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Study of Excessive Temperatures in Enclosed Vehicles

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Study of Excessive Temperatures in Enclosed Vehicles Jan Null
Study of Excessive Temperatures in Enclosed Vehicles
August 2003 (PDF version)
Jan Null, CCM
1,2
Also see: Fact Sheet & 2003 Hyperthermia Fatalities (Children in Vehicles)
BACKGROUND
Every year dozens of children tragically die due to hyperthermia (heat stroke) after being left unattended in cars,
trucks and vans. Over the past five years in the United States 160 deaths of this type have been documented
(Kids and Cars and 4 R Kids Sake
TM
, 2003). Hundreds of other children left in similar situations suffer great
bodily harm and these numbers do not include similar consequences to infirm adults or animals.
OBJECTIVE
This study quantifies vehicle temperatures and temperature changes with time under a variety of meteorological
circumstances.
STUDY DESIGN
Temperature sensors were placed two types of vehicles on sunny days with ambient temperatures ranging from
70 F (21C) to 100 F (38C). The initial interior temperature was regulated to equal the ambient temperature. The
vehicles were in full sun but the sensors in the vehicles were not subject to direct sunlight and were not in direct
contact with any interior surface. Except as noted in the results, the trials were conducted in a mid-sized dark
blue sedan with medium gray interior and all of the windows were fully closed. Using wireless temperature
sensors the ambient outside and the inside vehicle temperatures were sampled every five minutes for at least one
hour. A secondary vehicle (a white mini-van with light gray interior) was used for some tests. Neither vehicle had
tinted windows.
TRIAL SUMMARY
Between May 16, 2002 and Aug 8, 2002 twenty-one trials were conducted on 15 days. Table 1 summarizes the
ambient and inside vehicle temperatures on the primary test vehicle with the windows fully closed. Table 2
compares the temperature in the primary test vehicle on two occasions when the windows were fully closed and
then when they were “cracked” open approximately 1.5 inches (3.8 cm). Table 3 is a summary of two additional
test cases using the primary vehicle and the secondary vehicle.
Table 1. Temperatures F (C), Primary Test Vehicle, Windows Closed
Ambient
10 min 20 min 30 min 60 min
Date
Temp Temp. Temp Rise Temp. Temp Rise Temp. Temp Rise Temp. Temp Rise
6/7/2002
72 (22.2C) 93 (33.9C) 21 (11.7C) 105 (40.6C) 33 (18.3C) 110 (43.3C) 38 (21.1C) 119 (48.3C) 47 (26.1C)
5/16/2002
73 (22.8C) 90 (32.2C) 17 (9.4C) 99 (37.2C) 26 (14.4C) 104 (40.0C) 31 (17.2C) 112 (44.4C) 39 (21.7C)
6/17/2002
74 (23.3C) 95 (35.0C) 21 (11.7C) 104 (40.0C) 30 (16.7C) 110 (43.3C) 36 (20.0C) 125 (51.7C) 51 (28.3C)
6/7/2002
75 (23.9C) 87 (30.6C) 12 (6.7C) 104 (40.0C) 29 (16.1C) 111 (43.9C) 36 (20.0C) 120 (48.9C) 45 (25.0C)
6/6/2002
77 (25.0C) 96 (35.6C) 19 (10.6C) 106 (41.1C) 29 (16.1C) 110 (43.3C) 33 (18.3C) 122 (50.0C) 45 (25.0C)
