In the previous post, we looked at a study by Åström and colleagues. The researchers found an excess of mortality in many subpopulations during heatwaves and this included psychiatric subpopulations. There are a number of factors which play a role in how these findings might be interpreted although the authors discuss how this can information can help to prepare for heatwaves. The factors that may play a role include how populations adapt to heatwaves over time, the average temperature (compared to the temperature in a heatwave), the temperature during the heatwave, the humidity, the response of the health economy, the utilisation of health services as well as the structure of the health economy. The other point to consider is that there are different definitions of heatwaves.
Looking at humidity (albeit in relation to cardiovascular mortality), these researchers combined temperature with humidity to create a heat index. They found that
‘females, elderly people, and outdoor workers have higher vulnerability levels in regard to a high heat index’
One UK study found an increased number of mental health related A&E visits together with admissions when looking both at heatwaves and high ambient temperatures. The same authors did not find an increase in utilisation of community mental health services. The authors of this study note that there are current knowledge gaps and that
‘Mental health impacts should be incorporated into plans for the public health response to high temperatures, and as evidence evolves, psychological morbidity and mortality temperature thresholds should be incorporated into hot weather-warning systems‘
One study examined heat associated excess mortality (although distinct from heatwaves) from 1900 to 1948 and 1973 to 2006 in New York City. The researchers found that the excess mortality decreased in the second period. The authors suggested that the population had adapted over time.
The effects of heat alerts in 20 US Cities between 2001 and 2006 was examined in this paper where the authors recommended an exploration of interventions and communication strategies in addition to heat alerts.
In Gujarat, India in 2010 there was a heatwave with a peak temperature of 46.8 degrees Celsius. The researchers found excess deaths in the population (a 43% increase) but particularly in women during this period.
NHS choices have provided useful information resources here.
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