Does a Worker Who Suffers a Heart Attack at Work Have a Compensable Claim?


While working in a large freight container, a worker says he feels ill and begins walking to the first aid station. But he collapses and has a heart attack. The worker files a workers’ comp claim, arguing that his heart attack was caused by the hot temperature and lack of ventilation in the container. His treating physician at the hospital confirms that he suffered an acute coronary event. The doctor notes that the worker’s risk factors for coronary artery disease including his hypertension, prior smoking habit and family history for heart disease were the likely causes of the coronary event, but says that a heart attack can also be caused by excessive strain due to physical activity and extreme heat. The employer denies that the container was excessively hot: the large doors to the container were open for ventilation, a fan was provided and the highest temperature recorded the day of the incident was 17°C. The workers’ comp board rejects the claim, ruling the heart attack wasn’t work related. So the worker appeals.


Is the worker’s heart attack compensable?

A.  Yes, because the worker wasn’t adequately protected from heat stress, a workplace hazard, which caused the acute coronary event.
B.  Yes, because the worker became ill while working.
C.  No, because the heart attack was the result of the worker’s personal health history and medical risk factors.
D.  No, because the worker should’ve refused to work if the conditions were too hot.

C. Because the worker’s family history and other personal risk factors, rather than the work environment, were the likely cause of the heart attack, it isn’t covered by workers’ comp.


This hypothetical is based on a decision by the Appeals Commission for Alberta Workers’ Compensation in which the Commission concluded that the evidence didn’t support a finding that an occupational exposure or stress caused the worker’s heart attack. The Commission agreed that the worker did suffer an acute coronary event, based on the treating physician’s testimony. However, the Commission found the evidence regarding the weather conditions on that day and the environment inside the container didn’t indicate the worker was exposed to extreme heat. Additionally, the medical evidence indicated the worker’s condition was caused by his coronary artery disease and other medical risk factors unrelated to his working conditions. Thus, the illness didn’t arise out of the course of employment and wasn’t compensable, concluded the Commission.


A is wrong because the conditions the worker experienced wouldn’t generally qualify as creating a risk of heat stress. There’s no single temperature threshold above which indicates heat stress. Although the heat stress requirements vary by jurisdiction, they’re usually triggered when “thermal conditions,” which includes both air temperature and humidity, exceed safe levels. And it’s unlikely that a temperature of 17°C would be considered unsafe. In addition, the doors to the container were open and a fan was present to provide additional ventilation. So the facts don’t suggest that the worker was unprotected from heat stress or that excessive heat caused his illness, which would be necessary to support a compensable claim.

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B is wrong because an illness or medical condition isn’t compensable just because it happened at work. The illness or condition must arise out of and occur in the course of employment. For example, an illness arises out of employment when it’s caused by a workplace hazard and occurs in the course of performing work duties. Here, the worker’s heart attack did occur while he was working but there’s no evidence a workplace hazard caused it. Rather, the evidence indicates personal health issues were the more likely cause of the heart attack. Thus, it isn’t covered by workers’ comp.

D is wrong because although a worker has the right to refuse work if he has a reasonable belief the work involves a danger to himself or other workers, failing to exercise that right doesn’t bar him from bringing a worker’s comp claim for an injury or illness caused by the allegedly unsafe work. If a worker truly believes that he’s being exposed to a workplace hazard, such as heat stress, he should exercise his right to refuse before he gets injured or ill performing that work. But he’s not required to do so. And if he should get injured or sick due to the work, he’s entitled to workers’ comp. Here, if the worker truly believed he was exposed to the risk of heat stress in the container, he could’ve exercised his right to refuse. But the fact that he didn’t do so doesn’t mean he forfeits his right to file a workers’ comp claim for any arguably resulting injury or illness. However, the evidence neither supports a conclusion that the work was, in fact, unsafe nor that the conditions caused or contributed to his heart attack.


Decision No.: 2013-0861, [2013] CanLII 59334 (AB WCAC), Sept. 18, 2013