If you are interested in both your health and new gadgets, you might want to take a look at the Smart UV Checker for smartphones from Amazon.

https://www.amazon.com/Checker-Ultraviolet-Smartphone-Android-iPhone/dp/B01917YSX2/ref=sr_1_1?ie=UTF8&qid=1497411317&sr=8-1&keywords=smart+uv+checker

 

You plug it into the headphone jack and download the software from Google Play (or iTunes.)  Hold the phone in the sunlight and press the button.  It then reports the UV index reading.  The UV Index provided by weather services like Yahoo, by contrast, is a calculated estimate, not a measurement.  Does the difference matter?  Probably not.  Right now Yahoo report a UV index of 3 in BKK while my Smart UV checker shows 2.5.  At midday without clouds Bangkok's UV Index frequently reaches the extreme high of 11.

 

Attention to the UV Index here in Thailand is important, especially for us melanin-deficients, since the tropical sunlight is dangerous, even potentially lethal. 

I just noticed that the same device is available from aliexpress.com.  I should have checked there first.

 

https://www.aliexpress.com/wholesale?catId=0&initiative_id=SB_20170613203442&SearchText=smart+uv+checker