[MargaretR]

Originally Posted by Neil

Not being awkward but all you know is that they are reading the same temperature. You can't say that means they are 'calibrated' correctly

They match an old fashioned thermometer I have had for years.

Acclimatisation is more difficult for the elderly
Acclimatization


"Circulatory system
With the elderly, there is a decreased ability to pump and redistribute blood to the skin. There is a decline in cardiac reserve and age-related reduction in vascularity which subsequently decreases peripheral blood flow. These changes would reduce the efficiency with which heat can be removed.15 Furthermore, conditions such as atherosclerosis, heart failure, and hypertension reduce even further the body’s ability to respond to extreme heat.16 Sweat glands
Sweat gland function gradually declines in the age range of the 70s and 80s.17 Aging causes a reduction in the number of sweat glands and the sweat gland response.16 Lifetime ultraviolet exposure and other environmental factors contribute with chronological age to reduce sweat gland responsiveness.18
Cardiovascular disease—how does it affect heat response?
Aging is associated with reduced cardiac output as well as less redistribution of blood flow from the intestinal and renal circulations.19 In a study comparing the cardiovascular responses of young and old men during direct passive heating to the limits of thermal tolerance, Minson et al. found that reduced cardiac output was primarily the result of a lower stroke volume, since the older men were able to increase their heart rate to a similar extent as the young men.20 However, the older men had to attain a greater proportion of their heart rate reserve. People suffering from cardiac disease are unable to augment their cardiac output adequately to produce the necessary level of vasodilation to dissipate heat by evaporation, conduction, and convection.20
Behavioural age-related and chronic disease-related changes
Described risk factors for death or morbidity during severe heat episodes characterize the “at risk” population as being socially isolated and elderly (esp. over 75 years old),21 living in urban areas, often housebound or unable to care for themselves independently, and disproportionately living in institutions.22-25 From experimental studies on people in their 40s and 50s, it appears that healthy older people may be able to attain levels of physiologic acclimatization close to younger counterparts, but lack of activity and lack of exposure to a range of temperatures may deprive them of the opportunity to effect this protective adaptation.14 However, people with cardiac and renal impairment may not be able to achieve these results."