6/24/2002
78 (25.6C) 95 (35.0C) 17 (9.4C) 105 (40.6C) 27 (15.0C) 107 (41.7C) 29 (16.1C) 117 (47.2C) 39 (21.7C)
6/25/2002
78 (25.6C) 95 (35.0C) 17 (9.7C) 102 (38.9C) 24 (13.3C) 106 (41.1C) 28 (15.6C) 117 (47.2C) 39 (21.7C)
5/30/2002
81 (27.2) 98 (36.7C) 17 (9.4C) 108 (42.2C) 27 (15.0C) 113 (45.0C) 32 (17.8C) 114 (45.6C) 33 (18.3C)
5/24/2002
82 (27.8C) 109 (42.8C) 27 (15.0C) 119 (48.3C) 37 (20.6C) 119 (48.3C) 37 (20.6C) 130 (54.4C) 48 (26.7C)
6/4/2002
82 (27.8C) 107 (41.7C) 25 (13.9C) 116 (46.7C) 34 (18.9C) 121 (49.4C) 39 (21.7C) 132 (55.6C) 50 (27.8C)
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Study of Excessive Temperatures in Enclosed Vehicles Jan Null
6/6/2002
84 (28.9C) 103 (39.4C) 19 (10.6C) 111 (43.9C) 27 (15.0C) 116 (46.7C) 32 (17.8C) 127 (52.8C) 43 (23.9C)
6/30/2002
87 (30.6C) 101 (38.3C) 14 (7.8C) 105 (40.6C) 18 (10.0C) 107 (41.7C) 20 (11.1C) 119 (48.3C) 32 (17.8C)
6/10/2002
88 (31.1C) 105 (40.6C) 17 (9.4C) 117 (47.2C) 29 (16.1C) 125 (51.7C) 37 (20.6C) 137 (58.3C) 49 (27.2C)
7/1/2002
91 (32.8C) 117 (47.2C) 26 (14.4C) 124 (51.1C) 33 (18.3C) 129 (53.9C) 38 (21.1C) 138 (58.9C) 47 (26.1C)
6/5/2002
93 (33.9C) 106 (41.1C) 13 (7.2C) 114 (40.0C) 21 (11.7C) 119 (48.3C) 26 (14.4C) 137 (58.3C) 44 (24.4C)
7/9/2002
96 (35.6C) 113 (45.0C) 17 (9.4C) 128 (53.3C) 32 (17.8C) 132 (55.6C) 36 (20.0C) 140 (60.0C) 44 (24.4C)
Table 2. Temperatures F (C), Primary Test Vehicle, Windows “Cracked”
Ambient 10 min 20 min 30 min 60 min
Comments
Date
Temperature Temp. Temp Rise Temp. Temp Rise Temp. Temp Rise Temp. Temp Rise
7/1/2002
91 (32.8C) 117 (47.2C) 26 (14.4C) 124 (51.1C) 33 (18.3C) 129 (53.9C) 38 (21.1C) 138 (58.9C) 47 (26.1C) Fully closed
7/1/2002
92 (33.3C) 108 (42.2C) 16 (8.9C) 113 (45.0C) 21 (11.7C) 118 (47.8C) 26 (14.4C) 136 (57.8C) 44 (24.4C) "Cracked"
7/9/2002
96 (35.6C) 113 (45.0C) 17 (9.4C) 128 (53.3C) 32 (17.8C) 132 (55.6C) 36 (20.0C) 140 (60.0C) 44 (24.4C) Fully closed
7/9/2002
94 (34.4C) 110 (43.3C) 16 (8.9C) 112 (44.4C) 18 (10.0C) 116 (46.7C) 22 (12.2C) 124 (51.1C) 30 (16.7C) "Cracked"
Table 3. Temperatures F (C), Primary Test Vehicle and Secondary Vehicle
Ambient
10 min 20 min 30 min 60 min
Date
Temp Temp. Temp Rise Temp. Temp Rise Temp. Temp Rise Temp. Temp Rise Comments
5/30/2002
81 (27.2C) 98 (36.7C) 17 (9.4C) 108 (42.2C) 27 (15.0C) 113 (45.0C) 32 (17.8C) 114 (40.0C) 33 (18.3C) Primary
5/30/2002
81 (27.2C) 91 (32.8C) 10 (5.6C) 100 (37.8C) 19 (10.6C) 105 (40.6C) 24 (13.3C) 113 (45.0C) 32 (17.8C) Secondary
6/17/2002
74 (23.3C) 95 (35.0C) 21 (11.7C) 104 (40.0C) 30 (16.7C) 110 (43.3C) 36 (20.0C) 125 (51.7C) 51 (28.3C) Primary
6/17/2002
74 (23.3C) 83 (28.3C) 9 (5.0C) 91 (32.8C) 17 (9.4C) 99 (37.2C) 25 (13.9C) 109 (42.8C) 35 (19.5C) Secondary
METHODS AND PROCEDURES
Vehicle selection. The primary test vehicle was a 2000 Honda Accord. The exterior color is dark blue and the interior is a
medium gray. The windows are not tinted. The secondary vehicle in the study is a 1997 Honda Odyssey minivan which is
white in color with a light gray interior and without tinted windows.
