Lab glossary
Critical wavelength
The wavelength below which 90% of a sunscreen's integrated absorbance between 290 and 400 nm lies. A value of at least 370 nm is commonly required for broad-spectrum or UVA claims.
- Also: λc
The wavelength below which 90% of a sunscreen's integrated absorbance between 290 and 400 nm lies. A value of at least 370 nm is commonly required for broad-spectrum or UVA claims.