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Kids, Cars, and Heatstroke: A Lethal Summer Mix

By: Bob Henson 3:21 PM GMT on July 02, 2015

Any child’s death is heartbreaking, but there is something uniquely poignant about the way in which dozens of U.S. youngsters die each year: trapped in an oven-like vehicle on a quiet summer day. “That pain is every day. It’s always there,” one grief-stricken mother told CNN seven years after she inadvertently left her 9-month-old baby in her car. Close to 400 children have died across the nation over the last decade in this tragic way.

You don’t have to live in Phoenix or Houston for your car to become a death trap in summer heat. Jan Null (Department of Meteorology & Climate Science,San Jose State University) discovered how easy it is for a vehicle to heat up when it’s getting the intense solar radiation of summertime. Formerly a lead forecaster for the National Weather Service in the San Francisco Bay area, Null was interviewed by media in 2001 after a baby’s death in San Jose on an 86°F day. “Out of scientific curiosity, I started casually tracking temperatures in my own vehicles and was startled at not only how hot the readings were but also how rapidly they rose,” he recalled. He soon joined forces with two Stanford University Hospital doctors, Catherine McLaren and James Quinn, to carry out a more thorough analysis that was published in Pediatrics in 2005. The take-home finding was that full sunlight hitting a dark sedan boosted interior temperatures by more than 6°F every 10 minutes, even when outdoor temperatures were in the 70s. The paper concluded: “Even at relatively cool ambient temperatures, the temperature rise in vehicles is significant on clear, sunny days and puts infants at risk for hyperthermia. Vehicles heat up rapidly, with the majority of the temperature rise occurring within the first 15 to 30 minutes. Leaving the windows opened slightly does not significantly slow the heating process or decrease the maximum temperature attained.”

Figure 1. Even when temperatures outside are only 80°F, sunshine entering a closed vehicle can push the temperature to 109°F in just twenty minutes. After an hour, the car’s interior air can reach a blistering 123°F. Cracking windows does not reduce the ability of the air to reach such high temperatures. The sunshine entering the car rapidly heats up surfaces (the dashboard or steering wheel can reach 180 – 200°F on an 80°F day). These surfaces, in turn, heat up the interior through convection and conduction as well as by longwave radiation, in much the same way that an asphalt parking lot sends heat upward. An hour’s worth of warming is depicted in this QuickTime animation. Image credit: GM and Jan Null.

Null is passionate about providing good scientific information to advocates, policymakers, and emergency responders about how hot cars can get and the circumstances that lead to children dying in vehicles from heatstroke. His website noheatstroke.org includes a set of frequently updated statistics that bring home the problem vividly. Of the 637 such deaths recorded from 1998 to 2014, just over half involved children who were “forgotten,” many of them left in a vehicle by a parent or caregiver rushing to work in the morning. Maps that show the location of each incident from year to year make it abundantly clear that latitude is no protection: 2014 saw deaths in Michigan New York, and Connecticut, and 2015 has already seen a confirmed death in northern Idaho. Perhaps surprisingly, Null reports that only 20 states have laws regarding leaving children unattended in vehicles.

Figure 3. Geographic distribution of heatstroke deaths involving children and vehicles, 1998 – 2014. Image credit: Jan Null.

Here are Null’s safety recommendations:

Never leave a child unattended in a vehicle—not even for a minute!
—If you see a child unattended in a hot vehicle, call 911.
—Be sure that all occupants leave the vehicle when unloading. Don't overlook sleeping babies.
—Always lock your car and ensure children do not have access to keys or remote entry devices. Teach children that vehicles are never to be used as a play area.
—If a child is missing, always check the pool first, and then the car, including the trunk.
—Keep a stuffed animal in the carseat, and when the child is put in the seat, place the animal in the front with the driver. Or place your purse, briefcase, or cell phone in the back seat as a reminder that you have your child in the car.
—Make "look before you leave" a routine whenever you get out of the car.
—Have a plan that your childcare provider will call you if your child does not show up for school.

For a look at how heat affects the human body, check out our latest WU infographic (excerpted at the bottom of this post).

And don’t forget about Fido!

Smokey the Wonder Dog (right) joins Bob in reminding you that a vehicle roasting in the summer sun can be dangerous to pets, too. Hundreds are believed to die around the country each year after being left in hot cars. At least 16 states have laws of various types that prohibit endangering a pet’s life by leaving it unattended in a parked car. As of July 1, police officers across the state of Washington can break into parked cars as needed to rescue pets, with limits on their liability for vehicle damage. The pet’s guardian can face a $125 fine.

The Humane Society offers these tips on how you can help if you see a pet in a parked car on a sunny summer day:

—Take down the car's make, model and license-plate number.

—If there are businesses nearby, notify their managers or security guards and ask them to make an announcement to find the car's owner.

—If the owner can't be found, call the non-emergency number of the local police or animal control and wait by the car for them to arrive.

The American Veterinary Medicine Association suggests: “Before you put your pet in the vehicle, ask yourself if you really need to take your pet with you--and if the answer is no, leave your pet safely at home.”

Have a happy and safe Fourth of July weekend, everybody!

Bob Henson

Figure 3 (below). An excerpt from “Heat and the Human Body,” the latest infographic from Weather Underground. The full version, created by WU’s Jerimiah Brown, can be found online.

European heat wave continues
Brutally hot conditions continued over Europe on Thursday, with the hottest temperatures shifted eastwards over Eastern France, the Netherlands, and Western Germany. The temperature in Maastrict, the Netherlands, hit 100.8°F (38.2°C), just missing the Netherlands' all-time hottest temperature record of 101.5°F (38.6°C), set on August 23, 1944 at Warnsveld.

According to Meteo France, on Wednesday, the high temperature at the official Montsouris station in Paris, France hit 103.5°F (39.7°C), the second warmest temperature ever measured there, and not far from Paris' all-time record of 104.7°F (40.4°C) set in July 1947. At least three stations in France set all-time heat records on Wednesday:

Boulogne-sur-Mer (station opened in 1947): 35.4°C (Previous record 34.8°C on 08/11/2003)
Dieppe (station opened in 1949): 38.3°C (Previous record 37°C on 07/09/2006)
Melun (station opened in 1947): 39.4°C (Previous record 38.9°C on 08/12/2003)

Three tropical cyclones in the Pacific
A Typhoon Watch is up for Guam for Typhoon Chan-hom, which is expected to pass very close to the island late morning U.S. EDT time on Saturday as an intensifying Category 2 storm. The NWS in Guam is putting out special advisories and local statements on the typhoon.

Chan-hom will be the second typhoon to affect the island this year; in May, the eye of Category 2 Typhoon Dolphin passed through the channel between the islands of Guam and Rota, bringing sustained winds of 84 mph, gusting to 106 mph, to Andersen Air Force Base on Guam. Dolphin knocked out power and damaged some homes, but the islands escaped serious destruction.

The Philippines are watching Tropical Depression Ten, which is expected to skirt the northern island of Luzon over the weekend as a Category 1 typhoon. In the South Pacific, a rare winter tropical cyclone, Raquel, is drenching the Solomon Islands.

Jeff Masters


The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.