Q What are the health risks of inhaling diesel exhaust fumes? I rode along in a school bus for a field trip and was alarmed that I could smell exhaust fumes in the bus.

A You should be alarmed. Diesel exhaust is a noxious soup of gases and particles that can have serious health effects when inhaled, said Chuck Stroebel, a research scientist at the Minnesota Department of Health. Children, in particular, are at risk from diesel exhaust fumes.

Of biggest concern are the ultrafine particles called microparticles that can go deep within the lungs or even enter the bloodstream, Stroebel said. They can trigger asthma and other respiratory responses as well as cancer and other diseases over time. In addition, toxic gases such as carbon monoxide are found in diesel exhaust, as are other known carcinogens.

Minnesota and several other states have passed laws that limit school bus idling in order to reduce exhaust near schools. However, Stroebel said, the law in Minnesota is not effectively enforced.

Smelling exhaust fumes inside a bus means the vehicle is self-polluting. Vehicle self- pollution is a known and not uncommon problem. But there's no law that requires exhaust levels to be measured inside a school bus, although at least one state, Vermont, is considering it.

Voice your concerns to school and district officials. The Legislature last year made funds available for Clean Air Minnesota to retrofit school buses and minimize the problem. That means public or private schools, even those using contract bus services, can get their fleets converted free of charge.

To take advantage of this program, contact Emily Franklin at Minnesota Environmental Initiative's Clean Air Minnesota 612-334-3388, ext. 114.

Do raisins contain iron?

Q Are raisins a good source of iron? I always thought they were, but recently I was told they are not.

A At one time they were. Raisins used to be processed using iron equipment that leached iron into the raisins.

New methods however, use stainless steel equipment. Raisins themselves aren't significant iron sources. One cup of raisins would have about 2.6 milligrams of iron, according to nutritionist Julie Miller Jones of St. Paul.

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.