Laptops and burns – the problem

60.3 Celsius, it was very hot. If you’ve been using laptops for a while, you might have heard about the dangers of laptops burning your thighs.  If you have, you’ve probably also heard about the Swedish guy who suffered burns to his penis.  When I reviewed my employers’ recent draft “computer use” policy, I noticed the laptop section was missing a section on laptop heat.

So I had a look at the available medical research.  And there isn’t much.  There is one 2004 study which found that skin burns will occur over a period of 8 hours at 42.5 Celsius (108.5 Fahrenheit).  There was the 2008 case of a 24 year old male suffering a 8×3 cm burn on his right thigh.  He had fallen asleep while watching a movie.  Six hours later, he woke up with a deep second degree burn.  And there is the case of the Swedish chap with the burnt penis.

I decided to run a test, to see what heat a laptop generates.  And I thought it would be interesting to look at the differences between the various Windows versions.

The test rig:
 
Dell E4200 Laptop, towel, PassMark BurnInTest software

Highest temperature seen: 60.3 Celsius / 140.54 Fahrenheit

Temperature under the towel
This was measure by placing the temperature sensor under the first layer of a towel.  The laptop was then run until it reached an operating temperature.

  Celsius Fahrenheit
DOS 37.9 100.2
Windows XP SP3 38.6 101.5
Windows Vista SP2 39.4 102.9
Windows 7 37 98.6

Fan exhaust port temperature
This was measured by placed the temparture sensor outside the fan exhaust port.

  Celsius Fahrenheit
Windows XP SP3 42.3 108.1
Windows Vista SP2 45.2 113.4
Windows 7 43.2 109.8

 

Differences in operating systems?
No as much as I thought.  I was expecting Vista and Windows 7 to be cooler than MS-DOS and Windows XP, as they have later technology (power/thermal management) built right in. 

About that 60.3 Celsius measurement you mentioned earlier?
I had the laptop resting on a blanket, which was resting my lap.  My lap felt warm, so I grabbed the thermometer.  60.3 Celsius! 

Further reading
2002: The Lancet – Lap burn due to laptop computer
2004: Journal of Burn Care & Rehabilitation – Temperature threshold for burn injury: an oximeter safety study.
2008: Journal of Burn Care and Research – Thigh Burn Associated With Laptop Computer Use

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