Control measures for chemicals

Personal protective equipment – chemical exposure

The personal protective equipment required depends on the type of chemical compound used in any given process, and the protection necessary to reduce exposure to acceptable levels.

When selecting gloves one has to take into account that different glove materials provide different levels of resistance to the effects of hazardous chemicals. This is related to the ability of the chemical to penetrate, degrade and/or penetrate through the glove material. A range of different glove materials exists, such as latex, nitrile, PVC and neoprene. Glove charts are available from the manufacturers to assist in selecting type of gloves to use when working with chemicals. However, expert knowledge is needed to make the appropriate choice for particular task and chemicals.

Similarly, there is a broad range of different types of personal respiratory protective devices (respirators). Air Purifying Respirators are of two main types. These are effective against either:

• contaminants in particulate form or
• contaminants in gaseous or vapour form

There are also combination filters (particulate and gas or vapour) for use where both hazards are present.

The recommended type of air purifying respirator to use also depends on the levels of protection needed for the particular contaminant. The protection level increases from disposable half-masks to reusable half-masks and full-face masks.

Disposable halfmask. ^{© G. Tjalvin}

Reusable half mask. ^{© G. Tjalvin}

Full-face mask. ^{© G. Tjalvin}

Powered masks; Contaminated air is drawn through the filter by a fan. As illustrated in the photo the filter and the fan are attached to the belt and worn at the back. Filtered air is then delivered to the space enclosed by the head covering. These devices are often called Powered Air Purifying. ^{© G. Tjalvin}

Filter cartridges for particles, gases and vapours have colour codes to indicate which contaminant they protect against. For instance the brown filter cartridges are effective against vapour from organic solvents in paint products. There are class 1, 2 and 3 which codes for increasing absorption capacity.

Particle filters have a white colour code while the three classes, P1, P2 & P3, indicate increasing filtering efficiency.

An example of a combination filter is the Red & White cartridge, which protects from mercury and particles.

Filter cartridges for gases and vapours have colour codes to indicate which contaminant they protect against.^{© University of Bergen/Arjun Ahluwalia}

The composition of combination filters can be tailored according to the gases, vapour and particles they should protect against.

An example of a reusable half mask with combination filter, as indicated by the colour codes on the filter cartridge.^©Colourbox

For situations involving insufficient oxygen, an Air Supplied Respirator is needed to deliver breathing-quality air to the wearer from an independent source (airline or self-contained breathing apparatus). A supplied-air respirator is the preferred respirator for use when spray painting with isocyanate-containing paint. Supplied air respirators are generally considered to offer more protection than air-purifying respirators with filters, as long as the former are well-maintained and worn properly. The head or face pieces for supplied-air respirators come in several types, including half- or full-face masks, hoods, and loose fitting face pieces.