Respiratory Protection

Selecting the correct protection

The selection of Respiratory Protection follows a basic four-step method:

• Identify the Hazards - dust, metal fume, gas, vapour
• Assess the Hazards - assess the hazard level/other protection - skin and eye
• Select the proper Respirator - disposable, half mask, full face, powered, airline
• Training in fitting and use - to optimise respiratory protection

RESPIRATORY HAZARDS

Dusts - produced when solid materials are broken down into finer particles, the longer the dust remains in the air the easier it is to inhale.

Mists - tiny liquid droplets formed by atomisation and condensation processes such as spraying. Mists are often combinations of several hazardous ingredients.

Metal fumes - occur when metals are vaporised under high heat. The vapour is cooled quickly and condenses into very fine particles that float in the air.

Gases - airborne at room temperature. Able to diffuse or spread freely, can travel very far very quickly.

Vapours - gaseous state of substances that are liquids or solids at room temperature. Formed when substances evaporate in the way water vapour evaporates from water.

CoSHH (Amendment) REGULATIONS 2004

These Regulations serve to amend, not replace, the current CoSHH Regulations 2002. There are a number of changes, the two most significant being:

• The inclusion of the new framework of control and introduction of eight principles of good practice for the control of hazardous substances.
• The replacement of the current Occupational Exposure Limit (OEL) system, which included two definitions - Maximum Exposure Limit (MEL) and Occupational Exposure Standard (OES) - with a new system that has just one definition, Workplace Exposure Limit (WEL).

The WEL for a given substance should not be exceeded. The HSE, however, have specified certain groups of substances where exposure should be as far below the WEL as is reasonably practicable. These substances include those that cause cancer, respiratory sensitisation or heritable genetic changes.

These changes have led to two new publications:

• Control of Substances Hazardous to Health Regulations 2002 (as amended), 5th edition. ISBN 0 7176 2981 3.
• EH/402005 - Workplace Exposure Limits. ISBN 0 7176 2977 5.

RESPIRATORY TERMINOLOGY

Workplace Exposure Limit (WEL)

Airborne concentration of a Hazardous Substance, averaged over a specified time period referred to as a Time Weighted Average (TWA).

WEL Time Periods

There are two reference periods for which WELs may be set; 8 hour Time Weighted Average (TWA) and 15 minute Short Term Exposure Limit (STEL). A substance may be assigned WELs at either one or both reference periods.

• 8 hour TWA - some adverse health effects can occur after prolonged or accumulated exposure. The 8 hour TWA is set to restrict the total intake by inhalation over one or more shifts.
• 15 minute STEL - Some adverse health effects may be seen after short exposures. 15 minute STEL may be applied to control these effects.

Immediately Dangerous to Life or Health (IDLH)

The IDLH concentration of a substance is defined as "that which poses a threat of exposure to airborne contaminants when that exposure is likely to cause death or immediate or delayed permanent adverse health effects or prevent escape from such an environment". The IDLH value represents a maximum concentration from which a worker would escape within 30 minutes without any impairing symptoms or irreversible health effects.

Odour Threshold

The concentration of a substance at which the majority of individuals can smell or taste it.

TYPES OF RESPIRATORY PROTECTIVE EQUIPMENT

Each type of RPE has specific limitations which dictate the types of application for which it may be used. RPE is tested to relevant European Standards which determines the product performance.

RPE SELECTION CALCULATION

Personal Air Monitoring information, when compared to the relevant WEL for that hazardous substance, helps to more accurately determine the required level of respirator protection factor.

For example: Woodworking

1. Measured Levels (Wood Dust) = 60mg/m³ over 8 hours TWA.
2. Workplace Exposure Limit (WEL) for wood = 5mg/m³.
3. Divide (1) by (2). ⁶⁰/₅ = 12.
4. This figure of 12 is the level at which the hazard is above the WEL, i.e. the Hazard Level is 12×WEL.
5. Assuming all other control measures have been considered, including the 8 new principles of good practice, select a respirator with an APF greater than 12 (e.g. 3M 9332 which has an APF of 20).
6. Ask yourself the further question ‘Do I need to lower levels as far below the WEL as is reasonably practicable?’; i.e. is this substance one of the group of substances that can cause cancer, sensitisation or heritable genetic change? In this case, wood dust is a carcinogen and therefore levels should be lowered as far below the WEL as is reasonably practicable. Therefore, if all other control measures have been considered, an even higher performing respiratory protection product should be contemplated. However, always remember that RPE should be the last resort and that one of the main principles of RPE selection should be that it is "suitable to the job and the wearer".

FILTERS

Filter Markings
For use against	Filter Type	Colour Code	Main Applications
Gas & Vapour (EN 141 & EN 405)	A	Brown	Organic Vapours with boiling point greater than 65°C & good warning properties
	B	Grey	Inorganic gases and vapours e.g. Chlorine (not carbon Monoxide)
	E	Yellow	Acid gases and vapours, e.g. Sulphur Dioxide, Hydrogen Chloride
	K	Green	Ammonia and organic ammonia derivatives
	P	White	Particulate
Particles (EN 143 & EN 149)	P1	White	Protection against particulates
	P2	White	Protection against particulates
	P3	White	Protection against particulates
Gas & Vapour (EN 371)	AX	Brown	Certain organic compounds with boiling points less than 65°C & good warning properties