Marisa hates cleaning day. She sneezes and sneezes and sneezes again. Her nose itches and her eyes get red. She feels as if she's going to keep on sneezing for the rest of her life.

Is Marisa allergic to cleaning up her room? Well, in a way. She is allergic to dust mites, tiny creatures that live in carpets, pillows, curtains, bed linens, mattresses, upholstered furniture -- and stuffed animals.

"Dust mites love the places we love," says Bonnie L. Renfro, a children's allergist in Kissimmee, Fla. "In a way, they clean up after us because they eat the skin scales we shed."

Dust mites are invisible unless you happen to have a powerful microscope. Seven thousand of them could fit on your thumbnail, Dr. Renfro says.

Even a clean house contains dust mites. Your mattress alone may have 200,000 of them. As the mites consume skin scales, they give off a waste product that gets deep into fibers in carpeting and blankets. These waste products can cause a sneezy, itchy allergic reaction. Each dust mite gives off about 20 waste particles every day, so if you have 200,000 mites in a mattress, you have a lot of the allergen, too. An allergen is a substance that brings on an allergic reaction. The trouble is, dust mites and their waste are invisible.

Another common allergen found in houses and gardens is mold. Mold grows in damp places like basements, air-conditioning units, piles of leaves that have been rained on, compost heaps and bathrooms. Molds also grow on house plants. Molds can be killed with a mixture of household bleach in water. Outside, avoid damp places with piles of fallen leaves if mold makes you sneeze. You may have to skip walking in the woods.

When Marisa heard about dust mites, she was upset. She worried that she'd have to throw her stuffed animals away. Plus she likes to sleep with one on her pillow, even though she's in fourth grade. (Don't think Marisa is babyish. Lots of kids have a favorite animal with them during the night. Even many college kids take a beloved stuffed toy along when they go away to school.)

Dr. Renfro's four children all have allergies. But she hasn't banished stuffed animals from her house. Instead, she and her children have an agreement. "We select the 'toy of the week,' " she says. "The toy each child chooses gets washed in hot water and put through the dryer. At the end of the week, that animal goes back to the laundry, or another is chosen and the first one put away."

Hot water kills dust mites that have taken up residence in your stuffed animal. Before you wash the animal, however, make sure it can withstand hot water. Washable toys usually have labels that tell you how to keep them clean. Some older toys may not be washable. Those may have to be used just for display. Your washed animals may begin to fade. But like the Velveteen Rabbit in the story, that just shows that they've been loved.

One helpful suggestion is to store stuffed animals in a hammock hung from a corner of your room. That way, you can still see them even when they're "banished" from your bed. Another thing allergic kids can do with toys is store them in a glass-fronted bookcase where they can be seen but won't collect as much dust.

Some allergists are stricter about letting allergic kids keep stuffed toys. But Dr. Renfro's philosophy is to learn to live in harmony with allergies. However, she says, "with children who have more severe allergies, you may need more vigorous control."

To live in harmony with her allergies, Marisa made the following changes in her routine:

She chooses one animal a week, washes it in hot water and puts it on her pillow.

She and her mom replaced her bedroom carpet with washable cotton scatter rugs that can be laundered every week. They also got rid of her dust ruffle and replaced her mini-blinds with a plain but colorful pull-down windowshade .

They covered Marisa's mattress with a special dust-proof cover.

Marisa's "chore list" now omits dusting and sweeping. Instead, she helps out with dishwashing, cooking and kitchen cleanup. Now when cleaning day comes, Marisa heads for the kitchen instead of the broom closet.Tips for Parents

Environmental controls are crucial to allergy management, says Bonnie L. Renfro, MD, a pediatric allergist. Even if you hang on to your dust producers, there are many measures you can take to reduce allergens at home, from taking down curtains to buying a new high-tech vacuum cleaner. For other suggestions, the "Allergy Almanac," a free publication of the Foundation for Allergy Care and Treatment (FACT), can be ordered ($1 postage and handling): FACT, P.O. Box 13367, Silver Spring, Md. 20911-1336.

Catherine O'Neill is a children's writer.

Use this four-week chart to decide which stuffed toy will be "Toy of the Week" in your house. In each space below. write a description of each toy. (If you don't have stuffed toys anymore, use the chart to make a schedule for a younger brother or sister, neighbor or friend.)