Risks in Abrasive Blasting and Shot Blasting

Abrasive blasting safety: which method, which risk?

Abrasive blasting is a surface preparation process in which abrasive particles are propelled onto a surface by compressed air or a rotating turbine to remove layers such as rust, paint, moulding sand or burrs. It is widely used in metal and machinery manufacturing, casting cleaning, steel structures and tank maintenance. From the point of view of abrasive blasting safety, there are major differences between methods:

Glove box cabinet: The part is inside an enclosed box, and the operator works from outside through glove ports. The operator is outside the abrasive stream.
Blast room: The operator works inside a ventilated room with large parts, holding the nozzle by hand.
Open blasting: Carried out on site, on bridges, tanks or steel structures, under conditions with limited separation from the surroundings.
Shot blasting machines: Rotating turbines throw steel shot at the part; the operator is outside the machine, and the risk arises mostly during maintenance and breakdowns.

Three risks are common to every method: dust from the abrasive and the coating removed, high noise, and compressed air. In this article we deal in turn with the measures to apply on site for each.

Choosing the abrasive: where the dust risk begins

The decision that reduces dust risk the most is which abrasive is used. Art. 5 of Law No. 6331 lists replacing the dangerous with the non-dangerous or less dangerous among the principles of prevention. When choosing an abrasive, you can use the following table as a starting point:

Abrasive	Key feature	Point to watch
Silica (quartz) sand	Cheap and easy to find	Produces respirable crystalline silica dust when it breaks down; the first abrasive that should be substituted
Steel shot and steel grit	Reusable, produces little dust	Dust from removed paint and rust still forms; risk of ejection in shot blasting machines
Aluminium oxide (corundum)	Hard, cleans quickly	Dust generation can be high; dust collection essential
Garnet	Low dust, good finish	Check the free crystalline silica content in the safety data sheet
Glass beads	For delicate surfaces	Broken beads produce dust; local exhaust needed
Slag-based abrasives	Cheap, single use	Check the heavy metal content in the safety data sheet

As important as the abrasive itself is the coating being removed. Old steel structures and machinery may have paints containing lead or chromium; in this case, dust measurement and health surveillance must also cover these agents. For the assessment of chemical agents, see our article on chemical risk assessment.

Is silica banned in blasting?

The text of the Regulation on Dust Control contains no provision that bans silica sand by name for blasting metal surfaces. However, this does not mean its use is unrestricted and safe: silicosis is on the list of occupational diseases, and abrasive blasting is explicitly listed among the jobs with a risk of the disease. Taking the Law's substitution principle and dust control obligations together, switching to a silica-free abrasive should be the default decision. If silica sand continues to be used, the justification, the measures taken and the measurement results must be written clearly in the risk assessment. We explain the health effects of silica in our article on crystalline silica dust.

Blasting cabinets, blast rooms and shot blasting machines

Enclosed systems contain dust at source, but only when they work properly:

Negative pressure inside cabinets and rooms: While the dust collector is running, the inside of the cabinet must be under a slight vacuum relative to the outside, and dust must not leak out through the door and glove ports. Glove tears and door seals are checked at the start of every shift.
Door interlock: When the door of the blast room or shot blasting machine is opened, the abrasive flow and turbine must stop. A machine with its interlock bypassed is a non-conformity frequently found on site.
Dust collector: Changing filters and emptying dust are the tasks with the highest dust exposure; they are done with suitable respiratory protection and without raising dust. Systems that collect combustible metal dusts such as aluminium also carry an explosion risk; details are in our article on dust explosion risk.
Maintenance of shot blasting machines: Maintenance of the turbine, elevator and screw conveyor is always carried out after the energy has been isolated and locked; the steps are in our article on the LOTO procedure. Running the machine "as a test" with the turbine cover open is a typical cause of shot being ejected.
Cleaning: Cleaning is not done by blowing with compressed air; spilled abrasive and dust are collected with an industrial vacuum.

In open blasting, employees and neighbouring work in the surroundings are also affected. The blasting area is enclosed with tarpaulin or temporary screens, entry is open only to employees with protective equipment, and work is carried out taking wind direction into account.

Blasting helmet: air-fed hood

For the operator holding the nozzle in a blast room or in open blasting, a dust mask is not enough; the operator's face is directly exposed to abrasive rebound and a dense dust cloud. In this work, an air-fed blasting helmet is used. The helmet supplies the operator with breathable air from a separate line; its visor and the cape that falls over the shoulders protect against abrasive rebound.

