What kinds of activities is the JAPAN ASSOCIATION FOR WORKING ENVIRONMENT MEASUREMENT (JAWE) engaged in?

The JAWE was founded in 1979 as a specialized technical group concerned with the examination and control of working environments. Its main activities include carrying out working environment research and examination, holding various seminars, and providing technical guidance.

Inquiries skyrocketed after problems concerning asbestos were reported by the mass media. There were so many inquiries that our staff was overwhelmed.

Could you now tell us about the methods for measuring asbestos concentration?

Some time ago, we were asked to measure concentrations of asbestos in a particular working environment. We used an optical microscope (phase contrast microscope) and the count analysis method to measure the concentration of asbestos fibers in a given area, and the figures we came up with were extremely high. We thought these figures were strange considering the conditions of the workplace, so we asked another laboratory to check the samples. It turned out that the material was actually talc.

With an optical microscope we can only observe shapes. At that particular factory, a large quantity of fibrous talc was mixed with the asbestos, so all of it was included in the count. Talc and asbestos are two varieties of the same mineral. Talc's primary component is a hydrous silicate of magnesium.

So it's difficult to identify asbestos just by the shape of the material?

Yes, exactly. An ordinary optical microscope will only let us see shapes. Measurements using X-ray diffractometry, on the other hand, work in the opposite way. They let us use qualitative analysis to identify the material, but we can't identify the shape.

In a directive concerning the method for determining the ratio of asbestos contained in sprays and other fire-resistant building materials issued in 1996, the shape of asbestos fiber must satisfy three conditions: Have a length of at least 5 micrometers; have a width of less than 3 micrometers; and have an aspect ratio between length and width that is at least 3:1. This means that even if the fibers are truly asbestos they are not counted, unless they meet all those conditions.

To take measurements through microscopic observation, we need to be able to determine the composition and shape of the fiber at the same time. Asbestos refers to six types of natural silicate mineral fibers. Three of these, namely chrysotile, amosite, and crocidolite, were mostly used in building materials in Japan. Not only has the dispersion staining method made it possible to measure asbestos, it has also made it possible to identify chrysotile, amosite, and crocidolite.