• Identification of all hazardous products on site.
• Control of the hazard by the best methods.
• Communication of the risks and proper training of staff.
• Surveillance of the health of exposed staff.
  

Types of Testing

The following types of testing all help to answer the question, "How well is the air system performing in terms of operator protection from fumes?"

1. Gas Concentration Measurements
There are many different methods of testing for toxic gases. Generally, more involved (more expensive) tests will produce more accurate results. Such testing would be necessary if the process was marginal and if it was intended to continue to operate it in a manner that only just complied with the maximum exposure limits. In radiography, this is not usually the case, and it is possible and desirable that operator exposure to toxic fumes be well under the limits prescribed.

Simple gas concentration measurements are generally sufficient if the measurements are made at a sensible location and at appropriate stages in the process.

The gases of major concern in radiographic processes have been:

• glutaraldehyde (present in some developer solutions)
• acetic acid (major component of some fixer solutions)
• sulphur dioxide (released if fixer solution breaks down)
• New processors may use different chemicals.
  

A check with the supplier of the x-ray film processor and/or the supplier of the chemicals is advisable to determine exactly what substances are present in the process as ingredients or as by-products of the process.

2. Extraction System Tests
An extraction unit is recommended for rooms housing x-ray film processors. The purpose is to safely remove any harmful vapours that do escape from the processor into the room.

The extraction rate should be that specified by the processor supplier. Generally, the guidelines are as follows:

For processors not fitted with a continuously operating extraction system, 300 m3/hr or 15 room air-changes per hour.

For processors fitted with a continuously operating extraction system, 200 m3/hr or 10 room air-changes per hour.

Testing of extraction rate and calculation of room air-change rate for the processor room is therefore desirable.

It is further recommended that the processor room is maintained at a slight negative pressure with respect to adjacent rooms to prevent vapour escaping from the room.

If the processor is installed for "through the wall" film feed from a darkroom, then the dark room must be at a positive pressure with respect to the processor room.

Checking of differential pressures between the processor room and the dark room and other adjacent rooms is recommended.

Sometimes a chemical mixing process or a tabletop processor will be enclosed within a fume cupboard. In this case the fume cupboard should be tested and validated.

3. Overall Ventilation System Check.
The ventilation standard set for darkrooms and recommended for the processor room is 2.5 litres per second of fresh air per square metre of room size.

In theory, up-to-date engineering drawings of the ventilation system will be available, and from these the fresh air supplied to the rooms can be verified. Often, however, the drawings are not available, or not up to date, and direct testing may be required to check the fresh air rates.

Frequency of Testing
Buildings fitted with ventilation systems and/or various safety systems need to be checked annually and a building warrant of fitness obtained. Specialised extraction systems such as fitted over an x-ray film processor and fume cupboards are covered by this requirement, and thus should be tested at least annually by an Independent Qualified Person registered with the local territorial authority.

Fume cupboards should be tested and validated at least annually by an IQP, and checked and maintained every six months according to the applicable standard.

We recommend that in-depth testing should be performed initially, including testing for all possible dangerous gases and a full appraisal of the extraction and ventilation systems. However, after this initial testing, it will often be possible to omit certain test procedures on the basis of certain reasonable assumptions. For example, ongoing testing may only include measurement of the gas concentration of that gas which was found to be most prevalent in the initial study. Other gas tests may be omitted or reduced to a single sample. This is because it is reasonable to assume that if the air control system safely controls this gas, then the other gases are also safely controlled.

Testing Services from Total Air Care
Total Air Care is accredited by International Accreditation New Zealand in the field of controlled environments - such as operating theatres, safety cabinets and fume cupboards. Our accreditation does not yet cover gas contamination testing, but the laboratory disciplines and procedures enforced by International Accreditation New Zealand ensure that testing is conducted in a professional manner.

Total Air Care is currently registered with territorial authorities throughout New Zealand as an Independent Qualified Person for testing of fume cupboards and other specialised air systems.

Total Air Care offers testing packages which we believe are appropriate for the majority of x-ray film processes in New Zealand, We also offer customised testing packages if required.

Our testing provides not only an indication of exposure level to hazardous fumes but also quantitative data on the extraction and ventilation system which should be removing the fumes. This generally highlights any remedial action necessary.

For an automatic x-ray film process, we recommend a full process validation initially and an annual audit thereafter. Our standard test packages for "through the wall" x-ray film processors are as follows:

1. Standard Process Validation: