delivered the opinion of the court:
On April 6, 1988, decedent, Carol Pellegrino, fell down a flight of stairs while working in a building in which the appellant, William G. Ceas and Company (the employer), was a tenant. As a result of the fall, she suffered a subdural hematoma and died on April 12, 1988. Her surviving spouse, Robert Pellegrino, and youngest son, Douglas Pellegrino (the claimants), sought death benefits pursuant to section 7(a) of the Workers’ Compensation Act (Ill. Rev. Stat. 1987, ch. 48, par. 138.7(a)). The arbitrator awarded benefits to claimants in the amount of $236 per week to Robert Pellegrino and for the benefit of Douglas Pellegrino, son of decedent, for as long as he remained a full-time student and had not attained the age of 25. Burial expenses were awarded in the statutory amount of $1,750; medical expenses of $20,111 were also awarded. Both parties took a review of the arbitrator’s decision to the Industrial Commission (Commission). The Commission, in an order dated June 14, 1991, affirmed the decision of the arbitrator. The circuit court confirmed the Commission’s decision, and the employer now appeals to this court. On March 19, 1993, an opinion was filed by this court reversing the decision of the circuit court. Subsequently, claimants filed a petition for rehearing. The petition for rehearing was granted, and the opinion was withdrawn. After reviewing the entire matter, a majority of this court has reached the conclusion that the Commission’s decision should be affirmed.
At this point, we note that the dissent gives a lengthy recounting of the case’s procedural history. Admittedly, it is one filled with twists and turns. It appears that the dissent views this as reflective of an arbitrary and capricious approach to the case before us. Our perspective is that this has been an exceedingly difficult case, in which the majority has conscientiously endeavored to achieve a just result.
*632The following evidence was adduced at the arbitration hearing. We take exception to the dissent’s implication that the following presentation of the facts gives a distorted presentation of the evidence.
Decedent was employed as a secretary by Ceas Mortgage Company. This company was on the second floor of an office building, along with Ceas Development and William G. Ceas and Company. A single oak staircase led up to the second floor. The building had no elevator. The stairway was the only way to get to and from the second floor and was used by employees of Ceas Mortgage Company, Ceas Development, and William G. Ceas and Company.
Part of decedent’s duties included putting Federal Express envelopes into the Federal Express box at the end of the day. On April 6, 1988, another secretary, Nancy Horcher, noticed that decedent was in a hurry at the end of the day. Horcher testified that decedent had been running back and forth to get something finished before she left. Horcher heard a noise soon after decedent left the office. Horcher then looked out an interior window and saw that decedent had-fallen at the bottom of the stairs. Horcher went to get help from the company comptroller, Kreil Greiter. On cross-examination, she noted that decedent sometimes drank alcoholic beverages during the work day. Horcher sometimes detected alcohol on decedent’s breath when passing her at work. She did notice that decedent had been drinking on April 6, 1988.
Virginia Griffith, an employee of another tenant of the building, Fiordalis Associates, testified that at 5 p.m. on April 6, 1988, she had locked up her office to go to the washroom. Upon exiting the washroom, Griffith noticed a woman sprawled out on the floor at the bottom of the stairway. It is undisputed that this woman was decedent. Decedent was bald-headed; a wig lay off to her side. Griffith asked if she could help decedent, who appeared to be nervous and in a great hurry. Decedent said she had to get to the Federal Express box and then get home. About this time, a man from upstairs (Kreil Greiter) came down to offer assistance. Decedent did not say how she had fallen.
Bystanders helped her up, and she rested a few moments. Griffith noticed a gash with dried blood around it on the back of the decedent’s head. She refused any medical assistance, namely, calling an ambulance. Decedent put the wig back on her head and left in the direction of the Federal Express box and, subsequently, drove out of the building’s parking lot.
On cross-examination, Griffith stated that packages had to be in the Federal Express box at either 5 or 5:30 p.m. for the next day’s delivery. Griffith thought she smelled the odor of alcohol on *633decedent’s breath; however, she did not think that decedent was under the influence of alcohol.
