Schoolyard playgrounds usually have at least one adult who acts as a monitor for the children while playing. City parks may or may not have someone assigned to monitor the playground, so parents should supervise their children whenever possible. If you cannot be there with your child, make sure that there are other adults who can report to you if an accident occurs. Instruct your child to tell an adult if they are hurt on the playground, and give them an information card that contains all contact phone numbers and addresses. If your child is seriously injured, this card will speak for them.
Materials designed to cushion falls.
At the very least, a good playground will have sand or gravel piles placed around the equipment in order to break falls and cushion hard landings. Some parks will use a natural mulch mixture to achieve the same effect, while more modern playgrounds will use rubberized matting materials. Check your child's playground for any of these materials. If there are none, or the material has been scattered to the point of ineffectiveness, you should contact the person responsible for park maintenance and request that more material be brought in. Sand and gravel won't protect a child from the most serious falls possible, but they will absorb enough shock to keep minor injuries from becoming major ones.