The several liabilities which may be imposed pursuant to ORS § 448.305, 454.010 to 454.040, 454.205 to 454.255, 454.505 to 454.535, 454.605 to 454.755 and ORS chapters 468, 468A and 468B upon persons violating the provisions of any rule, standard or order of the Environmental Quality Commission pertaining to air pollution shall not be so construed as to include any violation which was caused by an act of God, war, strife, riot or other condition as to which any negligence or willful misconduct on the part of such person was not the proximate cause. [Formerly 449.825 and then 468.300]