PAPR Respirators Explained – A guide for stone fabricators
Respiratory protection has become an increasingly important consideration for stone fabricators, particularly for cutting, grinding and polishing materials that contain crystalline silica.
The Health and Safety Executive (HSE) has published specific guidance for fabricators working with engineered stone, setting out measures to control exposure to respirable crystalline silica (RCS). These include using appropriate water suppression and other control measures alongside suitable respiratory protective equipment (RPE).
Powered Air Purifying Respirators (PAPRs) are one form of RPE that can be used to help protect stone fabricators from airborne contaminants such as silica. However, the varying specifications that come with PAPR respirators can make comparing them very difficult.
In this guide, we explain what many of these terms mean, how PAPRs work and some of the key decisions you’ll need to make when selecting respiratory protection for fabricating stone.
What is a PAPR respirator?
PAPR stands for Powered Air Purifying Respirator. It is a powered form of respiratory protective equipment that uses a motor fan to draw contaminated air through filters before supplying a constant flow of filtered air to the wearer.
Unlike a traditional disposable face mask, which relies on the wearer drawing air through the filter as they breathe, a PAPR uses battery power to maintain airflow. Depending on the system, filtered air is supplied to a hood, helmet, visor or tight-fitting facepiece.
This powered airflow can also make PAPRs more suitable for longer periods of use. HSE recommends considering powered RPE or breathing apparatus where RPE needs to be worn continuously for long periods; tight-fitting unpowered RPE should generally not be worn continuously for more than an hour. For most factories, the average shift is longer than one hour.
Why are PAPR respirators used in stone fabrication?
Cutting, grinding, drilling and polishing stone can generate significant amounts of dust.
Some stone materials, such as engineered stone, contain crystalline silica. RCS is the respirable fraction of dust that contains crystalline silica i.e. silica particles sufficiently small to penetrate deep into the lungs.
Exposure to RCS can result in serious health conditions including:
The level of risk depends on several factors, including the material being processed, the task being carried out, the duration of exposure and the how effective the control measures in place are.
PAPR respirators do not prevent silica dust from being generated, they prevent fabricators from inhaling the dust that is generated. RPE should be used alongside appropriate controls designed to minimise dust exposure at source.
What do TH2 and TH3 mean?
When comparing powered respirators for the stone industry, you may come across the classifications TH2 and TH3.
TH classifications apply to powered filtering respirators incorporating a hood or helmet under BS EN 12941. They indicate the performance of the complete respirator system, including the maximum permitted inward leakage.
TH2 systems have a maximum permitted inward leakage of 2%, while TH3 systems have a maximum permitted inward leakage of 0.2%. This means the permitted inward leakage for a TH3 system is ten times lower than for a TH2 system.
In the UK, TH2 powered hoods and helmets are assigned an APF of 20, while TH3 systems are assigned an APF of 40. The appropriate protection level should be determined by the workplace COSHH assessment and the type and concentration of contaminant present.
It is important to note that TH2 or TH3 classification alone does not determine which types of contaminants a PAPR can protect against. The correct filter must also be selected for the specific hazard.
What does APF stand for, and what does it mean?
APF stands for Assigned Protection Factor. It indicates the level of protection that correctly selected and used RPE is expected to provide.
For example, an APF of 20 means the respirator is expected to reduce the concentration of the hazardous substance inside the facepiece to one twentieth or less of the concentration outside. An APF of 40 provides a higher level of assigned protection, reducing the concentration to one fortieth or less.
Current HSE guidance for working with engineered stone specifies powered air-purifying respirators with an APF of at least 20 when processing the material, cleaning or maintaining machinery. The protection factor required for a particular workplace and task should be determined through an appropriate COSHH assessment.
For powered hoods and helmets classified under BS EN 12941, the UK Assigned Protection Factors are:
| PAPR Classification | UK APF |
| TH2 | APF 20 |
| TH3 | APF 40 |
Do PAPR respirators require face fit testing?
It depends on the type of PAPR.
Loose-fitting PAPR systems
Powered hoods, helmets and visors do not rely on a tight seal against the wearer’s face. Instead, they rely on a sufficient supply of clean, filtered air to prevent contaminated air leaking into the breathing zone. Because they do not rely on a face seal, these types of powered respirator do not require face-fit testing.
Loose-fitting PAPR systems can therefore be particularly practical where several employees require respiratory protection or where workers have facial hair, provided the selected system offers adequate protection for the hazard and task.
Tight-fitting PAPR systems
A tight-fitting respirator relies on achieving an effective seal against the wearer’s face.
Where RPE relies on this face seal, face-fit testing is required to confirm that the selected equipment provides an adequate fit for the individual wearer. Facial hair or stubble in the sealing area can prevent tight-fitting RPE from achieving an effective seal, which makes this type of respirator unsuitable for fabricators with facial hair.
It’s crucial to always check the manufacturer’s instructions and your workplace RPE assessment before investing in respiratory equipment.
Can you wear a PAPR with a beard?
Potentially, depending on the type of PAPR.