Greiter testified that he was the employer’s comptroller. On the subject date at about 5 p.m., he opened the office door and saw decedent lying at the bottom of the steps, where Griffith was attending to her. Greiter went down the stairs to see if he could help. Decedent seemed disoriented. He said that he would call an ambulance, but she refused any medical assistance. Greiter helped get her on her feet. He noticed several Federal Express envelopes in her purse. Greiter also observed a lump on the back of her head. Greiter stated that he was aware of instances in which decedent had been drinking at work. Greiter did not smell alcohol on decedent’s breath on the subject date.
On cross-examination, Greiter stated that he noticed nothing unusual about the stairs on the subject date. He reiterated that decedent was in a hurry; he did not see her go to the Federal Express box. At about 4:30 p.m. on the day in question, Greiter recalled seeing decedent moving quickly from the typewriter to the printer.
Claimant Robert Pellegrino testified that he had been married to decedent since April 14, 1956. After work on the date in question, claimant noticed that decedent was very upset. He noticed that she had bruises on her body and a bump on the back of her head. Decedent told the claimant that she had fallen at work. She told him that she was very upset about the fall and about her boss’ habit of giving her things to do at quitting time. Claimant stated that decedent arrived home at the usual time, about 5:50 p.m.
On April 8, decedent began to complain that she felt like she was coming down with the flu. The following day, she was getting progressively worse and decided to lie down on the couch. When claimant could not awaken her, he summoned paramedics. Decedent was taken to Humana Hospital, where she died on April 12, 1988. The cause of death was listed as fontotemporal epidural hematoma. Experts for both claimant and the employer agreed that the fall was the cause of decedent’s death.
Previously, decedent had suffered from breast cancer and had undergone a mastectomy of the left breast. At the time of her death, she was found to have advanced cancer of the breast with metastases to the brain and rib. Decedent had received chemotherapy and radiation treatment for her cancer. Claimant testified that decedent had completed her radiation therapy approximately one month before the date of the accident. Decedent had been taking the drug Coumadin as an anticoagulant and was also taking Nolvadex, an anti-estrogen breast cancer treatment.
*634Claimant testified that decedent drank alcohol socially, but was unaware of any instances in which she drank at work. Claimant did not notice alcohol on decedent’s breath on April 6, 1988.
Kim Ash, a manager in the employer’s executive office, testified that she noticed several incidents when decedent would be drinking around lunch time. Ash noticed the smell of alcohol on decedent several times a week. She did not notice such a smell of alcohol on decedent’s breath on the subject day. Ash also testified that the last pick-up time on the Federal Express box outside the building had always been 6 p.m. None of the witnesses testified that they noticed the smell of alcohol on April 6, 1988, and Virginia Griffith stated that she did not believe decedent was under the influence of alcohol.
Dr. William Barnhart, testifying for the employer, opined that decedent’s fall could have been a sequence of events which were the result of decedent being on Nolvadex, having been weakened from chemotherapy, and having metastatic cancer into the brain. Barn-hart admitted that he could find nothing in the medical record to indicate that decedent was, in fact, weakened by cancer. He also stated that he used the word "potential” because he could not tell from the records whether decedent was suffering any side effects from the medicine.
Dr. Nathaniel Greenberg testified for claimant. In Dr. Green-berg’s opinion, the fall was not due to either medication or brain metastases. He did state, though, that it was possible that a person could suffer dizziness from chemotherapy and that it was possible that the brain metastases could cause dizziness.
On appeal, the employer argues that the Commission erred in finding that this was an unexplained fall. In support, the employer argues that the Commission erroneously rejected the idiopathic nature of decedent’s fall. Claimant argues that the fall was unexplained, rather than idiopathic. Idiopathic falls result from internal, personal origins, while unexplained falls result from neutral origins. (Oldham v. Industrial Comm’n (1985), 139 Ill. App. 3d 594, 487 N.E.2d 693.) Illinois denies compensation for idiopathic falls (Elliot v. Industrial Comm’n (1987), 153 Ill. App. 3d 238, 505 N.E.2d 1062), but awards compensation for unexplained falls. Chicago Tribune Co. v. Industrial Comm’n (1985), 136 Ill. App. 3d 260, 483 N.E.2d 327.
