Ok, found it, it is not concidered to be significant if "material which contains less than 1% total lead"

Dear Safetytodo01, You are conflating two separate issues, the amount of lead in the paint and the amount of lead a person is exposed too. The ACoP assumes that if the lead content of paint is less than 1% (W/W), then you cannot get a significant exposure to lead. However this is overly simplistic. As an example, assume you a removing 100 kg of paint, with a lead content of 1% (W/W), from a bridge. This means that there is 1 kg of lead. The work takes 1 week for 10 persons. If you burn off the paint, then some of the paint will be in the form of fume. However, if you grind off the fume, the majority will be in the form of dust. Assume that 1% is in the form of fume then 10 g (1000 g/kg x 1/100) lead will be fume. Over 1 week this means a person's average lead exposure is 25 mg/hr (0.2 g x 1000 mg/g / 40hrs/w / 10 person). To compare this against the 8 hr TWA control limit of 15 mg/m3 , you need to know the volume of air that it is contained within. If you were the paint stripper I would assume 1 m3 on the basis that you are in the near field whilst if you were a helper that the air volume was 10 m3 and if you were the supervisor I would assume 100 m3 as you are in the far field. So the painter would be over the control limit, the helper close to the control limit and the supervisor under the control limit. In this case 100% of the fume is biologically available for uptake once inhaled. If you grind off the dust then assume 10% will be total inhalable dust and therefore everything is multiplied by 10, but the total amount absorbed is around 10% (9% for the pedants) - so the amount absorbed is the same. I hope that this helps and give a flavour of the problem. Regards

Still need a bit more clarity, being simplistic as i'm a believer "simple works". On assessing the removal of existing paint and having had samples taken would I be wrong in assuming that "if below 1% the significant value" no additional controls specific to lead are required. Would it then be safe to say that 1% or above would then trigger additional monitoring to assess the air borne concentration in relation to exposure levels 0.15mg/m3 (0.10mg/m3 for lead Alkylis). Putting it in simple term if 1% of weight is the significant value and I used this as the "significant trigger" for following the process within L132 figure one. Does this satisfy legislation?

Would it be possible to simplify or explain further the formula you stated previously for converting %weight to exposure in mg/m3. I'm not the most mathematical minded.