphere . If so, stricter dust and fume extraction regulations will surely arrive sooner rather than later.
Paul Riddick is co-founder and technical director at Vodex (Southampton, UK), a fume and dust extraction specialist. For more information, call +44 (0)1489 899 070 or visit www.vodex.co.uk.
More articles on combustible dust:
 J. Marvin Herndon and Mark Whiteside in Journal of Geography, Environment and Earth Science International May 2019. See http://www.tanker-enemy.com/PDF/FEV.pdf