Innovation in Respiratory Protection Systems

Investing in high-performance respiratory-protection technologies not only supports employee health and safety, but also strengthens the reliability and resilience of companies’ operating systems and workflows

In countless sectors of the economy, workers are exposed to risks to their respiratory systems. These range from mists (liquid aerosols) to dusts (solid particles, such as wood, flour or soot) and gases (such as sulfur dioxide) to vapors. These consist either of gaseous substances that are liquid or solid at 20°C and 1 bar, such as solvent vapors and mercury vapor, or of aerosols such as nickel monoxide, which are produced by combustion.

The potential consequences of human exposure to these hazardous substances range from asbestosis and occupational asthma, through allergies and silicosis, to chronic obstructive pulmonary disease (COPD) and even cancer — such as mesothelioma (a malignant tumor of the pleura), which is typically associated with asbestos exposure.

It is not only the victims who suffer from such illnesses. Exposures are also detrimental to the companies concerned: failure to comply with internal or even statutory regulations can lead to sanctions — in the worst case, to fines or even claims for damages. Accidents almost always result in downtime and thus lower productivity and inefficiency. A dissatisfied workforce is generally less motivated, absences are prolonged, or skilled workers cannot be found in the first place.

In the U.K., the E.U., the U.S. and other regions, comprehensive safety regulations for PPE therefore apply to hazardous environments, such as those in the chemical and pharmaceutical industries. In this context, the wearing of respiratory protective equipment is often mandatory, and such equipment is classified within a complex system of protection factors. However, many conventional respiratory-protection systems are either highly efficient but heavy and bulky, or they offer ideal wearability yet only comparatively low protection factors. Modern powered air-purifying respirator (PAPR) systems (Figure 1) can combine the advantages of both technologies.

 

Protection factors in industry

Protection factors are generally established at national (or, for example, the E.U.) level by government-recognized bodies. They can vary significantly from country to country, but nevertheless provide a sound basis for selecting respiratory protection masks and are often even the legally prescribed standard.

The nominal protection factor (NPF) provides information on the theoretical performance of respiratory protection equipment. It is derived from the maximum permissible leakage that is defined for a specific protection class (for instance, FFP 1, 2, or 3 for filtering facepieces) in the relevant standard. However, this is a theoretical value determined under ideal laboratory conditions. If a device has an NPF of 50, this theoretically means that the air inside the mask is 50 times cleaner than the outside air.

In practice, the NPF is similar to a car manufacturer’s fuel consumption figures, which in reality almost always perform worse than on paper. In the case of a respirator, however, this is because ‘soft factors’ — such as beard stubble, sweat, slipping or an improper fit — that occur regularly in practice and cannot be simulated under laboratory conditions.

This is why the assigned protection factor (APF) or the actual protection factor is also taken into account. This is the value that the wearer of a protective mask can rely on in practice. And, consequently, the company purchasing the relevant technology can rely on it as well. The APF is based on measurements and average values from practical use. In Germany, for example, these values are generally set at 112–190 by the German Social Accident Insurance (DGUV). Safety engineers use the APF to calculate whether a particular piece of respiratory protective equipment is suitable for a specific high-risk environment.

The minimum required protection factor is the quotient of the concentration of a hazardous substance in the air to the permissible limit value — that is, the concentration classified as medically safe for a person. In the U.K., the Workplace Exposure Limit (WEL), and in Germany, the workplace limit value (AGW), define the time-weighted average concentration of a substance in the air at which no acute or chronic health damage is to be expected.

The concentration of gases, where the volume ratio is decisive, is measured in ppm (parts per million). Milligrams per cubic meter (mg/m³) is the unit for solid substances, such as wood, soot or flour. It provides information about the actual weight of the dust in the air. If the concentration of hazardous substances in the air is 200 mg/m³ with a limit value of 5 mg/m³, the minimum required protection factor is 40.

An FFP 3 mask with an APF of 30 is therefore no longer sufficient in such an environment, even though its NPF is 50. This is why purely nominal values reach their limits in practice. APF values, on the other hand, are an appropriate reference system, as they are determined through workplace simulations.

 

Typical systems and uses

Conventional respiratory-protection systems are divided into two categories: devices that use ambient air (air purifying respirator, or APR) and self-contained systems. The latter include classic compressed-air devices, such as a self-contained breathing apparatus (SCBA), often used by the fire service or divers. Users carry compressed-air cylinders on their backs; a pressure regulator reduces the cylinder pressure (usually 300 bars) to a medium pressure that is easy to breathe. This is an open-circuit system, and with an operating time of 30 to 45 min, its use is extremely limited.

In contrast, there are closed-circuit breathing apparatus (CCBA) devices. The exhaled air is not vented, but is rather recycled within the device. A chemical absorber (usually calcium hydroxide and sodium hydroxide) binds the CO₂; fresh oxygen is added from a small oxygen cylinder or via a chemical reaction. Such devices allow for operations lasting 2 to 4 h and are often used by mine rescue teams. However, the breathing air becomes warm and dry over time, and the technology is complex to maintain. Furthermore, these are full-face masks with negative pressure that seal airtight against the face, making breathing very strenuous and causing the wearer to tire quickly. Added to this is the total device weight of 10 to 18 kg.

APR systems in the form of filtering half-masks, on the other hand, are generally lightweight and comfortable to wear, as no additional hardware, such as compressors or compressed-air lines, is required. They allow for high mobility and long operating times, but have only low actual protection factors. For example, some full-face gas masks may offer a nominal protection factor of 2,000, but an actual APF value of just 20, according to the European standard EN 529.

Furthermore, independent and ambient-air systems promote the build-up of moisture and heat, which often leads to sweating, discomfort and heat stress — and consequently to reduced working time. This also increases the risk of non-compliance with regulations in practice, for example by the respirator being removed prematurely.

