Sun exposure not only depends on how long one stays in the sun but also on environmental factors that significantly alter the effects of irradiation. Understanding these factors is crucial for effective sun protection.
In summer, it is necessary to protect oneself more from the sun due to the angle at which the sun's rays reach the Earth. However, even in spring caution is required: when the desire to be outdoors and the sun's rays intensify day by day, the risk of sunburn can be underestimated.
>In any season, the hours of greatest intensity are the middle of the day (from 11:00 AM to 3:00 PM), when the sun is highest on the horizon. The effect is at the peak in summer, when it is advisable to always seek shelter in the shade. However, even in midwinter excessive exposure can be risky if one is at low latitudes, near the tropics or the equator, or at high altitudes, where the effect of altitude can be compounded by the reflection of snow..
LATITUDE
Moving towards the poles, the sun's rays strike the earth more obliquely, making irradiation in the extreme North and South areas of the world less intense, even in summer. Conversely, the inclination of the sun's rays tends to be lower closer to the equator, where the sun is overhead all year round. In these areas, it is necessary to take every precaution in any season, seeking shade during the central hours of the day and protecting oneself even when the sky seems overcast.
ALTITUDE
As one climbs a mountain, the atmosphere becomes more rarefied and the filter against solar irradiation reduces. This is why, with the onset of spring and especially in summer, there is a risk of severe sunburn. Even in midwinter, it is important to protect the skin when at high altitudes. The effects of ultraviolet rays on the skin remains even if one does not burn and can manifest over time with premature skin aging or with an increased risk of skin cancers.
ATMOSPHERIC CONDITIONS
Part of the ultraviolet rays also pass through clouds, especially when they are not continuous or solid. Therefore, a cloudy sky is not enough to avoid sun-related risks if exposure is still high for the season, hour, altitude, and latitude. On the other hand, the clearer the sky, the greater the exposure to UV rays. Moreover, when windy, the risk increases because the temperature can drop, misleading people about the actual intensity of the irradiation.
REFLECTION
An additional factor that can amplify the effects of solar irradiation is the reflection produced by surfaces such as snow, sand, water.
UV INDEX
To help people make informed and cautious choices about their exposure to the sunlight, health authorities have been providing a UV index for several years, indicating the level of risk expected for each day and city in relation to the season and atmospheric conditions.