11. (Replaced, O.C. 501-2011)Exceptions: Section 10 does not apply to the starting of a fire or the soot blowing. The degree of opacity may then, for a maximum period of 4 consecutive minutes exceed 20% but never be equal to or higher than 60% of opacity.
During the operation of a stationary source, the degree of opacity of an emission may also exceed 20% for one or several periods not exceeding 4 minutes in any one hour, but never be equal to or higher than 40%.
R.R.Q., 1981, c. Q-2, r. 20, s. 11; O.C. 501-2011, s. 215.