Miller Magazine Issue: 116 August 2019

83 ARTICLE MILLER / AUGUST 2019 rator with a filter cartridge, usually a half-face mask covering the mouth and nose. Both will have an as- signed protection factor of up to 10. They can be combined with goggles or obtained as a whole-face mask to protect the eyes as well. Usually, whole-face mask will have an assigned protection factor of up to 50 (Wikipedia, 2019). For prolonged exposure times such as a rescue procedure during accident, remote breathing appa- ratus should be used. The simplest form is a flexible tube of about 25 mm internal diameter connected to the mask on the wearer’s face and opening in clean air. This should be used for distances of maximum 9 m long, distances greater than that will be too long for natural breathing. For applications requiring ex- tended filter life, some respirators are equipped with hose adapter that allows two fitted filters to be belt mounted and oriented away from the source of con- tamination, further reducing breathing resistance and increasing filter life (Walter et al., 1999). A more advanced form of mask is the powered RPE or Powered Air Purifying Respirator (PAPR). This res- piratory protection device uses a fan to deliver filtered air into a variety of different headgear and facepiece options. A PAPR is battery-powered and comes in many configurations to make sure the wearer is com- pletely comfortable, regardless of the workplace or environment (Wikipedia, 2017). PAPR will enable protection from couple of hours to up to twelve hours with an assigned protection fac- tor of up to 1,000. Some of the brands incorporate a downloadable data-logging function that automat- ically records usage and performance information - making record keeping much easier. Usually they will supply a continuous airflow of 160 l/min (Wikipedia, 2017). When there is an immediate danger to life and health, the highest form of respiratory pro- tection is the Self-Contained Breathing Apparatus (SCBA) and pressure demand supplied air will protect the wearer for 30-75 minutes with an assigned protec- tion factor of up to 10,000. SCBA is equipped with cylindered air (Wikipedia, 2019b). Whether it’s a half-mask, a whole-mask (non-powered respirators), powered RPE or SCBA it is most important that the mask would fit properly. Wearer must be shaved. Each time the mask is put on, a check must be carried out to ensure that the rubber face piece is giving a good seal on the face. This is done easily by pinching the hose of the respirator or sealing the opening of the cartridge. If it fits properly then the wearer will not be able to breath as the mask will collapse against the face. Filter cartridges There are various filter cartridges available today in the market which gives protection against dusts, sprays, organic and inorganic vapors. All of them supply protection for short exposure time and low concentrations. Each cartridge would be marked on which specific toxicant it protects from and the de- gree of protection (marked from 1-3, where 3 symbols greater protection). Each cartridge has a maximum shelf-life of 6 months after it is opened. After each fumigation procedure cartridge should be removed from the mask and kept in a tight container when not in use. The mask should be washed and left to dry. It is most important to manage a list of the time used with the filter with all types of the non- PAPR to ensure wearer safety (Walter et al., 1999). Table 2 shows the color and letters coding of filters indications for each group of substances or particles. These could also be found in the market as combination filters which have more than one color code and letter code. For phosphine, operator would use “B” grey filter, for MB, EF, EDN and PPO “AX” brown filter. Most labels will recommend using ABEK P3 which is more expensive and protects also against high concentration of par- ticles (P3). Table 2: Color and letter codes of filters indications for each group of substances or particles.