Whether the helmet provides protection depends on the incoming air being clean:

Breathing air must comply with a standard such as EN 12021, which defines compressed air quality for breathing apparatus.
The compressor's air intake must open to clean air, away from vehicle exhausts, forklift fumes and blasting dust.
In oil-lubricated compressors, overheating can produce carbon monoxide; fitting a filter and a carbon monoxide alarm on the air line should be considered.
The visor lens and protective film are replaced regularly; a scratched visor impairs vision and pushes the operator to lift the helmet.

Helpers in the blasting area use respiratory protection suited to the dust level and eye protection; for mask selection, see our article on dust masks FFP1, FFP2, FFP3. Maintenance records for the helmet and air line should be kept together with personal protective equipment issue records.

Compressed air, hose and nozzle

The blasting hose carries abrasive at high pressure. When the hose or coupling breaks, the freed hose whips around like a lash, the nozzle is out of control and the abrasive stream is directed at everyone nearby. The measures are:

Deadman control: The nozzle must be fitted with a remotely controlled valve that stops the flow when the operator releases the trigger. Taping the control lever down removes this protection.
Coupling safety: Hose connections are secured with safety pins or locks; whip check cables are used against breakage.
Hose checks: Worn, crushed or swollen hoses are not used. The hose route does not cross vehicle routes.
Static electricity: The abrasive flow builds up static charge in the hose and nozzle; the operator feels electric shocks and a spark risk arises in flammable atmospheres. For antistatic hoses and earthing, see our article on static electricity and earthing.
Pressure vessels: Compressor tanks undergo periodic inspection at least once a year under Annex III of the Work Equipment Regulation. Determine with an authorised person under which scope your blasting pot will be inspected; details are in our article on pressure vessels and compressor tanks.

Noise, vibration and health surveillance

Blasting nozzles and shot blasting machines often produce sound above the upper exposure action value in the noise regulation. Under the Noise Regulation, hearing protectors are made available at the lower action value of 80 dB(A), their use is mandatory at the upper action value of 85 dB(A), and the limit value of 87 dB(A) must not be exceeded even when the protector's effect is taken into account. For hearing protectors to be used under a blasting helmet, a type compatible with the helmet must be chosen. We explain the values in our article on the noise regulation. Holding the nozzle for long periods can also lead to hand-arm vibration; see our article on the vibration regulation.

We plan dust and noise measurements with accredited laboratories and enter the results into the risk assessment. In health surveillance, the workplace physician:

Orders chest X-rays to ILO standards for dusty work and determines their frequency.
Orders hearing tests if the upper action value of 85 dB(A) is exceeded.
Requests lung function tests if considered necessary; the legislation sets no fixed frequency for this test, and the physician decides according to the risk.
Adds the relevant tests if the coating being removed contains agents such as lead.

We plan tests with authorised laboratories and health institutions. At Bursa Sistemer, we inspect blasting areas on site in metal and machinery businesses as part of our OHS specialist service and track measurement and examination dates through the OHS calendar.

Frequently Asked Questions

Is a dust mask enough for someone working at a blasting cabinet?

In a glove box cabinet, the operator is outside the abrasive stream, so if the cabinet is sound and the dust collector is working, additional respiratory protection is usually not needed; however, a dust mask is used when changing filters and cleaning the cabinet. In blast rooms and open blasting, an air-fed blasting helmet is required.

Is blasting with silica sand banned?

The text of the Regulation on Dust Control contains no provision banning silica sand by name for blasting metal surfaces. However, because of the silicosis risk and the Law's substitution principle, a switch to a silica-free abrasive is needed, and if use continues, the justification must be written in the risk assessment.

Is a shot blasting machine subject to periodic inspection?

The compressor tank, electrical installation and earthing connected to the machine are inspected annually under Annex III. Determine with an authorised person, together with the manufacturer's instructions and the risk assessment, what inspection will be carried out on the machine itself.

What is done in the health surveillance of an employee who carries out blasting?

For dusty work, the workplace physician orders chest X-rays to ILO standards, and hearing tests if the upper noise action value is exceeded. The physician determines the frequency of X-rays and other tests according to exposure.