Tight-fitting respirators rely on achieving an effective seal against the wearer’s face. Beards or stubble within the sealing area can interfere with this seal, so tight-fitting RPE should not be used where facial hair prevents an adequate face seal.
Loose-fitting powered hoods and helmets do not rely on the same type of facial seal and can therefore provide an alternative for workers with facial hair, provided the system is suitable for the hazard, task and required level of protection.
What should you look for when choosing a PAPR?
Protection level
Check the PAPR classification and Assigned Protection Factor (APF). For powered hoods and helmets under BS EN 12941, TH2 and TH3 correspond to UK APFs of 20 and 40 respectively. Current HSE guidance specifies an APF of at least 20 for PAPR used when processing engineered stone, cleaning or maintaining machinery. A higher APF may be selected where the COSHH assessment identifies that a higher level of respiratory protection is required.
Battery life
Check that the battery life is enough for your shift. If the mask will be used for a full shift, ensure you choose a mask that will run the full length, and can be charged quickly. It is also a good idea to check you can purchase spare batteries for backup.
Airflow
Check whether you can adjust the intensity of the airflow and whether the mask gives warnings if airflow falls below the required level.
Comfort and weight
Respiratory protection only works when it is worn correctly and consistently. Check that the weight of the helmet or face mask, belt and battery isn’t too heavy. Also, make sure visibility, movement and overall comfort isn’t impacted negatively at all.
Cleaning and maintenance
PAPR respirators must be cleaned and maintained correctly. Before investing, understand the masks maintenance requirements and make sure your fabricators are trained to carry out the appropriate checks.
Filters and spare parts
Filters are consumable components, and batteries, visors, seals, hoses and other parts may eventually require replacement. Check the availability of replacement filters and spare parts before investing in a PAPR system – especially if the equipment will be used every day.
Which PAPR is best for stone fabrication?
There is no single PAPR that is automatically suitable for every stone fabrication process. The correct system depends on factors including:
For engineered stone, current HSE guidance specifies powered air-purifying respirators with an APF of at least 20 when processing the material, cleaning or maintaining machinery.
The appropriate RPE should be selected as part of the workplace COSHH assessment. Where that assessment identifies the need for a higher level of respiratory protection, a suitable system with a higher Assigned Protection Factor may be required.
Stonegate supplies PAPR respirators for stone fabricators, including the Optrel Swiss Air and the Skytec Sentinel.
Our team can help you compare the specifications and practical differences between the available respirators, to ensure you invest in the right option for your fabrication requirements. Or visit the relevant pages on the HSE website for more information:
https://www.hse.gov.uk/respiratory-protective-equipment/what-is-rpe.htm
https://www.hse.gov.uk/stonemasonry/working-engineered-stone-control-silica-risk.htm
Is a PAPR enough to control silica dust?
No. A PAPR protects the wearer; it does not prevent respirable crystalline silica from being generated or control its spread through the workplace. RPE should therefore form part of a wider system of measures designed to prevent or adequately control exposure to silica dust.
For engineered stone, current HSE guidance includes measures such as selecting materials with lower crystalline silica content, using effective water suppression, controlling mist, providing suitable RPE, maintaining effective housekeeping procedures and providing health surveillance where required.
HSE’s current guidance states that dry cutting of engineered stone is unacceptable. Providing workers with PAPR does not make an otherwise inadequately controlled process acceptable. RPE is the last line of protection and should be used alongside effective measures to control exposure at source.
Need help choosing a PAPR respirator?
Choosing the correct respiratory protection for stone fabrication involves more than comparing individual products. At Stonegate, we can help you understand the differences between PAPR systems, protection ratings, masks, filters, battery performance and replacement parts, to ensure you invest in the right system for your fabricators and fitters.
You can speak to your rep to arrange a trial on site at your factory, or book a visit to our Innovation Hub where you can try out the options we have available! Get in touch on +44 (0) 1482 62040 or [email protected] for further information.
PAPR stands for Powered Air Purifying Respirator. A PAPR uses a battery powered fan to filter contaminated air and supply clean air to the wearer.
A suitably selected PAPR can provide respiratory protection against respirable crystalline silica when it has the appropriate filter and Assigned Protection Factor for the task. Current HSE guidance for working with engineered stone specifies powered air-purifying respirators with an APF of at least 20 when processing the material, cleaning or maintaining machinery.
TH3 provides a higher level of assigned protection than TH2 for powered hoods and helmets classified under BS EN 12941. In the UK, TH2 corresponds to an APF of 20 and TH3 to an APF of 40. However, the appropriate classification depends on the hazard, task and level of protection identified by the workplace COSHH assessment.
APF 20 means correctly selected and worn RPE is intended to reduce exposure to one twentieth of the concentration outside the respirator. APF 40 provides a higher level of protection, reducing exposure to one fortieth.
A PAPR should not be used as justification for dry cutting or polishing engineered stone. HSE’s current guidance states that dry cutting of engineered stone is unacceptable and expects effective water suppression or an equally effective means of controlling exposure. Suitable RPE should be used alongside these control measures; it is not a substitute for controlling silica dust at source.
