The young and new on job most affected by heat stress: Study

Workers who have been on the job for less than two months are at a greater risk of heat strokes, sun strokes and other health-related illnesses, according to a study by the Institute for Work & Health (IWH).

Young men working in manual occupations are most vulnerable to extreme heat. The more inexperienced they are on the job, the more likely they are to need time off work to recover from heat stroke, sun stroke, fainting and other forms of heat illnesses, found the study.

These heightened risks are seen even after accounting for the fact that this group of workers — young, manual labourers new to the job — are already at greater risk of work injury, said Melanie Fortune, a research associate at Toronto-based IWH and the lead researcher of the study on heat stress.

For example, manual workers accounted for 52 per cent of all lost-time claims, but they accounted for 59 per cent of all heat-related lost-time claims. Likewise, workers who were less than one month on the job accounted for 4.2 per cent of all lost-time claims. But their heat-related illnesses accounted for nearly twice that proportion, which was 8.2 per cent of all heat-related lost-time claims, found the study.

Looking at job tenure, the study found that workers on the job from one to two months accounted for 5.9 per cent of all lost-time claims, but nine per cent of all heat-related lost-time claims.

“That matches what we know about the importance of workers being acclimatized to their work environments,” said Fortune. Someone working actively in 32-degree Celsius temperatures, for example, wouldn’t feel the heat effects as severely after two weeks as on the first day.

“But, for new workers who come into heated environments or labour conditions to which they’re not acclimatized, we expect that they’d be more at risk."

The study, the first of its kind in Canada, was a descriptive study with the main objective of painting a portrait of work-related heat stress in Ontario: how often it happens, who faces the most risk and when cases happen most frequently.

The study was carried out using two sets of population-based data. One was hospital emergency room (ER) records where the visit was recorded as work-related. The other was lost-time claims across Ontario for the period of 2004 to 2010, obtained from the Workplace Safety and Insurance Board.

In the seven years covered by the study, emergency rooms in Ontario treated 785 cases of heat illnesses incurred at work. During that time, workers filed 612 lost-time claims for heat illnesses. The monthly incidence rates of heat illness were 1.6 per 1,000,000 workers according to ER records, and 1.7 per 1,000,000 workers according to claims data.
One of the more notable findings in the study was the fact that the illnesses tended to occur in clusters. The ER visits and lost-time illnesses occurred on just 12 per cent of all days during the seven-year period.

More than half (55 per cent) occurred during groups of more than one day. One particularly hot spell over two days in August 2006 accounted for 101 instances (or 13 per cent) of all heat-related ER visits in the seven years.

“We know from other research that after a heat exposure, our bodies really need time to recover,” said Fortune. “Let’s say we have a string of hot days, and you don’t have air conditioning at home and you drink a beer after work to cool down, your body may not have recovered when you go back into work the next day."

Risk levels by sector

The report also looked at sectors with the highest risk of heat stress. Workers in government services accounted for 14.6 per cent of all heat illnesses, which was 2.3 times higher than their share of 6.3 per cent of all injuries. That ratio — of 2.3 for government workers — was the highest of all the sectors. Agriculture had the second highest (1.9), followed by construction and business service, both at 1.4.

The sectors highest on the list were those with a lot of outdoor work. Government services included workers who maintained parks, fought forest fires and collected trash.

The study can be found here: At Work, Issue 73, Summer 2013: Institute for Work & Health.