UV & You

UV & You

Home
Notes
Chat
Archive
About
What's the REAL SPF of that sunscreen?
.... why it can differ from lab tests and for different sun elevation angles.
 • 
Richard McKenzie
When bad news is good news
Like a good joke, it's all in the timing ...
 • 
Richard McKenzie
Rule-of-thumb for UV blocking by clouds
They equivalent SPF is less than 5.
 • 
Richard McKenzie
2
UV blocking by clothing
Just keep your shirt (and trousers) on
 • 
Richard McKenzie
9
Sunscreen heresy
Why are the SPFs of sunscreens so high these days? Is it a good thing?
 • 
Richard McKenzie
7
Sunscreen use
How high, how much and how often?
 • 
Richard McKenzie
2
Scaling UV damage to human skin
... is 10 x 1 always the same as 1 x 10?
 • 
Richard McKenzie
9
UV & You
UV & You
Please join up to receive free occasional postings on the intersection of UV radiation, climate, and health, by atmospheric physicist Dr. Richard McKenzie (Lauder, New Zealand).
Recommendations
HEATED
HEATED
Emily Atkin
The Crucial Years
The Crucial Years
Bill McKibben
Disjointed
Disjointed
Hamish McKenzie
On Substack
On Substack
Substack Team
© 2025 Richard McKenzie
Privacy ∙ Terms ∙ Collection notice
Start writingGet the app
Substack is the home for great culture