Appeal from a decision and award of the Workmen’s Compensation Board. Deceased was a truck driver for a building supply company. On August 27, 1948, while at work, he became ill and died a short time later. The day was extremely hot and humid with the temperature reaching 99 degrees at about the time of decedent’s illness. The proof is that he picked up and delivered several loads of brick; that he was exposed to the sun during parts of this process; that the truck was fifteen feet long, eight feet wide, had ten wheels, and required considerable exertion to operate; that after he collapsed it was observed that deceased “had a flush and his body was hot and dry ”. The plainly expressed opinion of the doctor who performed the autopsy was that death was due to heart disease and not to heat or to exertion. Other medical evidence is strongly expressed in the same direction. There is, however, proof by a physician based both on the autopsy findings and on the observation of the witness who observed his condition before death that the heat of the day and the effort in the course of the work were contributing factors to the death. These were described by the physician as the “trigger mechanism” which brought on the death. A physician for the Workmen’s Compensation Board expressed the opinion that the heat and exposure and the driving of the truck contributed to the death which itself was caused by heart disease. In view of these differing medical opinions in the record we. would not feel justified in ruling that the board had no basis in substantial evidence in the record to find that there was accidental causation. Decision and award unanimously affirmed, with costs to the Workmen’s Compensation Board. Present — Foster, P. J., Bergan, Coon, Halpern and Imrie, JJ.