Heat rules in Nova Scotia: ACGIH values under the Workplace Health and Safety Regulations
What the Nova Scotia Workplace Health and Safety Regulations say about threshold limit values for physical agents, and how the Department of Labour's Heat Stress Guidelines of July 2020 apply them with WBGT screening values.
Checked against the sources at the bottom of this page on October 9, 2026. Rules, fees and pay change: the source has the last word.
This page reports what the official source says. It is not legal advice: ask the office named here. It restates Part 2 of the Workplace Health and Safety Regulations under the Occupational Health and Safety Act (the province's unofficial consolidation, which states it is for reference only), the Hazard Alert Heat Stress Guidelines of July 2020, the Safety Branch's Heat Stress safety bulletin and the Canadian Centre for Occupational Health and Safety (CCOHS) summary of provincial temperature rules, all read on October 9, 2026. The comparison of every place is on the heat rules overview.
What the regulation says
Section 2.1 defines "physical agent" as an agent of acoustic, electromagnetic, ergonomic, mechanical or thermal nature, and "threshold limit values" as those in the American Conference of Governmental Industrial Hygienists (ACGIH) publication of threshold limit values and biological exposure indices, in whichever version has been issued last. Section 2.3 puts a duty on the employer to meet those values for gases, vapours, mists, fumes, smoke, dust, chemical substances and physical agents, as the publication lists them. Section 2.2 says Part 2 prevails over any conflicting provision of the regulations or of other regulations made under the Act. CCOHS lists the same sections 2.1 and 2.3 for heat and cold.
What the Department's guidelines add
The Heat Stress Guidelines tie the duty to two provisions: the employer's duty under clause 13(1) of the Act to take every reasonable precaution to ensure health and safety, and the regulation's threshold limit values, since heat stress is covered as a physical agent. They say the Wet Bulb Globe Temperature (WBGT) index adopted by ACGIH is the regulatory criterion for environmental heat. They give two equations: with no solar load, 0.7 of natural wet-bulb temperature plus 0.3 of globe temperature; outdoors with solar load, 0.7 of natural wet-bulb plus 0.2 of globe plus 0.1 of dry-bulb. The measured value is adjusted for clothing, then compared with Table 4.
| Work demand | WBGT in degrees Celsius for 75 to 100, 50 to 75, 25 to 50 and 0 to 25 percent of the hour worked |
|---|---|
| Light | 31.0, 31.0, 32.0, 32.5 |
| Moderate | 28.0, 29.0, 30.0, 31.5 |
| Heavy | no value, 27.5, 29.0, 30.5 |
| Very heavy | no value, no value, 28.0, 30.0 |
The guidelines add clothing adjustments to the measured WBGT in degrees Celsius: 0.0 for work clothes or woven cloth coveralls, 3.0 for double-layer cloth clothing, 0.5 for polypropylene coveralls, 1.0 for polyolefin coveralls and 11.0 for limited-use vapor-barrier coveralls, with a note that these must not be used for fully encapsulating suits and cannot be added for multiple layers. They state that the values assume acclimatized, fully clothed workers with adequate water and salt intake who should not exceed a deep body temperature of 38 degrees Celsius. If the adjusted WBGT exceeds the screening value, the guidelines say physiological monitoring must be conducted, and list a sustained heart rate above 180 beats per minute minus age, a core body temperature above 38.5 degrees (38 for unselected, unacclimatized workers), or a recovery heart rate above 120 beats per minute one minute after peak effort as strain indicators.
The Safety Branch bulletin
The Safety Branch's Heat Stress bulletin says the employer must develop a heat stress strategy with three parts: training and education, a heat stress assessment, and heat stress controls. It lists the assessment as an initial environmental assessment, WBGT monitoring, clothing adjustment and work demand analysis. The pages read do not give a separate Nova Scotia rule for work outdoors in trees.
Sources
- Nova Scotia Department of Justice, Workplace Health and Safety Regulations, unofficial consolidation, Part 2, read October 9, 2026
- Nova Scotia Department of Labour and Advanced Education, Hazard Alert: Heat Stress Guidelines, July 2020, read October 9, 2026
- Nova Scotia Department of Labour and Advanced Education, Safety Bulletin Number 0000001: Heat stress, read October 9, 2026
- Canadian Centre for Occupational Health and Safety, Temperature conditions: legislation, read October 9, 2026