Q Does one get any vitamin D benefits from the sun through window glass? How about through car windows?

A No. The type of sunlight that stimulates the body to produce vitamin D does not penetrate glass.

Although it's possible to meet vitamin D needs through exposure to sunlight, it can be difficult if not impossible:

• In northern climates, such as Minnesota, the sun is too low in the sky from October to April to stimulate vitamin D production.

• Complete cloud cover reduces UV energy by 50 percent; shade (including that produced by severe pollution) reduces it by 60 percent.

• Sunscreens appear to block vitamin D-producing UV rays, although in practice people generally do not apply sufficient amounts, cover all sun-exposed skin, or reapply sunscreen regularly.

• Those with dark skin need more light exposure to get their vitamin D.

• Fish, liver and egg yolk are the foods that naturally contain vitamin D; a few products such as milk contain vitamin D.

If you have limited sun exposure, live in a northern climate, have dark skin or eat few vitamin D-containing foods, you probably need to take a supplement. Ask your doctor how much.

Includes information from the National Institutes of Health

State Fair taxes

Q How does the State Fair Board monitor the concessionaires so the sales, state and federal taxes are fairly paid, as well as the fees to the State Fair?

A As independent business owners, concessionaires are required by law to report and pay state and federal taxes directly to the government. The Minnesota State Fair does not "monitor" their payment of taxes, but other agencies of government do, and noncompliance with tax laws can be grounds for cancellation of a concession license.

Concessionaires operating on a percentage fee formula are required to report their gross receipts from sales on a daily basis, for the preceding business day, during specified hours at the fair's concession office.

Based on this reporting, concessionaires pay the State Fair the percentage amount specified in their license agreement. Noncompliance with this procedure constitutes cause for automatic revocation of privileges granted to the licensee and immediate license cancellation.

Information provided by Minnesota State Fair

Send your questions to Fixit in care of the Star Tribune, 425 Portland Av. S., Minneapolis, MN 55488, or call 612-673-7032, or e-mail fixit@startribune.com. Past columns are available at www.startribune.com/fixit. Sorry, Fixit cannot supply individual replies.