Most people think of a heatwave as just a stretch of uncomfortable days that includes sweat, irritability, maybe a bad night's sleep. But ask any emergency physician working through an Indian summer and they will tell you it's far more than that.

Most people think of a heatwave as just a stretch of uncomfortable days that includes sweat, irritability, maybe a bad night's sleep. But ask any emergency physician working…

Experts warn that official heatwave death figures are grossly underestimated.