 

Advantages of PAPR systems

PAPR systems operate on the principle of positive pressure and offer advantages in terms of wearability, operating times and dynamic activities. The main advantage of the PAPR is that the wearer of the respirator does not have to overcome the filter’s resistance.

The battery-powered fan in these systems actively draws in ambient air (Figure 2). The air is forced through the filters and stripped of particles, vapors and gases before entering the headpiece. PAPR devices are always approved as an entire system, of which the filter is a part. Consequently, particle filters do not have the usual P1, P2 or P3 classification. Instead, the entire system is classified according to its protection factor.

Nevertheless, the key factor is the positive pressure principle. The fan delivers more air into the headpiece than the wearer actually inhales. This creates a slight positive pressure inside the mask, hood, visor or helmet. This means that even if the headpiece does not seal perfectly against the face, clean air flows outwards without contaminated air entering from outside.

As a constant flow of fresh air is directed over the face, a cooling effect is created. This prevents the build-up of heat typical of other devices and the fogging of the visor, which is often a problem with conventional masks.

The advantages of PAPR systems over APR systems using half-masks and full-face masks are particularly evident when used in combination with particle, gas and combination filters. Furthermore, PAPR devices are an excellent alternative to FFP 1, 2 and 3 masks, particularly in the chemical and pharmaceutical industries. They combine virtually no breathing resistance with both a high protection factor and maximum wear time — with special hoods, visors or helmets that are usually also suitable for bearded wearers.

 

Suitability of PAPR devices

Device series based on modular platforms offer particular added value for industry. They can be easily adapted to different risks and areas of activity, are robust, easy to clean and can be integrated into existing PPE (personal protective equipment) concepts for eye and face protection, as well as hand, body, respiratory and hearing protection. This holistic modularity enables systems tailored for specific environments and applications (Figure 3).

Consider, for example, a PAPR with a clean particle filter and a TH3- or TM3-rated respiratory interface without gas or vapor filtration. TH3 rating indicates compliance with EN 12941 and TM3 rating corresponds to compliance with EN 12942. This system is therefore not suitable for explosion protection in accordance with the ATEX direction, but represents a high-performance alternative for particle-based applications. In the chemical and pharmaceutical industries, it could replace FFP 1, 2 and 3 masks, offering wearers comfort and a high level of protection.

Other PAPR devices may achieve a real protection rating of 40 when used in combination with a hood or helmet in accordance with U.K. Standard 12941. This is twice as high as the 20 APF of FFP 3 masks. Such equipment is typically used where there is exposure to dusts, powders or aerosols, without any risk from gases or vapors.

In the chemical industry, these applications include powder handling and filling processes, decanting and transfer operations, as well as cleaning, maintenance and ancillary tasks that do not involve explosion or gas risks. In the pharmaceutical industry, PAPR units ensure safety and efficiency when handling active ingredients and excipients in powder form and during tableting, granulation, sieving, mixing, sampling and in-process controls, as well as during cleaning and change-over operations. This also includes activities involving particulate active ingredients (including highly potent active pharmaceutical ingredients, HPAPI), provided there is no gas or explosion risk (Figure 4).

The advantages of these systems are clear: significantly lower inhalation and exhalation resistance, no fogging of glasses, high user acceptance during prolonged wear, and a stable, effective protective effect through positive pressure, combined with excellent practical suitability compared to FFP masks.

 

Protection and user acceptance

The statistics on respiratory diseases and deaths worldwide speak for themselves. With such work-related accidents and consequential damage, there are only losers. First and foremost, of course, are those affected themselves. But every workplace accident and every illness is also a problem for the company in question: such incidents usually cause uncertainty among the workforce and undermine motivation. Added to this are frequent regulatory investigations — and with them, as a rule, the shutdown of a production section or even the entire plant. This, in turn, can have a direct impact on the process stability and productivity of the entire operation: downtime costs companies money.

Companies should therefore consider how they can significantly improve the safety of their employees. The key in this context is the direct link between comfort, acceptance and safety. Mechanical faults and the resulting accidents and consequential damage will never be entirely avoidable. However, the most important tool for greater safety is consistent compliance by employees.

Conventional respiratory-protection systems can often cause stress: high breathing resistance, heavy weight, heat and sweating are often added to the mix. Even in the areas where traditional FFP masks are used — from the chemical and pharmaceutical industries to woodworking and construction — a subjective feeling of insecurity can arise, for example, from a suboptimal fit. Here too, breathing resistance is higher than in a positive-pressure system, and a feeling of stuffiness is not uncommon.

Thanks to their positive pressure principle, PAPR systems ensure improved comfort and, as a result, much higher acceptance. The constant, gentle draught is generally perceived as pleasant; it prevents sweating and the visor from fogging up. This, in turn, means that employees are far more willing to strictly adhere to all regulations on PPE. Moreover, this has the potential to significantly reduce incidents and exposures that pose a health risk. Increased motivation and willingness to perform among employees included.

So, investing in innovative respiratory protection technology not only promotes the safety and health of your employees. It also invests in the safety of the company’s own systems and workflows — and thus in process stability and, ultimately, in the company’s own economic health and resilience. ■

Edited by Mary Page Bailey

 

Acknowledgement

All images provided by author

 

Author

Stefan Mixa is global product manager at DRÄGER Safety AG & Co. KGaA (Revalstrasse 1, D-23560 Lübeck, Germany; Phone: +49-451-882-0; Email: presse@draeger.com; Website: www.draeger.com). With more than 20 years of experience in global product management in the medical and safety fields, he is currently responsible for new product developments of PAPR products. He holds a diploma in business administration and mechanical engineering from the University of Kaiserslautern, Germany.