Here's how often you should reapply sunscreen, according to an expert

Fun in the sun could lead to sunburn, or worse, DNA damage, one dermatologist says. To avoid any skin irritation this summer, here’s when you should apply sunscreen and how much to use.

As the summer season kicks off, many may find themselves increasingly exposed to the sun. Dr. Renee Beach, a dermatologist, told CTV's Your Morning on Monday that without skin protection, this exposure can cause DNA damage, which could develop into skin cancer.

Beach says although many may only wear sunscreen in the summer, protecting the skin should be a "year-round thing."

"Even when we can't see the sun…we still have UVA (Ultraviolet A)," she said. "So that's the rays that come through windows (and) windshields, it's the ones that we see coming off sometimes the reflection off of snow, for example."

When there is exposure to direct sunlight, Beach says people come into contact with UVA and Ultraviolet B (UVB) rays. To protect the skin, sunscreen is needed.

"SPF stands for sun protection factor, and what you'll commonly hear is that SPF 30 is what should be on our skin," Beach said. "The reason why is because that equates to about 97 per cent of ultraviolet radiation or UV protection from our daytime sunlight."

Applying the correct sunscreen and the right amount are other important factors in protecting the skin.

Beach recommends people use about a quarter teaspoon of sunscreen on the face. If applying sunscreen to both the face and neck, they should use about half a teaspoon.