Question

a. why is some exposure to the sun necessary? t/i
b. why can overexposure to the sun be a health risk? t/i
c. explain how the uv index has been set up. t/i
d. what is the difference between uva and uvb? t/i
e. what does spf mean? t/i
f. how is sunblock different from sunscreen? t/i
g. list the criteria that you would use to choose the best type of sunscreen for yourself. t/i
h. list other things that you can do to protect yourself from overexposure to the sun. t/i
i. compare exposure to tanning lamps with sun exposure. t/i
j. create an information poster or brochure to educate people about protecting themselves from the sun. t/i a c

Explanation:

A. Sun - exposure is necessary for vitamin D synthesis in the body.
B. Overexposure can cause sunburn, skin aging, and increase skin - cancer risk due to UV radiation.
C. The UV index is set up based on the amount of UV radiation reaching the Earth's surface, factoring in ozone layer thickness and other environmental conditions.
D. UVA has longer wavelengths and can penetrate deeper into the skin, contributing to aging, while UVB has shorter wavelengths and is mainly responsible for sunburn.
E. SPF (Sun Protection Factor) indicates how much longer a person can stay in the sun without getting sunburned compared to not using sunscreen.
F. Sunblock physically blocks and reflects UV rays, while sunscreen absorbs UV rays.
G. Criteria for choosing sunscreen may include SPF level, broad - spectrum protection (against UVA and UVB), skin type, and water - resistance.
H. Other ways to protect from overexposure include wearing protective clothing, seeking shade, and wearing sunglasses.
I. Tanning lamps emit UV radiation similar to the sun, but can be more concentrated and increase the risk of skin damage and cancer.
J. An information poster or brochure could include facts about UV radiation, risks of overexposure, and tips for sun protection.

Answer:

A. Sun - exposure is necessary for vitamin D synthesis.
B. Overexposure can cause sunburn, aging, and cancer risk due to UV radiation.
C. Based on UV radiation levels and environmental factors.
D. UVA penetrates deeper, UVB causes sunburn.
E. Indicates sunburn - prevention time increase.
F. Sunblock reflects, sunscreen absorbs UV rays.
G. SPF level, broad - spectrum, skin type, water - resistance.
H. Wear protective clothing, seek shade, wear sunglasses.
I. Similar UV radiation, but can be more concentrated.
J. Include UV facts, risks, and protection tips.