For the purposes of this article, the following terms shall have the meanings respectively ascribed to them by this section:

(1) OCCUPATIONAL DISEASE. A disease arising out of and in the course of employment, including occupational pneumoconiosis and occupational exposure to radiation as defined in subdivisions (2) and (3), respectively, of this section, which is due to hazards in excess of those ordinarily incident to employment in general and is peculiar to the occupation in which the employee is engaged but without regard to negligence or fault, if any, of the employer. A disease, including, but not limited to, loss of hearing due to noise, shall be deemed an occupational disease only if caused by a hazard recognized as peculiar to a particular trade, process, occupation, or employment as a direct result of exposure, over a period of time, to the normal working conditions of the trade, process, occupation, or employment.

(2) OCCUPATIONAL PNEUMOCONIOSIS. A disease of the lungs caused by inhalation of minute particles of dust over a period of time, which dust is due to causes and conditions arising out of and in the course of the employment, without regard to whether the causes or conditions are inherent in the employment or can be eliminated or reduced by due care on the part of the employer. The term "occupational pneumoconiosis" shall include, but without limitation, such diseases as silicosis, siderosis, anthracosis, anthrasilicosis, anthracosilicosis, anthraco-tuberculosis, tuberculosilicosis, silico-tuberculosis, aluminosis, and other diseases of the lungs resulting from causes enumerated in this section.

(3) OCCUPATIONAL EXPOSURE TO RADIATION. Gradual exposure to radiation over a period of time from the use of or direct contact with radium, radioactive substances, roentgen rays (X rays), or ionizing radiation, arising out of and in the course of the employment and resulting from the nature of the employment in which the employee is engaged, without regard to whether the exposure is inherent in the employment or can be eliminated or reduced by due care on the part of the employer.

(4) NATURE OF EMPLOYMENT. With respect to subdivisions (2) and (3) above, this term shall mean that, as to the industry in which the employee is engaged, there is attached a particular hazard of the exposure that distinguishes it from the usual run of occupations and is in excess of the hazards of the exposure attending employment in general.

(5) CONTRACTION OF AN OCCUPATIONAL DISEASE. This term shall include any aggravation of the disease without regard to the employment in which the disease was contracted.