(a) If compensation is payable for an occupational disease other than pneumoconiosis or radiation, the only employer liable, if any, shall be the employer in whose employment the employee was last exposed to the hazards of the disease. The employer who is liable shall not be entitled to contribution from any other employer of the employee except one who furnished workers’ compensation for the employee during the employment of last exposure.
(b) If compensation is payable for pneumoconiosis or radiation, the only employer liable, if any, shall be the employer in whose employment the employee was last exposed in each of at least 12 months, within a period of five years prior to the date of the injury, to the hazards of the disease and, in addition, any employer who furnished workers’ compensation coverage during this period.