Unstable temperatures increases risk of heat related death by up to 2900 per cent, study claims

Changes in daily temperatures in warmer months increases the risk of heat-related death, a new study warns.

The study by Monash University found the chance of death increases by an average of 290 percent globally when daily temperatures fluctuate – and this reaches to over 2900 per cent in central Europe.

Researchers from 36 countries used daily temperature and mortality data from 1972 and 2018 carry out the study which was led by Professors Yuming Guo and Shanshan Li from the Monash Climate Air Quality Research (CARE) Unit.

They found that there were more heat-related deaths on days where there were significant temperature changes across a 24-hour period, compared to days when the temperature remained stable.

Professor Guo said: “We are living in a warmer and warmer environment that pervasively affects human life and undermines the years of gains in public health.

“Human-induced warming has been associated with an increase in frequency and intensity of hot days and increasing heat exposure leads to more sickness and death. Meanwhile, temperatures tend to be more and more unstable under climate change.”

He added that there are several ways that both exposure to and fluctuations in heat can impact the body.

Primarily, when exposed to heat, people expend more of their reserves to regulate their core body temperature in response which causes increased heart rate and blood pressure, decreased blood pressure and respiration to lose heat with the expired air.

Furthermore, sudden temperature changes in a short period of time causes some people to experience difficulty in thermoregulation, resulting in inflammatory responses and blood abnormalities induced by heat stress.

For people with underlying health issues, quick changes in temperature can put extra pressure on their bodies and increase risk of heat-related death and in the long-term, sudden temperature changes can also cause cardiovascular and respiratory diseases for people.

In the past two decades, an average of 490,000 people have died every year from heat-related issues globally and Professor Guo added that few studies have examined whether temperature has an impact on heat-related deaths until now.

Increased risk of heat-related mortality due to high daily temperature variations versus low daily temperature variation, by region:

North America - 145%

Central America - 895%

South America - 263%

North Europe - 1382%

Central Europe - 2853%

Southern Europe 516%

Mid East Asia - 126%

East Asia - 163%

South East Asia - 547%

Australia - 95%

Globally - 290%

The study’s authors are calling for urgent action “to raise public awareness of potential health risks of temperature variability”.

“Targeted adaptation strategies against heat-related mortality burden should be implemented after taking the fluctuation of temperatures and geographical patterns into account,” they said.

In response to the increasing heat-related conditions and deaths, heat-health warning systems are being developed around the world – such as the World Health Organisation (WHO) who are developing heat-health action plans (HHAPs) for 35 out of 53 member states of the WHO European Region by the end of 2018.

Professor Guo added: “We observed increased heat-related mortality risks with the increment of temperature variability across countries in Europe where HHAPs are implemented. More detailed and hierarchical warning system should be implemented to cope with increased health risk associated with both heat and fluctuated temperature.”