The employer suggests that this issue should be reviewed as erroneous as a matter of law. The employer cites Caterpillar Tractor Co. v. Industrial Comm’n (1989), 129 Ill. 2d 52, 541 N.E.2d 665, for the proposition that when undisputed facts are susceptible to a single reasonable inference the issue presented to the court on review becomes a question of law. Claimant agrees with this proposition, but *635points out that the facts in this case are susceptible to more than one inference. If more than one inference may be drawn from the undisputed facts on any issue, the determination of such issues is a question of fact, and the conclusion of the Commission will not be disturbed on review unless it is contrary to the manifest weight of the evidence. (Caterpillar, 129 Ill. 2d 52, 541 N.E.2d 665.) We agree with claimant. From the undisputed facts of this case, one could conclude either that decedent suffered an idiopathic fall or an unexplained fall. Therefore, this issue should be reviewed under the manifest weight of the evidence standard.
The finding of the Commission that this was an unexplained fall was not contrary to the manifest weight of the evidence. The employer’s expert witness, Dr. Barnhart, testified that in his opinion decedent’s cancer-related condition caused her fall. Dr. Barnhart admitted that he could not find evidence in the medical record that decedent was in a weakened condition or that she was suffering any side effects from medication. Also, other employees of the William Ceas Company testified that decedent was functioning normally, had not had any dizzy spells, nor had she had any other falls at work. It was for the Commission to determine whether or not the fall was unexplained, and the Commission’s decision was clearly not against the manifest weight of the evidence.
The employer also argues that the finding of the Commission that the fall occurred on the employer’s premises was against the manifest weight of the evidence. Illinois Bell Telephone Co. v. Industrial Comm’n (1989), 131 Ill. 2d 478, 546 N.E.2d 603, was cited for the proposition that injuries sustained by an employee leaving from work in the common areas of a building are not compensable. Claimant argues that Illinois Bell is not applicable because the employer in that case was a tenant occupying an office on the second floor of a shopping mall complex. The employer in that case had no interest in the common areas of the building. There were many different mall entrances, and employees were not expected to use any particular route to get to the employer’s premises. In the instant case, William Ceas Company, Ceas Development, and Ceas Mortgage Company occupied the entire second floor of the building. The stairway in question was the only way for employees to get to work. The only people who used the stairway were Ceas employees and Ceas customers. Therefore, claimant argues that this is an entirely different situation than in Illinois Bell. Claimant asserts that we should follow the decision in Master Leakfinding Co. v. Industrial Comm’n (1977), 67 Ill. 2d 517, 367 N.E.2d 1308. In that case, claimant suffered a fall on the back stairs of a building the employer shared *636with an architectural firm with which it was engaged in a joint venture. The Commission in that case believed the stairs to be a part of the employer’s premises. The Commission’s award was reinstated by the supreme court.
We find that the circuit court and Commission were correct in deciding that the stairway in this case was on the employer’s premises. The circuit court noted the intertwined nature of the Ceas companies and that the stairway was the only means to get to and from the second floor. This would make the instant case more similar to Master Leakfinding than to Illinois Bell.
Further, the employer argues that the finding of the Commission that the accident arose out of decedent’s employment is erroneous as a matter of law and contrary to the manifest weight of the evidence. For an employee’s injuries to be compensable, those injuries must arise out of and in the course of his or her employment, and both elements must be present at the time of the accident to justify compensation. (Hatfill v. Industrial Comm’n (1990), 202 Ill. App. 3d 547, 560 N.E.2d 369.) "Arising out of’ refers to the origin or cause of the accident and presupposes a causal connection between employment and the accidental injury; "in the course of’ refers to the time, place and circumstances under which the accident occurred. Illinois Bell, 131 Ill. 2d 478, 546 N.E.2d 603.
