I’m just out of my decontamination shower after removing layers of ancient paint from an old sea chest. The chest is lined with an 1878 edition of The London reader of literature, science, art and general information, so there is a fair chance that the paint has a few toxic components, particularly the black base layer. I’m not daft (thanks to all that mandatory Health and Safety training) and know that such a job requires full PPE (Personal Protective Equipment). Full equipped with my mask, goggles, gloves and overalls I’ve been busy sanding the chest this afternoon but failed to pick up on a weak signal that was my eventual downfall and brought the job to a premature end.

Due to my reduced vision with the goggles I failed to spot the tin of paint sitting on top of the cupboard which was dislodged by the electric extension cable, fell off the edge and straight onto me. Should have had a hard hat as well! I was so busy focussing on the microscopic airborne toxic dust particles that I missed the gallon tin of paint coming my way. Not such a weak signal in the end.

This event reminded me of another dusty story I was told while I was in hospital with pneumonia last summer. One gentleman had worked in an iron foundry during the 1960/70’s and told me about how they would keep the place cool during the summer heat (not that common in South Wales). This involved removing the asbestos roof sheets to let in a breeze. Yes I did say asbestos; they also had drinking water supplied via lead plumbing. This place had just about every health and safety risk going. Workers had very little in the way of PPE; heat-resistant clothing was about the limit.  There were no dust extraction helmets or positive pressure masks, just eight hours a day of breathing what ever was in the foundry atmosphere. Back to the summer ventilation. Once the roof sheets had been removed, the sunlight would stream in and clearly show up just how thick with dust particles the air was inside the foundry building. The attached picture is far better than the reality he described.

I was amazed when he told me what the workers did next. When crossing the foundry floor, they would avoid the sunlit patch (full of dust particles) and walk around it. The patterns of where they walked would also change as the sun changed position during the day. The different routes workers took were all clearly visible via the footprints in the significant quantities of dust and other debris on the floor. The dust was everywhere in the foundry, with not so weak signals like a 20mm thick layer of it on every solid surface. Incredible really that it wasn’t until it became obvious that it was airborne as well, that people did anything about it, even if that was actually a futile act of walking around the sunlit patch.

This was ultimately 19^th Century technology (being used in the late 20^th Century) where the obvious risks were from physical injuries such as burns or crushing from heavy machinery. The effects of the dust particles on the workers was a not so weak signal that either hadn’t been detected or was just being conveniently ignored.  Interesting how things reverse themselves and this afternoon my over concentration on the airborne dust led to me to missing the obvious physical risk.

For a much better explanation of weak signal detection and why it’s important, have look at this post from Dave Snowden and this guest post from Steve Holt on the Cognitive Edge site.

So, what’s the PONT?

1. In planning for the expected you can often miss or ignore the weak signals.
2. You need to have wide awareness if you want to detect weak signals.
3. Its one thing to spot weak signals, but another thing to act upon them (like the foundry dust).