Protective clothing and equipment suitable for one material may not be
suitable for others. For example, polyvinyl chloride (PVC) plastic is resistant to most acids, but it can be softened or penetrated by many common solvents such as benzene, toluene, and xylene.

For this reason, a knowledgeable person should assess the protective clothing and equipment needed (e.g., gloves, boots, chemical suits. fire resistant coveralls-as well as hearing, respiratory, eye, and face protection). Don’t forget that if workers need personal protective equipment, they must be trained in its use.

Respiratory protective equipment should be used where ventilation is
impractical or inadequate. Certain basic rules apply to the equipment.

First of all, you need to select the proper type of respirator. Oxygen-deficient atmospheres require supplied-air respirators either airline types with emergency reserves or SCBA (self-contained breathing apparatus). 

Two types of supplied air respirators

1. Airline Type- this is connected to a hose to the respirator that is continuously supplying air.
2. OR Self-Contained Breathing Apparatus (SCBA) this type is connected to an oxygen tank. You are limited by how long the tank of oxygen will last. It may last 10 minutes to half an hour it depends on the tank itself and how you breathe or take in the oxygen. Not all tanks will last the same for everyone, it is individualized. So always try out your SCBA to determine how long a tank will last you. If you are under stress or trying to move fast your breathing will alter and you will use up a tank faster.  SCBA note: Because the amount of air supply in standard SCBA cylinders is rated for a specific time period, it is very important to plan your tasks, especially rescues operations, accordingly. Heavy work and stress will increase breathing rates and workers will use up the air in less than the rated time. An alarm sounds when the air supply is low.
   In toxic atmospheres, you must use supplied-air respirators if the concentration of the gas or vapour exceeds the level considered to be Immediately Dangerous to Life or Health (IDLH), or if the concentration is unknown. When the level of toxic gas or vapour is
   above the exposure limit but below the IDLH level, air-purifying respirators approved by the National Institute of Occupational Safety and Health (NIOSH) may be used provided the exposure
   conditions do not exceed the unit’s limitations. Someone who is competent in respirator selection must determine the appropriate type of respirator. All employees using a respirator are required to be fit tested and trained in its care and use of the equipment.