Last year 18-year-old Aaron McKinzie of Kansas City was operated on for what his doctors thought was chronic asthma.During surgery a small white plastic building block was removed from one lung. Neither Aaron nor his parents could remember when he has aspirated the block.

Each year thousands of children are maimed and even killed by products that break or are used improperly. During the Christmas season, when toy manufacturers move into high-gear to lure kids, wear down parents and manipulate grandparents, injuries are at a yearly high. The Consumer Product Safety Commission has launched a two-year campaign to make the public aware of the potential hazards of toys and playground equipment.

"We are trying to get community groups and leaders interested," says Bill Menza of the Division of Consumer Information. Strict government regulation of toys is difficult, he explains, as one toy may be regulated under several different government agencies.

A doll, for example, may be regulated by the Consumer Product Safety Commission, but the fake baby food that it eats is under the jurisdiction of the Food and Drug Administration. Government regulation, stresses Menza, is no substitute for parent awareness and discretion.

Although bicycles and rollers skates lead statistics in injuries requiring emergency-room treatment, Menza warns that hazards may come from unexpected sources. "One of the most dangerous pieces of equipment is a toy chest. The lid falls down on the back of the child's neck causing injury or even asphyxiation."

The hazard, however, may not be intrinsic in the toy itself, but may be the result of improper or inappropriate use. A 5-year-old, not mature enough to do a 1,000-piece jigsaw puzzle depicting the emerging nations of the Third World, might prefer feeding the pieces to his year-old brother.On many toys, the ages for which the toy is intended is clearly marked.

As the child grows out of the nursery and into the playground, parents are confronted by new potential dangers. Some 167,000 playground accidents resulting from falls from equipment or faulty equipment are reported annually. "But again," says Menza, "the fault is often not in the equipment, but in poor supervision." Studies have shown that some parents never supervise their children on the playground.

For parents planning to buy playground equipment, the Consumer Product Safety Commission suggests that swing sets be installed at least six feet from walls, sandboxes and walks. Backyard equipment should never be erected over hard surfaces, but over sand or grass and the equipment should be firmly anchored in the ground. Next to supervision, maintenance is the key to equipment safety: Tighten or replace loose bolts and nuts, replace or repaint rusted parts and oil moving parts.

Most important, parents and indulgent grandparents should screen the toys and equipment that Santa puts under the Christmas tree. Is Jimmy old enough for a trampoline? Is 4-year-old Susie going to use the hair dye meant for her doll on her own hair (or, worse, try to swallow it)? What (or who) is Johnny going to shoot with his superpowered laser gun?

Parents should follow the same guidelines in shopping for children's toys and equipment as they do when shopping for their clothes, says Menza. "Products should be appropriate for a child's age, interest and ability."

For further infromation, contact the U.S. Consumer Product Safty Commission, Washington, D.C. 20207.