SPF
A white T-shirt only provides an average UPF of 7 - if you can see through a piece of clothing when you hold it up to the light, UV radiation can penetrate it and reach your skin.
The fact that all of these hats have a UPF of 50 was a huge plus!
The New York-based foundation said fabric with a UPF rating of 30 to 49 offered very good protection.
A fabric that is rated UPF 50 allows one 50th of the sun's rays to penetrate the clothing and reach the skin.

SMART Vocabulary: related words and phrases

Miscellaneous units of measurement
acre
acreage
caloric
dioptre
farad
fathom
firkin
flashpoint
hectare
joule
MHz
newton
radian
refractive index
röntgen
Scoville scale
SI unit
sievert
sun protection factor
watt

You can also find related words, phrases, and synonyms in the topics:

Protection and protectors
Physics: radiation & radioactivity

UPFnoun[C or U] (FOOD)

abbreviation for ultra-processed food or foods: food prepared using industrial processes, usually involving a large number of ingredients, many of which would not normally be used in preparing or cooking food at home:
UPFs are foods and drinks that have gone through several industrial procedures.
The UPF category also includes most bread, breakfast cereal and cereal bars.
Ultra-processed foods (UPFs) are industrially produced foods containing ingredients not available in home kitchens, and are the main source of refined carbohydrate and added fats in the modern diet.
Here are some tips on how to avoid ultra-processed foods (UPF) in the diets of infants and young children.
Is ultra-processed food (UPF) causing obesity in children and could it be addictive?

SMART Vocabulary: related words and phrases

Various qualities of food
candy coat
candy-coated
citric
cordon bleu
creamily
farmhouse
fruity
halal
herby
homegrown
homemade
hoppy
nutritious
nutty
sharpness
shelf-stable
single-estate
store-bought
sugar-coated
unbalanced

You can also find related words, phrases, and synonyms in the topics:

Natural and artificial