What You Need To Know About Core Body Temperature – FAQ

What is Core Body Temperature (CBT) and why is it essential for me to track the CBT levels of my employees? This FAQ provides the answers to keep your workforce safe from record climatic temperatures this summer.

What is CBT?

Measuring a person’s CBT is a means of protecting them from heat-related illness (HRI). This is especially important for employers with staff working in heat-intensive environments where, currently in the UK, there is no law for maximum working temperature , or when it’s too hot to work. These environments could be outdoor – such as construction sites and utility plants, or indoor/enclosed – such as factories and underground mines. In some working environments where staff are working in direct heat constantly, such as metal foundries, the risk of HRI is even greater.

Heat stress can have damaging consequences on a person’s health, and in worst cases, lead to death. This is because working in excessive heat leads to an increase in blood flow to move blood from the core to the skin to help dissipate heat and regulate the CBT, also known as thermoregulation. This process is taxing on the cardiovascular system – meaning the heart needs to pump harder and faster. Excessive heat stress can also impair the function of some cells in the body which can lead to the failure of other organs.

While humans can adapt to warmer environments over time through acclimatisation, the risk of cardiac injury is greater in heat-intensive environments where the stress on the body is greater. It also means that newer recruits who might not be used to working in heat-intensive environments have an even greater risk of cardiac injury, and so too those at a later stage of their career due to the body’s thermoregulatory and cardiovascular systems becoming less efficient with ageing.

How do I measure CBT?

Heat stress can be managed effectively by capturing a reliable proxy of CBT of individuals at work, also known as individual monitoring – as opposed to measuring the environments in which they’re working, also known as ambient monitoring. Ambient monitoring is the least effective way of monitoring heat stress as each person has a different physiological response to challenging environments. Another common misconception is that monitoring temperature through the skin will provide an accurate indication of a person’s CBT; however, skin temperature is only a measurement of the body’s surface temperature and is not directly related to CBT. In addition, skin temperature can be affected by variables including environmental conditions, the level of physical exertion of an individual and the amount of protective clothing worn, so will not provide a reliable analysis of CBT.

A recognised and generally reliable and practical method of measuring CBT is swallowing a telemetric gastrointestinal (GI) temperature pill. This is an ingestible pill that looks like any other drug capsule but acts as a wireless thermometer. As it moves down the GI tract, the pill wirelessly sends data to a handheld device to provide a raw output of a person’s CBT levels.

In research laboratories, the GI pill is a considered a benchmark of CBT, but due to its high cost and single use, it is not practical or scalable for use in a field environment. However, advancements in wearable technology mean the GI pill is no longer the only accurate means of measuring CBT. For example, Bodytrak® captures real-time physiological data using in-ear sensors, analysed by AI on the device and in the cloud to provide critical insights into a person’s CBT levels. Recent data from a lab-based study comparing Bodytrak with the GI pill showed a strong positive correlation of 0.88, which is classified as a very strong relationship, highlighting its effectiveness in measuring CBT.

How can I measure the CBT of my employees?

The only way to reliably measure the CBT of your employees in the field is by investing in an accurate solution. At Bodytrak, we protect workers from incidents caused by heat stress and fatigue with highly accurate in-ear sensors and a cloud-based data-analytics platform, enabling intervention through our incident management dashboard and user alerts.