Measurements. Ambient temperatures were recorded with a Davis Instruments Vantage Pro Sensor Suite. Wireless
temperature sensors were placed in the test vehicles which transmitted to and were archived in the Vantage Pro base station.
The temperature sensors had a resolution of 1 F (0.6C) and an accuracy of +/- 1 F (0.6C). All readings were taken out of
direct sunlight.
Experimental procedures. Trials were conducted on a number of cloud-free days with varying ambient temperatures. The
vehicles were parked facing at approximately a 45 degree angle away from the sun to minimize direct sunlight through the
windshield.
Results
In the sixteen cases with the windows fully closed, the average temperature rise was 19 F (10.6C) in the first 10 minutes.
After 20 minutes the average rise was 29 F (16.1C). At the 30 minute mark the average rise was 33 F (18.3C). The average
rise after 60 minutes was 43 F (24C) degrees. In trials that exceeded 60 minutes the interior vehicle readings stabilized. (see
Figures 1 & 2)
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Study of Excessive Temperatures in Enclosed Vehicles Jan Null
Figure 1.
Figure 2.
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Study of Excessive Temperatures in Enclosed Vehicles Jan Null
On the two occasions with the windows “cracked” open the average 10 minute rise was 16 F (8.9C), then 20 F (11.2C) after 20
minutes, 24 F (13.3C) after 30 minutes and the 60 minutes average rise of 37 F (20.1C).
An additional two trials were conducted with simultaneous readings in the primary test vehicle and the secondary vehicle. (see
Figure 3) The average 10 minute rise in the primary test vehicle was 19 F (10.6C) compared to 10 F (5.6C) in the secondary
vehicle. After 20 minutes the respective average rises were 29 F (16.1C) and 18 F (10.0C), and after 30 minutes they were 34
F (18.9C) and 24 F (13.3C). The average one hour rises were 42 F (23.3C) and 34 F (18.9C) respectively.
Figure 3.
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Study of Excessive Temperatures in Enclosed Vehicles Jan Null
ADDITIONAL RESEARCH
This investigation sought to determine the rate and extent of temperature rises in enclosed vehicles using only a single
parameter, temperature, for evaluation. Additional work should be done to examine any influence of relative humidity upon
the change in the vehicle's interior temperature.
Further studies should also be undertaken to delineate the effect of other factors on a vehicle’s interior temperature. These
variables include vehicles of different exterior and interior colors and materials as well as window tinting and window coverings.
In addition to children further studies should look at the effects of heat stress on adults and also pets.
CONCLUSIONS
When temperatures exceed 80 F (26.7C) potentially lethal temperatures of 105 F (40.6C) plus can be reached in less than 20
minutes and when they exceed 88 F (31.1C) lethal readings can be reached in 10 minutes or less. Only minor mitigation
achieved by “cracking” the windows or having a vehicle of larger size or a lighter color.
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Study of Excessive Temperatures in Enclosed Vehicles Jan Null
REFERENCES
Bouchama, Abderrezak, and James P. Knochel. "Heat Stroke." The New England Journal of Medicine 1978: 346.
Constantine, E., and N. G. Gregory. "Hyperthermia in Dogs Left in Cars." The Veterinary Record 5 Oct. 1996: 349-350.
Gibbs, Lynn I. "Heat Exposure in an Enclosed Vehicle." ” Journal of the Louisiana State Medical Society 1995: n. pag.
"Heat-Related Deaths- Four States, July – August 2001, and United States, 1979-1999." MMWR. 28 July 2002
<http://www.cdc.gov/mmwr/preview/mmwrhtml/mm55126a2.htm>.
"Heat-Related Deaths- Los Angeles County, California, 1999-2000, and United States, 1979-1998." MMWR. 5 July 2002
<http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5029a3.htm>.
"Injuries and Deaths Among Children Left Unattended in or Around Motor Vehicles – United States, July 2000-June 2001."
MMWR. 5 July 2002 <http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5126a3.htm>.
Kids and Cars - Statistics. 2003. Kids and Cars. 5 May 2003
King, K., K. Negus, and J. C. Vance. "Heat Stress in Motor Vehicles: A Problem in Infancy." Pediatrics 4 Oct. 1981: 579-582.
Surpure, J. S. "Heat-Related Illness and the Automobile." Annals of Emergency Medicine 5 May 1982: 263-265.
