Understanding Humidex: A Comprehensive Guide

Discover how humidex can help companies ensure operational safety and improve productivity, and the best practices for implementing it in the workplace.

worker using a humidex software

What is Humidex?

Humidex (humidity index) is an index that represents how hot the weather feels to an individual by combining the effects of temperature and humidity. First used by Canadian meteorologists in the 1960s, this index has become a vital parameter across industries because it gives a more accurate sense of heat stress on the human body. It also helps organizations make better decisions about work conditions, outdoor activities, and indoor work environments.


Heat stress, a condition wherein the body cannot eliminate excess heat, is problematic and should be prevented in the workplace. Employees suffering from this can get physically impaired, reducing their productivity and increasing their risk of accidents and injuries.

Following this reason, maintaining optimal environmental conditions within facilities and workspaces should be the organization’s top safety-related priorities. Utilizing humidex can help health and safety supervisors implement protocols to prevent heat-related illnesses and incidents, guide operational managers in scheduling tasks and activities during hot weather, and assist compliance teams in upholding health and safety regulations.

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Humidex: An Overview

To effectively utilize humidex, relevant personnel should first understand its mechanics, such as  how it works, how to calculate the values, and how to interpret those numbers. Here is a quick breakdown:

What Does Humidex Measure?

Similar to the heat index of the United States, humidex measures both air temperature and humidity. High humidity levels can make temperatures feel hotter because moisture in the air prevents the body from cooling itself through sweating.  By considering both metrics, a more accurate measure of comfort can be taken.

How to Calculate Humidex?

The main difference between humidex vs heat index is that the former uses dew point in the calculation while the latter takes Relative Humidity (RH):

Humidex = Air temperature in Celsius + 0.5555 x (e -10)


e = 6.11 x exp [5417.7530 x (1/273.15 – 1/ dew point in Kelvin + 273.16)]

Another formula was created using RH:

Humidex – Air temperature in Celsius + 0.5555 (e – 10)


e = 6.11 x exp [5417.7530 (1/273.16 – 1/Air temperature in Celsius +273.16)]

How to Interpret Values?

The results computed range from less than 15 to over 54. These are the general guidelines of the Canadian Center for Occupational Health and Safety (CCOHS):

  • Less than 15 – The air is comfortable. There is little to no perceived discomfort.
  • 15 to 29 – The air is somewhat uncomfortable. However, significant discomfort is not felt.
  • 30 to 39 – Noticeable discomfort is felt and caution is advised.
  • 40 to 45 – There is significant discomfort. Strenuous activities must be avoided.
  • 46 and above – Dangerous levels are reached. There is a risk for heat stroke so severe precautions must be taken.

Government meteorologists work on these calculations and send the results to the media for information dissemination. However, many companies monitor the environmental conditions in their sites to obtain more accurate readings, helping them make better decisions and respond to incidents promptly.

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Practical Applications

Organizations across different sectors and industries use temperature and humidity sensors in their workplaces to determine humidex in real time. Aside from upholding occupational health and safety, they gain several other benefits as well.

Measuring humidex benefits different industries as follows:

  • Manufacturing – Many processes in this industry are heat-intensive, emphasizing the importance of measuring humidex. Aside from worker safety, too high humidex can alsonegatively affect equipment and products.
  • Construction – Workers in this sector are exposed to high temperatures and humidity daily. With this index, managers can re-schedule work at later hours, implement mandatory breaks, and provide the right cooling Personal Protective Equipment (PPEs).
  • Agriculture – Extreme weather conditions can adversely affect livestock and crop management. By assessing various indicators affecting humidex, farmers and agronomists can minimize damage to their farms.
  • Healthcare – Children, senior citizens, and individuals with chronic conditions are more at risk from heat illnesses. With the help of humidex statistics, they can prepare for emergencies and protect the vulnerable population.
  • Sports and Recreation – Because thousands flock to tournaments and concerts, event organizers should utilize humidex. When the readings get too high, they can add shaded areas and set up cooling stations in the venue, as well as make the necessary adjustments to any program currently happening.

Implementing Humidex

Organizations intending to take humidex readings in their sites and facilities should do so as soon as possible. Here is a series of steps that health and safety teams can follow to gain long-term benefits:

Step 1: Assess the Need for Humidex and Plan the Approach

The first step is understanding local climate conditions through evaluating historical climate data. If the company sees the need for humidex, top leaders should define the objectives and develop strategies targeting these goals.

Step 2: Select Tools and Technologies

Investing in the right sensor is a must to ensure accurate humidity and temperature readings. The IoT device must be linked with high-quality software and data integration platforms, since these can provide real-time calculation and data analysis. Ideally, the software used for this has a secure cloud storage built-in, making data easily accessible anytime and anywhere.

Step 3: Collect, Analyze, and Share Data

Gathering, processing, and sorting information in an organized manner is vital in making decisions about daily operations and, consequently, worker safety. Aside from setting up real-time monitoring tools, incorporating alert systems is imperative. This system can be configured to send notifications when predefined thresholds are reached, prompting immediate action.

The most important part of this step is information dissemination. Aside from including humidex and other environmental readings during daily toolbox talks, establishing communication channels (e.g., mobile apps, emails, and public address systems) is crucial.

Step 4: Implement Safety Measures

Developing and enforcing safety protocols is the most important phase in the process because it specifies the procedures to prevent and manage heat-related conditions. Here are just a few to consider:

  • Adjust work schedules to avoid peak heat periods.
  • Distribute workloads to employees to minimize heat exposure.
  • Include 10 to 15-minute heat breaks every work hour if delaying or postponing the project is impossible.
  • Provide breathable clothing and cooling vests in the PPE set.
  • Set up shaded areas and hydration stations, especially in remote areas.

Step 5: Review for Continuous Improvements

Ensure the system remains effective and up-to-date by conducting regular performance reviews and implementing feedback mechanisms for employees and other stakeholders. Aside from updating the protocols, refresh training programs based on environmental changes, new technologies, and the latest research.

Eunice Arcilla Caburao
Article by

Eunice Arcilla Caburao

SafetyCulture Content Contributor
Eunice Caburao is a content contributor for SafetyCulture. A registered nurse, theater stage manager, Ultimate Frisbee athlete, and mother, she has written a wide range of topics for over a decade. Eunice draws upon her rich, multidisciplinary background to create informative articles about emerging topics on health, safety, and workplace efficiency.