The Environment Agency, UK Automated Urban and Rural Network (AURN) network contractors are in the process of updating the health and safety advice regarding the Met One 1020 Beta Attenuation Monitor (BAM) PM10/PM2.5 monitoring instrument. As BAMs are used within the SAQD this update is relevant to Scottish Local authority sites.
The BAM contains a small, sealed radioactive source of beta radiation (carbon 14, or 14C). Although carbon 14 is dangerous if it gets inside the body (if swallowed, inhaled or absorbed through the skin), that is not a risk here, because the source is sealed and safely contained inside the BAM.
However, it has come to our attention that, when the door of the case is open, a detectable amount of beta radiation emerges from the BAM, through the slit between the tape and the source, probably having been scattered by the tape and the material on it.
The beta radiation from 14C is of relatively low energy; it cannot penetrate through the case of the BAM, can only travel around 22 cm through air, and – most importantly - cannot penetrate even the outer layer of your skin.
However, it is known that direct exposure of the lens of the eye to beta radiation can increase the risk of developing the eye condition of cataracts (where the lens becomes opaque). This is a known risk for people whose eyes are directly and frequently exposed to beta radiation (such as health professionals regularly carrying out certain medical imaging procedures).
When carrying out BAM maintenance tasks such as nozzle cleaning or tape changing, the operator will have the door open and may have their eyes close to the tape slit. While it is currently our understanding that any risk is very small, (because of the low energy of the beta radiation, and because such tasks are infrequent and do not take long), as a precaution we are recommending that safety glasses are worn when carrying out such tasks.
We are therefore making the following recommendations to Local Site Operators and others who carry out work on a BAM1020 that involves opening its door:
- Do not attempt to access, modify or remove the BAM’s sealed beta source for any reason.
- It is recommended (but not essential) to wear safety glasses when working on the BAM1020 with its door open. As well as offering more than adequate protection for the extremely small risk of any eye damage from the beta source, this will also minimise any other eye risk from other maintenance activities such as cleaning nozzles etc.
The Air Quality Monitoring in Scotland Sites Operates Manual found on the Air Quality in Scotland Website is in the process of being updated with this information.
If you have queries regarding this issue or require additional information, please do not hesitate in contacting any of the Ricardo Energy and Environment Air Quality team.