RELATED LINKS
Golden Gate Weather Services
Department of Geosciences, San Francisco State University
Kids and Cars
4 R Kids Sake
Kids in Cars
Davis Instruments Co.
1
Certified Consulting Meteorologist, Golden Gate Weather Services (phone: 510-657-2246)
2
Adjunct Professor, Department of Geosciences, San Francisco State University
http://ggweather.com/heat/ (6 of 6)8/26/2003 1:05:23 AM
... Vehicle heating rates under various outdoor weather conditions are well-studied, with minor cooling effects of 'cracking' a window and small differences by car type or color [3,8,9]. Lethal in-vehicle temperatures are also reached on cloudy days, even though ambient air temperatures can be up to 10 C less when compared to sunny days [10]. ...
... Numerous studies have demonstrated the ability to easily collect environmental information within an enclosed vehicle to determine heating rates [1,[8][9][10]], yet few studies [26][27][28][29] have attempted to extend findings to physiological implications of said exposures to children. The current study furthers these efforts to demonstrate an ability to estimate the T c progression and the time to reach potentially dangerous T c value under differing solar exposure conditions, vehicle type, and day from similar starting cabin microclimate conditions. ...
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Pediatric deaths due to children being left in hot cars remain a significant yet preventable public health concern. The current study aims to demonstrate the influence of vehicle type, time of day, and solar exposure (sun or shade) on the energy balance and core temperature (Tc) of a hypothetical two-year old boy left in a vehicle on a hot day. Cabin temperatures and relative humidity were collected within six enclosed vehicles under sun or full shade in Tempe, Arizona. These variables and radiation estimates were used to estimate the human energy balance and final Tc across 76 measurement cycles lasting approximately 60minutes. Interior temperatures averaged 39.5°C and 47.6°C in the shade and sun, respectively, at steady-state. Based on the specific heat of a human body, the average Tc after 60 minutes in shaded or sun-exposed vehicles was estimated to reach 38.2±0.29°C and 39.1±0.41°C, respectively, with a significantly higher final Tc in sun-exposed vehicles across all days and in the shaded minivan. Extrapolation to 2 hours is estimated to result in heat injury in the sun. Results demonstrate the influence of radiation on a child's thermal balance in a hot and dry environment. In real-world situations, it is critical to acknowledge variability between children, the starting car environment, and climate (e.g., humid versus dry), and that a child left in any vehicle car can experience potentially lethal core temperatures if forgotten, as shown by vehicular heat stroke statistics. Findings may improve public messaging and reinforce the need for policy action and technological adoption to prevent injury and death.
... Temperatures inside vehicles left in the sun during summer months have been extensively surveyed [1][2][3][4][5] and are well known to reach extremely large values, often in excess of 65 C. When driving a car just after such extreme conditions, the driver is at least initially exposed to a severe thermal environment characterized by very high air and radiant temperatures. Although the thermal environment severity in the vehicle drops due to declining air temperature associated to the inflowing outdoor air, radiant temperatures remain significantly larger than air temperatures for some time, since interior surfaces do not cool as quickly. ...
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Purpose: This paper investigates the thermal conditions inside a passenger car driven after it was left a few hours in a shade-less parking lot, and the related implications for the driving performance. Materials and methods: Experimental results for twelve tests carried out in four different vehicles are presented and discussed. Each test is characterized by means of the predicted core temperature tcore of the driver after 60 minutes, as calculated by a heat stress model. The fractional performance loss is calculated by adjusting existing algorithms for office tasks to accommodate literature data on driving-related tasks, and then re-casting the algorithm as a function of tcore instead of the air temperature ta. Results: Based on measured temperatures and humidities, fractional performance losses up to 50% are predicted even for relatively simple tasks such as keeping the vehicle on a straight course. Performance losses in excess of 75% are predicted, under the most extreme thermal conditions, for demanding tasks, such as correctly identifying a signal and reacting in due time. Conclusions: The implementation in technical standards on heat stress assessment of two new thresholds is recommended. The lower threshold, to be set at tcore ≅ 37.1 °C, is aimed at ensuring that the subject is able to carry out demanding mental tasks without appreciable performance loss, while the higher threshold, to be set at tcore ≅ 37.2 °C applies to simpler tasks.
