Shade Trees Don't Always Protect Enough.

As long as you can see the Sky even when under the Shade, you are exposing Yourself to UV rays.

In the heat of summer we seek relief from the hot sun by sitting under shade trees, beach umbrellas, grandstands, etc. But while this shade might keep you cool, it isn't protecting you from the ultraviolet (UV) radiation rays--those harsh, damaging rays from the sun.

Sitting in the shade often doesn't provide adequate protection say scientists at Queensland Institute of Medical Research in Brisbane, Australia, because dust particles can scatter UV light into shady nooks.

"In effect, as long as you can see the sky even when under the shade, you are exposing yourself to UV rays that are scattered or reflected by molecules in all parts of the sky," says Dr. Peter Parsons, of the Queensland Institute of Medical Research. "This means that an average fair-skinned person could suffer sunburn in the shade after less than one hour, while not even realizing the dangers."

The Queensland team at rated UV protection of house awnings, a sun hat, and trees. To protect against sunburn and UV-B-induced cancers, shade should have a protection rating (in their study) of at least 15. Hats rated 10 across the nose and eyes, but ranked 2 for the rest of the face. House awnings facing away from the sun rated 6.4. A tree's shade protection ranged primarily from 2 to 6, though rarely up to 10. A fair-skinned person could have a sunburn in less than an hour at midday under most trees.

Despite the limited protection shade provides, Dr. Parsons said that it has rightly been promoted as an additional defense against solar damage, and providing increased shade by planting trees, building shelters, and wearing hats is recommended.

The study did not directly address some other sources of shade. And the scientists pointed out that it is likely that beach umbrellas (which provide shade but leave the sides exposed) and stadium grandstands with obversely angled roofs (where the height of the roof allows exposure to appreciable sky radiation) are even higher risk areas for unwitting exposure to UV than under trees.

The scientists say that more detailed research on shade remains to be done. But the study highlighted the need for physical and behavioral aspects to be taken into account when providing or promoting shade as a shield from solar UV. Some recommendations they offered are:

1. The limitations of shade protection should be included in public health skin cancer education programs.

2. Structures and tree planting should be designed to provide attractive outdoor areas enclosed in such a manner as to exclude as much sky radiation as possible.

3. More research is needed to build up comprehensive information in relation to shade.

It should also be noted that a number of factors affect dosages of UV radiation, including latitude, season, time of day, and sunscreen usage.

Tom R. Kovach is a writer living in Park Rapids, Minnesota.