What is SPF? What do the parameters on sunscreen mean?

What is SPF?

SPF (Sun Protection Factor) is an index showing the ability of sunscreen to protect the skin against UVB rays (the type of rays that cause sunburn and skin cancer) in a certain period of time.

The minimum SPF in sunscreen is 15 and the highest is 100 . According to international standards, 1 SPF has the ability to protect the skin and limit the harmful effects of UV rays for about 10 minutes . That means a sunscreen with an SPF of 15 will work for 150 minutes, and SPF 50 is 500 minutes.

However, the above is only an approximate number, so the actual effectiveness of sunscreen still has differences due to many different factors such as environment, product quality, …

What SPF number is best?

The higher the SPF number, the longer the sun protection time and the more effective the UVB protection.

– SPF 15 blocks 93% of UVB rays

– SPF 30 blocks 97% of UVB rays

– SPF 50 blocks 98% of UVB rays

Meaning of sunscreen index

What are UVA and UVB rays?

UVB rays (Ultraviolet B): Ultraviolet rays of wavelength B

– Short wavelength, impact on the epidermis.

– Causes sunburn, skin redness, skin burns, reduces skin immunity, dehydration and skin irritation.

UVA (Ultraviolet A): Ultraviolet rays of wavelength A

UVA is a type of light with wavelengths from 400 to 315 nm. The active time of UVA rays is as follows:

+ From before 10 am – after 2 pm accounts for about 99% of the ultraviolet rays reaching the ground.

+ From about 10 am to 2 pm accounts for 95%.

– Can destroy connective tissue, destroy firmness and elasticity, which is the cause of skin darkening and skin aging (melasma, wrinkles, sagging…). Easy to accumulate and cause some dangerous cancers.

– It is worth noting that UVB rays can be blocked by fog, clouds, glass or windows, but UVA rays cannot. So whether it’s a shady day or indoors, we are still exposed to UVA rays. If you are subjective in prevention, you can completely be attacked by ultraviolet rays.

PA (Protection Grade of UVA)

This is an indicator that indicates the level of protection against UVA rays of the product.

The Japanese cosmetics industry divides PA into levels:

PA+: Has UVA protection

– PA++: Relatively good UVA protection

– PA+++: Good UVA protection

– PA++++: Very good UVA protection.

In the US markets, people don’t use the PA index, so that’s why sunscreens in Vietnamese markets don’t have that number instead, it will say Broad-spectrum or UVA to represent. for the product’s ability to block UVA rays.

Infographic summarizing sunscreen index

What is SPF? Together with the information of the index on the sunscreen will determine the quality of the product. So here you will understand how to choose the right sunscreen for you.

How much sunscreen should I use?

Most people think that the higher the SPF, the better the protection against UV rays. But this is not entirely true, because:

• The use of sunscreen with a high SPF is not necessarily suitable for the user’s skin.

• Sunscreens with a high SPF often focus on protecting against UVB rays rather than UVA rays.

• The sun protection time of a sunscreen with an SPF of over 60 is not much better than that of SPF 50, but when using a high SPF type, it stays on the skin longer, easily causing clogged pores and damaging the skin. damage, thereby rapidly appearing signs of skin aging.

Small attention when choosing to buy and use sunscreen

• The higher the SPF is not necessarily good, only choosing a sunscreen with SPF 30 is enough to protect your skin.
• Choose sunscreen with reputable brands, avoid creams of unknown origin.
• Whether it’s cool or just sitting in the office, you should wear sunscreen

You can refer to Sunplay Skin Aqua sunscreen products, Biore sunscreen, … which have been studied for the appropriate level of sun protection, helping to protect the skin effectively.

Source: Vinmec Hospital, Thanh Nien Newspaper

Choosing the best sunscreen for your skin depends on the SPF index. Not every SPF is higher, the better, because it can affect the skin and the sun protection effect is no more than lower SPF types.

You will be interested in:

>>> Difference between physical sunscreen and chemical sunscreen

>>> How to use effective sunscreen for non-burnt skin

Good experience lassho.edu.vn