Playground sand (silica) is different from normal sand, because they're intended to be rounded particulates instead of tiny angular shards that are more abrasive. However, there are problems specific with silica that introduce significant concerns to be considered.
Playground sand or silica is used extensively, yet typically inadequently maintained in most playgrounds.
Cost: Between $20 to $30 per square foot over 25 years, if installed outdoors and maintained and/or replaced as recommended by the National Resource Center (NRC); Initially around $3 per square foot for a 12" depth; Ongoing about $3 per square foot every two years if replaced, or $1 per square foot to replenish every year or so to maintain the 12" depth
Safety: Typically the second best and most common playground safety surfacing with pretty good HIC scores for lower fall heights, not really safe for maximum fall heights of over ten feet
Maintenance: Keeping birds and animals from leaving anything behind is nearly impossible, with many playgrounds raking the sand daily to attempt to ineffectively remove any pathogenic fecal material, and maintenance can be cumbersome whether it's annual replenishment or replacement as recommended every two years by the NRC*
Hazards: Pathogens and microbes are unfortunately very common to playground sand, given how animals like to use it for something we wish they wouldn't on playgrounds, and organic materials can propogate and multiply quickly if there's moisture present (in one playground, an infrared camera captured a mountain lion visiting every two to three days to let the local domestic pets know it's really their territory!)
Liabilities: Just the potential for spreading pathogens and microbes to children playing within playground sand can lead to all sorts of nasty results, ranging from Hepatitus-B, blindness, or other serious conditions (a 19-year-old young man surfing a couple of days after a rain had to get a heart transplant due to fecal pathogens attacking it, even at that few parts per million in the ocean water from urban run-off it caused too much damage to properly heal on its own, and remember that COVID-19 also is from a zoonotic source!); in addition, most insurance policies will not cover any claims related to the use of silica due to the potential for exposure to silicosis
Playground sand, or more appropriately silica, is perhaps the most widely used playground safety surfacing, due mostly to its low cost. Silica is defining the rounded and non-abrasive particulates that differ from normal sand, and this is the only type of sand to be used within playgrounds. It's recommended that playground sand only be used on indoor playgrounds. Wait... what?!? Yeah, how many playgrounds with sand do you see indoors? It's really because they become a giant catbox, attracting birds and animals that do what they do after they've eaten and processed their food... in the sand. In one park playground, something too large to be from a pet kept being discovered, so placement of an infrared camera captured a local mountain lion doing its business at least two to three times a week. Even though pet waste carries pathogens, for feral animals and birds, it's often worse.
If you can't place your playground with sand indoors, then you're supposed to guard against access by birds or animals outdoors by covering it when not under adult supervision. Okay. How, exactly? That's the point being made here. You really can't prevent birds and animals from doing what they do when they're outdoors, unless you've built a finely meshed netted atrium around the entire playground. Once again, highly unlikely. So, the pathogens build up, the microbes and parasites multiply & propogate, especially if the sand gets any moisture. This is why the NRC (*National Resource Center for Health and Safety in Child Care) has recommended for decades that playground sand (or EWF) be removed and replaced every two years. The problem is, it's expensive to remove and replace twelve inches of sand, and these recommendations are rarely, if ever, followed.
That issue is just one, because years ago most insurance companies chose to disallow any claims related to the use of silica, and any claims for silicosis or the use of silica. This means your insurance company can actually decline or cancel coverage for your playground with sand, then you're left holding the bag if something goes wrong. Truthfully, contracting silicosis from playground sand contact is highly improbable. Insurance companies were most concerned about how much silica was being used in synthetic turf fields, and drew their conclusions to what happens when silica is used for sandblasting. Not even close to the same thing. Sandblasting pulverizes and shatters those little rounded particles into a fine airborn dust that can be inhaled if proper breathing filtration isn't used. That, as well as glass production, is typically how silicosis is contracted, the lung damage is irreversable, and normally fatal.
For overall fall safety, playground sand (silica) provides decent impact protection for falls from ten feet or less, if it's maintained properly at the twelve inch depth and not compacted into a solid mass anywhere. The dispersion method of impact attentuation is what it provides, yet many playgrounds with sand neglect the necessary upkeep necessary to maintain it properly. We've created a single page info sheet in pdf for your to access that covers the Important Health Issues on Playground Sand.
So the bottom line with using playground sand is, don't touch it with bare skin, because pathogens can pass through skin on contact, even quicker on the thinner skin of young children. Keep it up to the proper depth, do your best to keep out the birds and animals, rake it regularly, and replace it when it gets too full of organic material that can spread pathogenic microbes or parasites.