I den tidligere beskrevne rapport om atomulykken i Japan på kernekraftværket i Fukushima skriver forskerne om sammenhængen mellem temperatur og mortalitet:
Figure 5 displays the temperature-mortality relationship from the estimation of equation (2) to test hypothesis 2.
Following Barreca et al. (2016), our estimates account for lagged physiological effects of temperatures over the past 2 months. 20 Estimates for colder temperatures generally follow patterns from previous studies.
The temperature effect generally decreases in temperatures, with estimates for the two coldest bins significantly different from zero. The point estimates indicate that the effect of an additional hour below 0°C or between 0°C and 4°C significantly increases the mortality rate by 0.028 percent compared to temperatures in the 15- 19°C range. This implies that one day below 0°C increases mortality by 0.672 percent. For comparison purposes, Barreca et al. (2016) find that in US each day below 40°F, which translates to 4°C, increases mortality by 0.34 percent, though their estimate is based on average daily temperatures.21
Estimates for warmer temperatures are small in magnitude and imprecisely estimated. Although this appears to diverge from previous studies, a likely explanation is the high rates of air conditioning penetration, which is close to 90 percent. For example, Barreca et al. (2016) find that temperatures above 90°F, which corresponds with 32°C, affect mortality during periods when AC penetration rates were low, but have much smaller effects as AC rates increased.
During the 1990-2004 period, when AC penetrations rates in the US were comparable to those in Japan, the effect of a day over 90°F is small and statistically insignificant. In light of this, our estimates align quite closely with the previous literature.
We also investigate the underlying cause of death in Table 5 (columns 1, 2). 22 Results indicate that the increase in mortality from cold temperatures is mainly due to cardiovascular disease. Cold temperatures are related to an increase in blood viscosity and vasoconstriction, harming elderly people in particular. A similar effect is found by Deschenes and Moretti (2009) in the US. On the other hand, we do not find any effect of temperature on mortality due to respiratory disease.