Respiratory air filters

These masks do not protect the wearer against noxious or toxic vapours in the atmosphere. Where people are required to work in such an environment, then normal practice is for the wearing of a hood, connected to a compressed air supply, carrying air purified to respiratory air standards. The purity requirements for compressed air used for respiration and hygienically critical applications such as hospital patient recovery. 

The most common method of producing compressed air for human respiration is by the compression of normal atmospheric air. Compressors used for this purpose may be of rotary or centrifugal, coaxial saew, piston or diaphragm type. The choice of compressor will depend on the pressure at which the air is to be used and the volume rate of air delivery required. 

The minimum delivery requirement for breathing air is 1201/min of free air per person, with a higher figure desirable. Pipelines, filters and pressure reducing valves must 

The problems of contamination of breathing air largely echo those already described in the treatment of working snpplies of compressed air, with perhaps greater emphasis on gaseons imparity removal, especially carbon monoxide. 

Oil aerosol or oil vaponr is present in atmospheric air as an airborne effluent from industrial processes and exhanst emissions. Lnbrication in compression chambers invariably means there will be oil aerosols or vapour present in the ouqtut from the compressor. 

---

Particles are present in outdoor air and are also generated indoors from a large number of sources including tobacco smoking and other combustion processes. Particle size, generally expressed in microns (10-6 m) is important because it influences the location where particles deposit in the respiratory system (U.S. Environmental Protection Agency 1995), the efficiency of particle removal by air filters, and the rate of particle removal from indoor air by deposition on surfaces. 

The collection of air samples using air tubes and/or filters is of value during the course of the field research when performing SDDBM studies. The air tube/air filter data can be used to estimate the portion of the total body burden, which originates from respiratory exposure to the active ingredient. Of course, if an organic vapor respirator is used by the worker as a matter of course, the respiratory exposure component should be backed out of the final exposure calculation. 

High-efficiency particulate air filters can remove lightweight particles such as pollens, mold spores, and cat allergen, thereby reducing allergic respiratory symptoms. 

When an individual breathes in polluted air, any substance may enter the respiratory tract causing direct harm to the respiratory system and indirect harm due to uptake via ingestion. Especially sensitising substances may require attention. As airways and the lung caimot be closed off, only ventilation (exhaustion) and filtration of inhaled air remain as protective measures, such as working in safety cabinets and wearing masks with air filters (respirators). 

Our complete line of respiratory protection equipment includes powered air purifying respirators, airline respirators, pressure demand systems, supplied air filters and monitors, and a full range of breathing air pumps. Bullard respiratory products meet NIOSH standards and provide high-quality protection to workers in the Healthcare, Pharmaceutical, Painting, Blasting and Grinding industries. 

Inhaled particles can be labeled with a variety of radionuclides, emitting P-rays or y-rays. The P-rays are highly absorbed from tissue, so that they are almost undetectable from outside the body. With P-emitting radionuclides (e.g., or C), particle deposition in the respiratory system or in the mouth can be assessed only from radioactivity recovered on expired-air filters or in lavage fluid from mouth washings. 

Because a filter sample includes particles both larger and smaller than those retained in the human respiratory system (see Chapter 7, Section III), other types of samplers are used which allow measurement of the size ranges of particles retained in the respiratory system. Some of these are called dichotomous samplers because they allow separate measurement of the respirable and nonrespirable fractions of the total. Size-selective samplers rely on impactors, miniature cyclones, and other means. The United States has selected the size fraction below an aerodynamic diameter of 10 /xm (PMiq) for compliance with the air quality standard for airborne particulate matter. 

Compressed airline system a faeepieee or hood is eonneeted to a filter box and hand-operated regulator valve whieh is provided with a safety deviee to prevent aeeidental eomplete elosure. Full respiratory, eye and faeial proteetion is provided by full-faeepieee versions. The eompressed air is supplied from a eompressor through a manifold or from eylinders. 

Respiratory Chromosorb air tubes and Gelman filters, air pump... 

It has been demonstrated that it is possible to lower the level of airborne radon progeny by filtering and/or expose the air to an electric field. If the radiological risk is measured by the potential alpha energy concentration (PAEC) or exposure rate, for instance expressed in J m 3 or WL, the level may be lowered to about 10-20 % of the value in untreated air, while the reduced level may only be about 40-50 % of the untreated one if the average dose to a certain part of the respiratory tract, for instance expressed in Gy year 1, is considered. 

---