As used in this chapter, "disablement" means the event of an employee’s becoming actually incapacitated, partially or totally, because of an occupational disease, from performing his work in the last occupation in which injuriously exposed to the hazards of such disease, "partial disability" means the physical inability to continue work in such occupation only and "total disability" means the physical inability to perform work in any occupation. The disablement and disability of an employee from an occupational disease shall be determined as provided in this chapter.