(a) A "responsible operator" is the operator which is determined liable for the payment of benefits under this part for any period after December 31, 1973. In order for an employer to be considered a responsible operator in any case, the following shall be established:
(1) The miner's disability or death shall have arisen at least in part out of employment in or around a mine or other facility during a period when the mine or facility was operated by such operator, except as provided in 725.493(a)(2);
(2) The operator shall have been an operator of a coal mine or other facility for any period after June 30, 1973;
(3) The miner's employment with the operator or other employer shall have included at least 1 working day (725.493(b)) after December 31, 1969; and
(4) The operator or the employer shall be capable of assuming its liability for the payment of continuing benefits under this part, through any of the following means:
(i) By obtaining a policy or contract of insurance under section 423 of the Act and part 726 of this subchapter; or
(ii) By qualifying as a self-insurer under section 423 of the Act and part 726 of this subchapter; or
(iii) By possessing any assets that may be available for the payment of benefits under this part or through an action under subpart H of this part.
(b) In the absence of evidence to the contrary, a showing that a business or corporate entity exists shall be deemed sufficient evidence of an operator's capability of assuming liability under this part.
(c) For the purposes of determining whether an employer is or was an operator or other employer covered by the Act which may be found liable for the payment of benefits to an employee of such employer under this part, there shall be a rebuttable presumption that during the course of an individual's employment such individual was regularly and continuously exposed to coal dust during the course of employment. The presumption may be rebutted by a showing that the employee was not exposed to coal dust for significant periods during such employment.

For purposes of 725.493(a), a year of coal mine employment may be established by accumulating intermittent periods of coal mine employment.