All appeals are dismissed.

The costs of appeal are assessed against the plaintiffs.

The grounds of appeal are examined.

1. In general, the claimant shall bear the burden of proving the perpetrator's harmful act, the occurrence of the victim's damage, and the causal relationship between the harmful act and the occurrence of the victim's damage;

However, in a lawsuit claiming compensation for damage caused by air pollution or water pollution, etc., requiring the victim to provide a scientific strict proof of the existence of a factual causal relationship may result in the refusal of judicial relief due to pollution. On the other hand, since technical and economic circumstances make it much easy for the perpetrator to investigate the cause of damage rather than the victim, and since there is a concern that the perpetrator may conceal the cause of damage, the perpetrator may recognize the causal relationship between the harmful act and the damage suffered by the victim unless the perpetrator proves that the damage was caused by the occurrence of the damage.

However, in this case, at least the perpetrator discharges harmful substances, the degree of harm exceeds the extent that the perpetrator should generally identify (hereinafter referred to as the “limit of participation”) under the social norms, the fact that it reached the damaged object, and the burden of proof as to the fact that the damage was inflicted on the victim is still borne by the victim.

(see Supreme Court Decision 2012Da111661, Oct. 11, 2013). Whether the degree of harm exceeds the permissible limit should be determined by comprehensively taking into account all the circumstances, including the nature and degree of damage, the public nature of benefits from damage, the form of harmful act, the public nature of harmful act, the public nature of harmful act, the prevention measures against the perpetrator or the possibility of avoiding damage, whether the perpetrator violated the regulatory standards under public law, and regionality.

(See Supreme Court Decision 2011Da91784 Decided September 24, 2015). Meanwhile, the appraiser’s appraisal result is the result.