The only issue in this Workers’ Compensation review is whether the lower court’s decision that the Claimant’s injury arose out of and in the course of his employment is supported by competent evidence. Applying the statutory and case law to the facts before us, we conclude that it is.
Claimant Mooney worked for the Stroud Hospital as a laboratory supervisor. On the date in question he went home for lunch, and had been there fifteen minutes when the Hospital called. He was told to return for an emergency; a man in the Emergency Room was believed to have suffered a heart attack and Mooney was needed for blood work. He immediately headed for the hospital, but on the way his car was hit broadside in an intersection by a driver who failed to yield. Claimant suffered injury to his neck requiring surgery, including a fusion of his vertebra with a bone graft from his hip.
*874The Workers’ Compensation Court, the Honorable Terry Pendell, Judge, awarded benefits, finding that the Claimant's response to the emergency call was a special mission for the employer, and that the injury arose out of and in the course of employment. A three-judge panel vacated a portion of the award pertaining to the Claimant’s back, but in all other respects sustained the trial courts’ award as neither contrary to the law nor against the weight of the evidence. The Hospital appealed, arguing that the worker was simply returning to work, and that injuries sustained going to and from the workplace are not compensable. The Court of Appeals agreed with Hospital and vacated the award. We have granted certiorari.
For an injury to be compensable under the Workers’ Compensation Act it must “arise out of’ and be “in the course of’ employment. 85 O.S.Supp.1993 § 11. Whether an injury arises out of and in the course of employment is an issue of fact to be determined by the Workers’ Compensation Court, and such a finding is not to be disturbed on appellate review “where there is any competent evidence to support the order subject to review.” Stiles v. Okla. Tax Comm’n, 752 P.2d 800, 802 (Okla.1987) (emphasis in original). Title 85 O.S.1991 § 26(B) provides that “The decision of the Workers’ Compensation Court shall be final as to all questions of fact_” Only in the absence of support in competent evidence may a trial court’s decision be found erroneous as a matter of law on review. Parks v. Norman Municipal Hospital, 684 P.2d 548, 552 (Okla.1984).
The clauses “arise out of’ and “in the course of’ are not interchangeable. The former contemplates a causal relationship between the act being done at the time of injury and the requirements of employment, while the latter relates to the time, place, or circumstances under which the injury occurs. Fudge v. University of Oklahoma, 673 P.2d 149,150 (Okla.1983).
Hospital is correct that as a general rule an injury sustained while going to or from an employer’s premises is not one arising out of and in the course of employment within the meaning of the Act. Christian v. Nicor Drilling Co., 653 P.2d 185, 186 (Okla.1982). There are exceptions to this doctrine, as we pointed out in Fluor Engineers & Contr. Inc. v. Kessler, 561 P.2d 72, 74 (Okla. 1977):(1) if the employer furnishes the transportation or pays travel expenses, (2) if the employee is assigned a special task outside regular working hours, or (3) if the injury occurs on premises owned or controlled by the employer. Awards have also been sustained where the employee, on his way to or from work, is still charged with some duty in connection with employment, Novak v. McAl-ister, 301 P.2d 234, 235 (Okla.1956), and when the employee is engaged in a dual purpose trip. F.W.A Drilling Co. v. Ulery, 512 P.2d 192,194 (Okla.1973).
Today’s case turns on whether the “special task” exception applies. The trial court found that it did, and the appellate court found that it did not. Here is what Professor Larson says about the special mission or special task rule:
When an employee, having identifiable time and space limits on his employment, makes an off-premises journey which would normally not be covered under the usual going and coming rule, the journey may be brought within the course of employment by the fact that the trouble and time of making the journey, or the special inconvenience, hazard, or urgency of making it in the particular circumstances, is itself sufficiently substantial to be viewed as an integral part of the service itself.
1 Larson, The Law of Workmens’ Compensar tion, § 16.10.
Whether the claimant is engaged in a special mission for his employer is a question of fact to be determined by the trial tribunal. Hospital argued, and the Court of Appeals concluded, that even if the injury occurred “in the course of’ employment (Mooney was on his way to render emergency room work at demand of employer), it did not “arise out of’ employment, because the risks of driving to the hospital at that particular time were no greater than the risks all the public took in driving that route. This argument misses the point.
In City of Edmond v. Monday, 910 P.2d 980 (Okla.1995), there was evidence to sup*875port the trial courts’ finding that claimant broke away from a personal errand to cheek the employer’s mail. In crossing the street she fell on a curb and broke her hip. Although she was at no more risk than any other pedestrian crossing the street we sustained the award; there was evidence that she was about her employer’s business.
In Fudge, supra, there was no evidence to support an order denying compensation where the employee had to cross a busy street to reach her car in an employer-owned parking lot. Although she was at no more risk than the rest of the public who crossed that street, we directed an award; the employer chose to place its parking lot for employees in that position.
In other words, once it is determined that the employee is doing the employer’s work, e.g., is on a special mission, it does not avail the employer to say the risks of injury to the employee are no greater than the risks to the general public. On this special mission the Claimant’s task, his job, was to promptly drive to the emergency room for an emergency. Getting there to accommodate his employer was what he was told to do and what he attempted to do. Similar is the case of a truck driver hired to drive from one destination to another, where the truck driver is exposed to no more risk than the general motoring public, but because his mission is employment related it follows that an injury resulting from those risks is causally connected to the employment. Por a discussion of employment — related risk see American Management Systems, Inc. v. Burns, 903 P.2d 288, 91, 292 (Okla.1995).
In our case there was evidence before the trial court that the Claimant had certain working hours with a normal one hour break for lunch. Some fifteen minutes into that break Hospital interrupted his lunch with a call that he return immediately for an emergency procedure. In obeying that directive Claimant was injured. On this record it could be found that Claimant’s return trip was “outside regular working hours”, and within the “special mission” exception. See Fluor Engineers, supra; Larson, supra.
The order of the trial court finding the injury to have arisen out of and in the course of his employment is thus supported by competent evidence. Whether he was engaged in a special mission for the employer when injured was a question of fact to be determined by that court. City of Edmond, supra. The opinion of the Court of Appeals is vacated. The order of the Three-Judge Panel of the Workers’ Compensation Court is sustained.
ALMA WILSON, C.J., KAUGER, V.C.J., and HODGES, LAVENDER, HARGRAVE and WATT, JJ., concur. SIMMS, J., concurs in judgment. OP ALA, J., concurs in result but not in the court’s opinion.