6.—(1) Subject to sub-paragraph (2), an activity is not to be taken to be a Part B activity within Part 2 of this Schedule if it cannot result in the release into the air of a substance listed in sub-paragraph (3) or there is no likelihood that it will result in the release into the air of any such substance except in a quantity which is so trivial that it is incapable of causing pollution or its capacity to cause pollution is insignificant.
(2) Sub-paragraph (1) does not apply to an activity which may give rise to an offensive smell noticeable outside the site where the activity is carried on.
(3) References to, or to the release into the air of, a substance listed in this paragraph are to any of the following substances—
(a)oxides of sulphur and other sulphur compounds;
(b)oxides of nitrogen and other nitrogen compounds;
(c)oxides of carbon;
(d)organic compounds and partial oxidation products;
(e)metals, metalloids and their compounds;
(f)asbestos (suspended particulate matter and fibres), glass fibres and mineral fibres;
(g)halogens and their compounds;
(h)phosphorus and its compounds;
(i)particulate matter.