"UVB sunlight is associated with the hottest part of the day, between 10am and 3pm, when the sunlight is brightest," said Dr Pourzand who works in the University of Bath's Department of Pharmacy & Pharmacology.
"UVB affects the outer layer of the skin and is the primary agent responsible for skin blistering and peeling after sunburn.
"UVA sunlight is typically associated with the cooler parts of hot summer days, before 10am and after 3pm.
"UVA was once thought to have a minor effect on skin damage, but now it is considered to be a major contributor as it penetrates deeper into the skin than UVB.
"It is overexposure to UVA that causes the redness and inflammation, or erythema, associated with sunburn.
"The UVA component of sunlight is dangerous as it acts as an oxidising agent that forms free radicals which trigger chain reactions that potentially lead to DNA damage that can convert healthy skin cells into cancerous ones."