Hot car calculator sums up the risk of leaving children and pets behind
Developer Dominik Czernia tells us how the online tool can be used to save lives
New York dad Juan Rodriguez was on his way to work one July morning, en route to his twin children’s school. Except he forgot to take the detour – and failed to notice them asleep in the back seat. By the time the veterans’ hospital counsellor returned to the car that evening, his children had suffered heatstroke and died. It is a tragedy oft repeated across the world, including in the UAE – in cars and school buses alike.
Psychologists list low human memory functions (memory lapses or false memories) as potential reasons why harried parents and caretakers may suppress the fact their children have not been dropped off and / or are still in the car. Some believe it is perfectly safe to leave young ones (and helpless pets) in a vehicle for only a few minutes, as they dash about their day.
Dominik Czernia, a PhD student at the Institute of Nuclear Physics in Krakow, Poland, wants to ingrain in to people why doing so, even for a little while, is dangerous and potentially deadly.
Every summer in the Middle East brings with it incredulous online posts of how, seemingly impossibly, the thermostat is blinking at, say, 58°C in your vehicle – even though the temperature is meant to be 40°C outside. Czernia says this “fact” is at the crux of his Hot Car Calculator, a tool he developed for the Omni Calculator Project.
He says he began to pay closer attention to the topic after a fatal accident in his home country of Poland, when a father forgot his child in a car. Czernia began researching the effects of being left in a vehicle under varying circumstances, such as the cloud cover at the time, the colour of the car (dark or light), whether the windows are open or closed and the external temperature.
He and his friend Lukasz Bialek, a doctor, came up with the idea of the Hot Car Calculator. Bialek wrote the segment on the health consequences of heat illness for Czernia’s report. The calculator, freely available online, allows users to estimate the temperature in a car and the expected body temperature of a child over time, with the intention of showing that once you have this knowledge, it will forever be part of your conscious and subconscious mind.
“For example, at 21°C, even on a cloudy day in a light car, it only takes 45 minutes for a child’s body temperature to reach 38°C, causing hyperthermia, sweating and thirst. In a dark car, keep in mind, things move even faster,” says Czernia.
Bialek further notes of the consequences of a heightened human body temperature: after 20 minutes you experience hyperthermia, sweating, thirst and major discomfort. After 35 minutes, there is severe sweating, a flushed reaction and increased heart rate, while children with epilepsy may start convulsing.
For example, at 21°C, even on a cloudy day in a light car, it only takes 45 minutes for a child’s body temperature to reach 38°C, causing hyperthermia, sweating and thirst. In a dark car, keep in mind, things move even faster.
The 60-minute mark is life-threatening, with a risk of fainting, dehydration, vomiting and breathlessness. And 100 minutes after being stuck in a closed car, a child’s body can heat up to 41°C, and children can experience severe headaches, dizziness, confusion, hallucinations and delirium; this is a certified medical emergency state.
The reason a vehicle’s interior gets hotter than its surroundings is down to the greenhouse effect, Czernia explains. “It’s the same effect that is the main cause of global warming. Car windows act similarly to the Earth’s atmosphere; they are almost transparent to light radiation, but prevent thermal radiation from leaving. Therefore, solar radiation goes through the windows, heating the dashboard, seats and floor of the car. Those elements then emit thermal radiation, but this is blocked by the windows and windscreens when it tries to escape. This traps the heat radiation in the vehicle, causing the cabin temperature to increase dramatically.”
Cracking the windows open is better because air flows freely through the car, but it is still not safe, says Czernia. “Spending 40 minutes inside a car with partly opened windows can increase the interior from, say, 30°C to 35°C – it’s the same adverse health risk. Parents must also think of security – cars with open windows can be targeted by thieves.”
Open windows can allow rain in, too, as well as bees and other insects.
How to use the Hot Car Calculator
1. Free to use online, the calculator requires you to first type in the outside air temperature. “Our calculator uses a model that is most accurate on warm days when the air temperature ranges from about 20°C to 50°C,” says Czernia.
2. Next, select one of two ways in which you wish to estimate the maximum car interior temperature: based on either solar radiation or on the sky cloud coverage. If you choose cloud cover, decide how much of the sky is covered with clouds (clear sky, few clouds, scattered, broken or overcast), with clear sky being 0 per cent and an overcast sky being 100 per cent. If you choose solar radiation, select the day and one of the capital cities across the world. “We calculate solar radiation theoretically. For more precise estimations, you can type in the latitude of your town or city, which is easily found on the internet,” says Czernia.
3. Enter whether your car colour is light or dark, and if your car has either closed or partly open windows. Once you have input this data, the calculator throws up two interactive graphs. A blue curve shows the change in the car’s internal air temperature, while a yellow- red curve represents the estimated body temperature of a two-year-old.
On the day of writing this piece, for example, the outside temperature in “mostly sunny” Abu Dhabi is 38°C. The skies are clear, but we input the cloud cover as few clouds (so 20 per cent). In a light car with the windows partly open, this works out to an interior temperature of 50.2°C and a child’s body temperature of 39.9°C – both 65 minutes later. If the windows are closed, a two-year-old’s body would be at 40.2°C in the same period. The maximum temperature that your car’s interior could reach is 78.7°C.
“Remember that even 20 minutes are enough to cause a lot of harm,” says Czernia. “It’s why I’ve used eye-catching and interactive graphics … [for people] to use at least once and then forever be cautious.”
Updated: September 10, 2019 09:33 AM