It is the Commission’s province to determine the credibility of the witnesses and to determine causal connection between a claimant’s condition of ill being and her employment. (BMS Catastrophe v. Industrial Comm’n (1993), 245 Ill. App. 3d 359, 365.) The question of whether an injury is causally connected to a person’s employment is to be determined by the Commission, and its decision will not be set aside unless it is against the manifest weight of the evidence. (Williams v. Industrial Comm’n (1993), 244 Ill. App. 3d 204.) A reviewing court will not reject reasonable inferences made by the Commission merely because the court might have drawn contrary inferences on the same facts. Archer Daniels Midland Co. v. Industrial Comm’n (1990), 138 Ill. 2d 107.
Claimant testified that, after the subject fall, decedent had told him about her anger with the boss’ habit of giving her things to do right before quitting time. Nancy Horcher stated that, right before the fall, decedent had been running back and forth to finish something before she left. Kreil Greiter also saw decedent hurriedly moving from her "typewriter” to the printer immediately prior to quitting time. Subsequently, Horcher heard the noise of decedent falling down the stairs. Virginia Griffith testified that she came upon decedent sprawled on the floor. Griffith sought to help decedent, who *637stated that she had to get to the Federal Express box. Decedent appeared nervous and in a great hurry. Greiter, who came from upstairs, assisted Griffith in getting decedent to her feet. Greiter and Griffith offered to assist decedent in obtaining medical help. Decedent declined, stating that she had to get to the Federal Express box to mail envelopes. Greiter observed several Federal Express envelopes in decedent’s hands. There was no indication that the Federal Express envelopes were anything but the employer’s business, and after she got up from the fall, she took a right turn to the Federal Express box. The evidence as to when envelopes had to be delivered to the Federal Express box to ensure next day delivery was conflicting. Also, the record does not indicate that decedent was going anywhere but home, after first dropping off the envelopes in the Federal Express box.
From these facts, the Commission could have inferred the following. At the end of a workday, decedent had been told by her boss to prepare and mail a number of Federal Express envelopes. It was typical of the boss to make this type of last-minute demand of decedent. Decedent rushed to prepare the employer’s envelopes. She then hurriedly left the office. Her immediate destination was the Federal Express box located on the premises where she would mail the envelopes. In the process of quickly going down the stairs, decedent lost her footing, fell down the stairs and incurred the fatal injury. But for the employer’s habit of requiring last-minute preparation and mailing of Federal Express envelopes and the resulting stress that it placed on decedent, there would have been no fatal fall.
Given these permissible inferences, claimant proved that the risk of this type of injury to decedent was increased as a consequence of her work. Orsini v. Industrial Comm’n (1987), 117 Ill. 2d 38, 509 N.E.2d 1005.
The dissent asserts that the majority opinion classifies claimant’s fall as employment related and omits testimony that undermines that finding. The evidence, however, clearly supports the Commission’s reasonable inference that claimant’s fall occurred while she was in the process of going to the Federal Express box to mail envelopes transmitting business of the employer. As pointed out in this opinion, the Commission found that the claimant was in the course of her employment at the time of the fall. This was a reasonable inference the Commission could make from the facts. The dissent seeks to avoid this finding by stating that as a matter of law claimant’s fall did not arise out of her employment. Nevertheless, claimant was on the way to deposit mail in the Federal Express box, and she was in a hurry because of the fact that her employer was *638loading her with duties close to the time her employment for the day had ended, namely, at 5 p.m. The foregoing facts support the finding of the Commission, and such a finding was not contrary to the manifest weight of the evidence.
Accordingly, the Commission’s decision that decedent’s accident arose out of and in the course of her employment is not against the manifest weight of the evidence.
The judgment of the circuit court is affirmed.
Affirmed.
RAKOWSKI and RARICK, JJ., concur.