Sun, UV and heat illness

Two different risks, one open field

A playground in the sun exposes children to ultraviolet radiation and to heat. They are related but they are not the same problem, and they need different answers.

UV causes sunburn and long-term skin damage. It does not track with how hot the day feels, it peaks around solar noon, and it is strongest in late spring and summer, at high altitude and near reflective surfaces. Heat causes heat illness, which is a whole body problem, and it also heats equipment surfaces to the point where they burn on contact. The contact burn side of that is covered in detail in heat and burn risk, so this page stays on UV exposure and on heat illness in the child rather than in the slide.

This page is general information about recognizing warning signs and reducing exposure. It is not medical advice, and it does not replace guidance from a clinician who knows the child.

When UV is worst, and what the UV Index tells you

The UV Index is a forecast scale published for US locations and defined by the EPA². It runs from 0 upward with no fixed ceiling, and the bands map to how fast unprotected skin is affected.

Three things surprise people. UV passes through thin cloud, so an overcast day can still deliver a high index. UV rises with altitude, roughly a few percent per thousand feet, so mountain playgrounds burn faster than coastal ones at the same latitude. And UV reflects: light concrete, pale sand, water play features and snow all bounce UV back up under hat brims and under shade sails. A child standing in the shade of a sail over a white concrete pad still receives reflected UV from below.

Shade as the primary control

The CPSC handbook treats shade as a design consideration rather than a requirement, and no US standard mandates a shade structure on a public playground¹. That means shade is a budget decision, and it is one that gets cut first and regretted later.

Where to put it, in priority order:

1. Over the slide and the metal or dark plastic components. Shade is the only reliable way to keep chute temperatures down.
2. Over toddler equipment. The youngest children have the thinnest skin, the least ability to say they are too hot, and the least tolerance for heat load.
3. Over caregiver seating. Adults who are comfortable stay outside and stay watching. See caregiver comfort and seating.
4. Over the sand or water play area, where children stay in one place for long stretches.

Shade options and their costs are compared in shade structures, and the site level thinking about orientation, sail angles and where the sun actually lands at 2pm sits in shade and heat design. If you are planting for shade, planting and landscape covers species choice, root conflict with surfacing, and the fruit and thorn problems that make some otherwise good shade trees a poor fit next to a play area.

Surface temperature is not air temperature

A 90 F day is not a 90 F playground. Dark plastic, bare metal, black poured rubber and synthetic turf routinely run tens of degrees above air temperature in direct sun, and they heat within minutes of the sun reaching them. That matters here for two reasons beyond contact burns: hot surfacing radiates heat upward into the child standing on it, and a play area surrounded by hot surfaces stays hot after the air has started to cool in the evening.

Surfacing choice changes the number. Light colored engineered wood fiber and sand stay closest to air temperature. Artificial turf and dark unitary rubber sit at the hot end. The temperature detail, including which materials peak highest and how long they take to cool, is in the heat and burn risk guide.

Heat illness in children: what to watch for

Children heat up faster than adults. They have more skin area relative to body mass, they produce more heat per pound during activity, and younger children do not reliably notice thirst or ask to stop. A child deep in play will keep playing past the point where an adult would sit down.

Water, and where it comes from

Hydration is unglamorous and it is the intervention that gets forgotten at the design stage. A drinking fountain inside or adjacent to the play area changes behavior, because children drink when water is 20 feet away and do not when it is a walk across a park.

Practical points for a site manager:

• Specify a fountain with a bottle filler and a low bowl children can reach. Adult height only fountains exclude the users who most need them.
• Check that the fountain is on the accessible route, not stranded behind a curb. Accessible routes and surfacing covers the route rules.
• In winterized climates, fountains get shut off seasonally. Know the date, and tell staff to bring water for the shoulder weeks.
• For programs, a labeled water bottle per child plus a refill point beats a shared cooler for both hydration and hygiene.

Scheduling outdoor play in a hot climate

In Phoenix, Houston or Fresno, the answer is not more shade alone, it is a different timetable. Programs that run successfully through a southern summer tend to do the same handful of things:

• Move the long outdoor session to the morning, before 10am where the schedule allows, and keep the afternoon session short.
• Set written trigger points. A common structure is a heat index threshold for shortened play, a higher one for shade only play, and a highest one for indoor activity. The National Weather Service heat index charts are a reasonable basis⁴.
• Touch test hot components before each session and close anything too hot to hold for five seconds.
• Run water play as the hot weather alternative if the site has it.

Childcare playgrounds covers how licensing rules interact with required outdoor time, and how recess scheduling and supervision load interact in a school setting. Longer term climate patterns and what they mean for materials and shade budgets are in heat and climate.

Sunscreen, realistically

Sunscreen works, and federal sun safety guidance treats it as one layer alongside shade, clothing and timing³. It is also the control most likely to fail in practice, because it needs to be applied 15 to 30 minutes before exposure, reapplied every couple of hours and after water play, and applied to the places everyone misses: ears, the back of the neck, the tops of feet in sandals, and the part in the hair.

In institutional settings there is a second layer of difficulty. Many US states have passed laws allowing students to carry and self-apply sunscreen at school without a prescription, but rules on staff applying it to young children vary by state and by licensing agency, and some programs require written parent permission. Decide the policy before summer, write it down, and tell families what the program will and will not do. For children under six months, the usual advice is shade and clothing rather than sunscreen, and a pediatrician is the right source for an individual child.

What to decide next

If you are building or renovating, price shade in the first budget pass rather than as an alternate, because it is the item that disappears when bids come in high. Budget breakdown shows where it usually sits. If you are running an existing site through a hot summer, write the schedule triggers and the touch test into the daily and weekly checks so it survives staff turnover. If you are choosing surfacing now, weigh the temperature question alongside cost and impact performance, because the cheapest surface in the bid is often the hottest one in August.