Safe to swim? Play outside? How to keep NYC kids (and adults) healthy during this heat wave.

It's about to get hot in New York City. The region is preparing for its first official heat wave this year — meaning three or more days of Fahrenheit temperatures in the nineties. The heat index, an official measure of how conditions feel to the human body, will be closer 105 degrees.

City-run cooling centers will be open starting on Thursday, and temperatures are expected to peak then and on Friday. This heat wave comes at the end of an already sweltering July. Earlier this month, a stretch of hot days led to a spike in heat-related visits to NYC emergency rooms.

Research released this week found that New York City leads major U.S. cities in the urban heat island effect — a way for judging how the human-made environment increases temperatures and heat health risks for people. A separate report stated that this month’s national heat wave was directly due to climate change.

Dr. Cecilia Sorensen, director of the Global Consortium on Climate and Health Education at Columbia University and an associate professor of emergency medicine, joined WNYC host David Furst on "All Things Considered" to talk about how kids, parents and everyone else can protect themselves during the heat wave.

Their conversation touched on whether outdoor sports such as swimming are still safe to do. They also discussed who is most at risk and whether taking certain medications might increase people’s chances of heat stress or heatstroke.

An interview transcript is available below. It was lightly edited for clarity.

David Furst: We have some very hot weather coming up. How dangerous is a stretch of days like this for the general population?

Sorensen: It really depends on who you are. Everybody has a unique risk profile. For example, people who are elderly, very young children, anybody who works outdoors — people are vulnerable for different reasons. For some people out there in our general population, this is a very dangerous event that's happening.

Well, let's talk about the kids, especially infants and toddlers. They're most at risk because they just aren't capable of taking care of themselves.

How can parents and caregivers keep them safe?

This is such an important point you're making. Infants, toddlers — they can't necessarily express to their caregivers that they're thirsty or that they're overheating.

So caregivers need to be very vigilant in terms of watching them, especially if they're playing outdoors — although I would recommend that parents only bring their kids to play in a shaded area such as a park.

Caregivers and parents should make sure their toddlers and infants are drinking regularly and that they're monitoring for any signs or symptoms of irritability. One sign is if they're not making as many tears as normal. That's a sign of early dehydration.

Caregivers should also avoid over-bundling. You want to kind of dress young children in very loose, lightweight clothing during the heat.

One of the big risks on days like we're about to experience is heatstroke. What exactly is heatstroke?

What should you do if you think that you or somebody else is experiencing that?

Heatstroke happens when your body literally exhausts all the ways that it knows how to cool itself. It can't sweat anymore. You can't breathe any faster. The body just basically succumbs to the heat.

What we see when we diagnose heatstroke is that the core body temperature of an individual gets elevated — usually up above 102 or 103 degrees. This is associated with general confusion; people potentially having seizures; just really not acting right and potentially having difficulty breathing.

If you were to see anybody who looked like that, you would want to contact 911 immediately.

But, of course, we don't want to let it get to that point, right? So look out for early signs of heat illness, such as just feeling very weak and tired, feeling nauseous and feeling dizzy.

These are things that we should be looking out for in ourselves and in the people around us. So we don't let it get so bad.

This year, a lot of New Yorkers are realizing that it's not just the heat and the temperature that they need to monitor on a hot summer day. It's also the air quality.

Why does air quality tend to get worse on hot days, and how dangerous is that?

What we see is that high temperatures actually increase the formation of ground-level ozone.

Ozone — you know, the stuff up in the higher atmosphere — that's the good kind of ozone. But the ozone that occurs down at ground level is usually formed because of products of combustion from tailpipe emissions and so on and so forth.

When you expose that [tailpipe and industrial emissions] to heat, you end up getting ground-level ozone, which can also cause problems usually in similar patient populations that are vulnerable to heat, such as [children], the elderly or anybody who has any underlying, respiratory condition like asthma or obstructive pulmonary disease or any type of cardiac issue.

You talked about kids being outside and trying to stick to the shade, but what about youth sports?

Should kids play sports outside at all in weather like this?

What about swimming? Is that OK?

When there's a heat alert in effect, I would recommend that there not be organized sports. If there are going to be organized sports activities, I think it's so important that there be shade on the site, that there be plenty of hydration and that anybody who is participating in the athletic activity is very closely monitored.

Being in pools is a good idea. Being in the pool can keep you cool. But again, supervising kids who are in pools is very important — making sure they're resting frequently, that they're drinking plenty of water and that you have good supervision.

When we talk about vulnerable populations during a heat emergency, we typically focus on young children and senior citizens.

But should we be doing any sort of rethinking about what constitutes vulnerable populations, given that these heat emergencies are likely going to grow in frequency and intensity as a result of global climate change?

Scientists, including our group, are doing lots of work right now looking at other types of vulnerable populations, including pregnant women. There's been some early data which shows that the risks of stillbirth and a preterm delivery actually go up in the setting of exposure to extreme heat.

We're also thinking about anybody who has any underlying medical conditions — for example, anyone with underlying heart disease or diabetes or high blood pressure.

We're also considering anyone who takes any medications for mental health issues — such as medications for depression or for schizophrenia. Those medications in and of themselves can make your body less able to respond appropriately when exposed to heat.