Amends the Workers' Compensation Act. Provides that the rebuttable presumption concerning specified conditions or impairments of health of an employee employed as a firefighter, emergency medical technician, emergency medical technician-intermediate, advanced emergency medical technician, or paramedic is intended to shift the burden of proof to the employing entity and any party attacking the presumption must establish by clear and convincing evidence an independent and non-work related cause for the condition or disability and prove that no aspect of the employment contributed to the condition. Provides that the rebuttable presumption relating to hearing loss cannot be overcome with evidence allegedly showing that the injured employee did not meet specified exposure thresholds.