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Heat stroke is a life-threatening condition clinically diagnosed as a severe elevation in body temperature with central nervous system dysfunction that often includes combativeness, delirium, seizures, and coma. Classic heat stroke primarily occurs in immunocompromised individuals during annual heat waves. Exertional heat stroke is observed in young fit individuals performing strenuous physical activity in hot or temperature environments. Long-term consequences of heat stroke are thought to be due to a systemic inflammatory response syndrome. This article provides a comprehensive review of recent advances in the identification of risk factors that predispose to heat stroke, the role of endotoxin and cytokines in mediation of multi-organ damage, the incidence of hypothermia and fever during heat stroke recovery, clinical biomarkers of organ damage severity, and protective cooling strategies. Risk factors include environmental factors, medications, drug use, compromised health status, and genetic conditions. The role of endotoxin and cytokines is discussed in the framework of research conducted over 30 years ago that requires reassessment to more clearly identify the role of these factors in the systemic inflammatory response syndrome. We challenge the notion that hypothalamic damage is responsible for thermoregulatory disturbances during heat stroke recovery and highlight recent advances in our understanding of the regulated nature of these responses. The need for more sensitive clinical biomarkers of organ damage is examined. Conventional and emerging cooling methods are discussed with reference to protection against peripheral organ damage and selective brain cooling. © 2015 American Physiological Society. Compr Physiol 5: 611-647, 2015.
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To evaluate the heat burden in parked cars, a study was done to measure inside car temperatures in different situations. A large car and a small car were parked in direct sunlight and in shade. In direct sun, the highest temperatures recorded in the small and large cars were 78 C and 65 C, respectively. The highest temperature in shade for the small car was only 44 C. There was a tremendous buildup of heat inside the car parked in direct sun as opposed to shade (p less than 0.001), and the small car heated more quickly than the large car under similar conditions (P less tan 0.001). Leaving the windows partially or fully open is not protective. With partial ventilation the highest recorded temperature in the small car was 70 C. These findings suggest that the heat burden of poorly ventilated, parked cars exposed to direct sun can be enormous. The common practice of leaving infants, toddlers, elderly people, and pets in cars under these conditions could cause them tremendous heat stress. The potential hazards of this practice should be recognized and special precautions should be taken.
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Children have died from heat stress because they have been left in closed automobiles. Changes in the internal temperature of various sized automobiles left in the Brisbane summer sun were examined. With all windows and doors closed, this temperature rose from an ambient level of 36 C to a maximum of 67 C within 15 minutes and remained there until the doors were opened. Slightly lower temperatures were found for light colored sedans and station wagons. However, all readings were significantly above ambient and all produced an environment unacceptable for a child. Temperatures approaching ambient were only achieved with ventilation provided by windows at least 200 mm (half) open. A lesser gap (50 mm) resulted in interior temperatures exceeding 50 C, which is still too hot for children. Infants left in such an environment will lose fluid quickly from sweat and could become as much as 8% dehydrated in four hours. Subsequently the cerebral manifestations of heat stroke would ensue. Parents and pediatricians should be warned of the danger of heat stress if children are left in a closed automobile.
Heat Exposure in an Enclosed Vehicle
  • Lynn I Gibbs
Gibbs, Lynn I. "Heat Exposure in an Enclosed Vehicle." " Journal of the Louisiana State Medical Society 1995: n. pag.
Heat Exposure in an Enclosed Vehicle Journal of the Louisiana State Medical Society 1995: n. pagHeat-Related Deaths-Four States, and United States, 1979-1999
  • Lynn I Gibbs
Gibbs, Lynn I. "Heat Exposure in an Enclosed Vehicle." " Journal of the Louisiana State Medical Society 1995: n. pag. "Heat-Related Deaths-Four States, July – August 2001, and United States, 1979-1999." MMWR. 28 July 2002 <http://www.cdc.gov/mmwr/preview/mmwrhtml/mm55126a2.htm>.
Journal of the Louisiana State Medical Society 1995: n. pag
  • Lynn I Gibbs
Gibbs, Lynn I. "Heat Exposure in an Enclosed Vehicle." " Journal of the Louisiana State Medical Society 1995: n. pag. "Heat-Related Deaths-Four States, July -August 2001, and United States, 1979-1999." MMWR. 28 July 2002 <http://www.cdc.gov/mmwr/preview/mmwrhtml/mm55126a2.htm>.