Personal Protective Equipment (PPE) is any clothing or device designed to protect the wearer from hazards that could cause injury, illness, or death. These items act as a barrier to minimize exposure to chemical, physical, and biological dangers in the workplace. PPE is systematically classified into four distinct levels (A, B, C, and D) based on the degree of protection required against potential hazards.
The Criteria for PPE Classification
The selection of the appropriate PPE level is determined by a thorough risk assessment of the worksite. This assessment focuses on the known concentration and type of hazardous substance, and the potential route of exposure. Protection is differentiated based on safeguarding the respiratory system versus the need for dermal (skin) protection.
The choice between the four levels hinges on whether the hazard is known or unknown, and if the substance presents a significant risk through inhalation or skin absorption. When the identity and concentration of a chemical are uncertain, a higher level of protection is mandated. The severity of the respiratory risk, often measured against an atmosphere that is immediately dangerous to life or health (IDLH), is the greatest factor in determining the required level.
Level A: Maximum Protection Required
Level A represents the highest available level of protection, offering the greatest defense for both the respiratory system and the skin. This gear is selected when a high concentration of hazardous vapors, gases, or particulates is known or suspected. It is also required when the substance poses a significant risk of toxicity through skin contact or absorption.
The Level A ensemble uses a totally encapsulated, vapor-tight suit that prevents contact between the hazardous atmosphere and the wearer’s skin. It includes a positive-pressure Self-Contained Breathing Apparatus (SCBA) worn inside the suit. The SCBA provides a completely independent air supply, making this the only suitable option when the hazard is unknown or the atmosphere is immediately dangerous to life or health (IDLH).
Level B: High Respiratory and Moderate Skin Protection
Level B is designated when the highest level of respiratory protection is required, but a lesser degree of skin protection is adequate. This level is used when the atmospheric concentration is high or unknown, but the substance presents a low dermal absorption risk. Like Level A, the ensemble includes a positive-pressure SCBA to ensure a safe, independent air supply.
The main difference from Level A is the chemical-protective suit, which is non-encapsulating and liquid-splash resistant rather than vapor-tight. This hooded chemical-resistant clothing offers protection against splashes and contact with liquids. Level B is often employed during the initial assessment of a hazardous site where the respiratory danger is clear, but the dermal hazard has not yet been fully characterized.
Level C: Air Purifying Protection
Level C relies on filtering the ambient air, moving away from the independent air supply of an SCBA. It is appropriate only when the type and concentration of the airborne contaminant are known, measured, and determined to be below the IDLH threshold. The environment must also have sufficient oxygen levels for the air-purifying respirator (APR) to function safely.
The APR uses specific chemical cartridges or filters to remove contaminants from the air before it is inhaled. The ensemble includes a full-face or half-mask APR and standard chemical-resistant clothing, such as hooded splash suits or coveralls. Because APRs cannot provide oxygen or filter out unknown substances, Level C cannot be used in atmospheres where the concentration is unquantified or where the substance has poor warning properties like odor or taste.
Level D: Minimal Hazard Protection
Level D represents the minimum acceptable level of protection and is essentially a standard work uniform. This level is only appropriate when the work environment has no known atmospheric hazards and no potential for chemical splashes or contact with hazardous substances. It provides minimal protection against physical hazards and nuisance contamination.
The ensemble consists of typical workplace safety gear, such as coveralls, safety glasses or goggles, steel-toed boots, and gloves. Since no respiratory protection is required, it is strictly used in environments where the hazard assessment confirms the absence of any respiratory or skin absorption risk requiring a chemical barrier. Level D is common in general maintenance, construction work, or administrative tasks on a hazardous site’s perimeter.