(a) There is no legal principle that, in circumstances where successive tortfeasors have exposed a worker to the risk of injury from asbestos over different periods with, perhaps different intensities of exposure and different degrees of toxicity apportionment between them should be equal.
(b) The conventional regard to culpability and causation should not obscure the need to examine the whole conduct of each party, an examination which in circumstances of inability to quantify comparative causal potency could itself lead to differential responsibility by regard to the degrees of exposure.
(c) Such apportionment is not a mathematical exercise and where the responsibilities were not to be distinguished in one respect but were to be distinguished in another respect there is no reason why the distinguishing respect should not be given full effect.
38. The case law has also taken into consideration in making apportionment between tortfeasors in asbestos cases various other distinguishing factors such as:
(a) The lag time between exposure and diagnoses of the disease.
(b) The year and decade in which exposure occurred.
(c) The varying legal relationships between the tortfeasors eg employers; employee, supplier\and user; occupier \ bystander; builder\bystander; subcontracting applier\bystander
(d) The number of tortfeasors
(e) The relative state of knowledge of the tortfeasors as to the dangers of asbestos and the steps that might be taken to minimise harm to workers.