Dust at Work and What It Does to Your Lungs
An occupational doctor explains respirable dust, silica limits, the diseases that follow years later, and the controls and health checks that prevent them.
See a doctor promptly if
- Breathlessness on exertion that is worse than it was a year ago, or a cough lasting more than three weeks
- Wheeze, chest tightness or cough that eases on days off and comes back at work. That is the classic pattern of occupational asthma
- Coughing blood, unexplained weight loss, or fever and night sweats in anyone with a silica history. That needs prompt assessment, including for tuberculosis
The short version
- The dust that harms you is mostly the dust you cannot see. Respirable particles under about 4 micrometers travel past the airways. They reach the gas-exchange region of the lung.
- Respirable crystalline silica is the most dangerous common workplace dust. Work limits are 50 micrograms per cubic meter over 8 hours in some places. Others use 0.1 mg per cubic meter.
- Silicosis, occupational COPD and occupational asthma build up quietly over years. So health surveillance looks for the change before you notice symptoms.
Fine dust you cannot see is the dust that damages lungs. Particles below roughly 4 micrometers (µm) are called the respirable fraction. They slip past the nose and airways and settle in the alveoli. Those are the tiny air sacs where oxygen crosses into the blood. The body cannot clear them easily. The inflammation they set off leaves permanent scarring over years.
Coarse visible dust is mostly a nuisance and an irritant. The invisible fraction is the health hazard. That is why exposure is measured with sampling pumps, not judged by eye.
The exposures that matter most#
Respirable crystalline silica. It comes from concrete, stone, brick, sand, engineered worktops, foundry sand and abrasive blasting. One widely used permissible exposure limit is 50 µg/m³ (0.05 mg/m³) as an 8-hour average. Its action level is 25 µg/m³ (0.025 mg/m³). Another common workplace exposure limit is 0.1 mg/m³, which is 100 µg/m³. Both numbers are small. A few minutes of dry cutting can blow past them for the whole shift.
Wood dust, above all hardwood. It is classed as a human carcinogen, which means it can cause cancer in people. It is linked to nasal cancer as well as asthma.
Flour and grain dust, one of the commonest causes of occupational asthma.
Welding fume, now classed as carcinogenic to humans. It causes metal fume fever and airway disease.
General inhalable and respirable nuisance dust. In some places it is capped as 8-hour averages. The limits are 10 mg/m³ (10,000 µg/m³) inhalable and 4 mg/m³ (4,000 µg/m³) respirable. Those are ceilings for otherwise low-toxicity dust. They are not targets to aim at.
What the diseases look like#
Silicosis and the other pneumoconioses, the dust scarring diseases, cause slowly worsening breathlessness and cough. They usually show up long after the exposure. No treatment reverses the scarring.
Occupational COPD accounts for a real share of all COPD, including in people who never smoked.
Occupational asthma is the one to catch early. If it is spotted and exposure stops within the first year of symptoms, many people recover a lot. If exposure carries on, the asthma often becomes permanent.
One pattern should always start a conversation. Symptoms ease on holiday, then return within a day or two of going back.
Controls that actually reduce exposure#
The order matters, and personal protective equipment comes last.
- Eliminate or substitute. Buy pre-cut material. Use a less hazardous abrasive than silica sand.
- Engineering controls. These cut the dust at source:
- On-tool extraction
- Water suppression for cutting and grinding
- Enclosure of the process
- Local exhaust ventilation, well designed and tested at least once a year
- Administrative controls. These limit who breathes it:
- Restrict who is in the dusty area
- Schedule dusty work when fewest people are present
- Use a vacuum with HEPA filtration rather than sweeping or compressed air
- Respiratory protection. Matched to the measured exposure, fit tested, and part of a written program.
Health surveillance, and why it is for you#
Where a real exposure exists, surveillance is a legal duty in most places. It means a baseline and repeat breathing questionnaire. It means spirometry, which is a breathing test. And it means chest imaging at set intervals for silica work.
It has two purposes. The first is to catch a falling trend in lung function while it is still small. The second is to prove what your lungs were like when you started. Ask for your numbers each time, and keep them.
Where to take this next#
Dust and noise are the two exposures where the damage is silent, builds up, and is completely preventable. Both rely on the same discipline of measurement, control and surveillance. The full guide to hearing loss and noise at work sets out how that discipline works in practice.
Test your breath-hold right here
Sit down. Take a deep breath in, press Start, and press Stop when you must breathe.
If you are buying a pulse oximeter
A fingertip oximeter under $30 is accurate enough for home use. Warm hands, sit still, and read the number after 30 seconds, not the first flicker.
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A question about your own situation?
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Common questions
If I cannot see dust in the air, am I safe?
How long does silicosis take to develop?
Does smoking make occupational dust worse?
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