Shelf life of sunscreen

According to Traveland Leisure, a recent study in Brazil showed that the ability to protect the sun's UV rays from the sun was reduced over time. However, how often a change is still an unanswered question.

The study focused on Brazil's glass classification system based on the lens's darkness and UV resistance. Each eyeglass must pass the test round, in which they are placed under a fake sun bulb 450 watts continuously for 50 hours, at a distance of 30cm.

Sunscreen is an indispensable item to protect the eyes against the harmful effects of UV rays.(Photo: Gulf Luxury).

These figures are equivalent to using 2-day glasses under the average summer sunshine or 4 days in winter. However, because Brazil is near the equator, the solar radiation intensity here is stronger than usual. Therefore, in fact, this test is only equivalent to 23.5 hours in the sunshine in the city of Sao Paulo.

The study's authors said that the glass strength tests should also consider the fact that Brazilians wear an average pair of glasses for about 2 hours a day for 2 years.

"It is still too early to confirm that UV protection is impaired over time if the life expectancy test is done with a fake sun and the current parameters are not reviewed." - Liliane Ventura, professor at the University of Sao Paulo, author of the study, said.

Before the official conclusion, the scientists still recommended that the glass should be replaced after 2 years of use . To be sure, users can check UV protection at radius stores.

Do not buy glasses where the glass is exposed directly to the sun.

In addition, users can protect themselves by buying glasses from reputable brands, with glasses labeled " 100% UV protection" or "UV400" . The price, polarity or darkness of the glasses is not a factor to consider. However, the size and medium of the glass is very important.

"A big pair of glasses will be great when you are working outdoors for long periods of time. For example, when you ski or go to the sea and suffer from UV reflection from all directions, big glasses will protect you better " - Dr. Jeff Pettey, spokesman for the American Academy of Ophthalmic AAO, said.

In addition, doctors also recommend that glasses should not be purchased where the glass is exposed directly to the sun, such as at an outdoor store or on the beach.