2. Case Narrative
A 10-year-old sister finds her 2-12-year-old brother dead inside an empty
toy chest. Apparently, the chest’s hinged wood lid was too heavy for him to
open. His death was ruled as physical asphyxiation from oxygen
insufficiency; however, the county medical examiner, during forensic
evaluations, was uncertain if this boy’s death was unintentional or
homicidal. She requests services of an industrial hygienist to determine
oxygen depletion profile over time inside the toy chest. The chest was
tightly sealed, so there was no air exchange while the boy was inside
The interior dimensions were 35" × 18" × 15"
The boy weighed 34 pounds naked
3. Assumptions:
Ambient concentration of oxygen was 20.95% (v/v).
Boy’s body density was 1.07 g/mL.
Oxygen consumption by boy was 0.13 L O2/minute.
Exposure was at, or near, sea level, say <1000 feet.
Nobody opened the lid while the boy was inside.
He had good health with no CO poisoning risk factors.
4. Analysis
PART- 01 :
Volume of Toy Chest Coffin = 35”x18”x15” = 9450 Cubic inches = 5.47 Cubic feet = 154.87 L
Weight of the boy = 34lbs ( given)
Weight of the boy = 15,422 gram
Boys Volume = 15422 / 1.07 = 14413 mL = 14.413 L
Net volume of toy chest with boy inside = 154.87 L – 14.413 L = 140.46 L
Volume of O2 when boy entered toy chest = 140.46 x 0.2095 = 29.43 L
5. Analysis
PART- 02 :
After 30 minutes: 30 minutes × 0.13 L/minute = 3.9 L O2 consumed
After 60 minutes: 60 minutes × 0.13 L/minute = 7.8 L O2 consumed
After 120 minutes: 120 minutes × 0.13 L/minute = 15.6 L O2 consumed
After 120 minutes: (existing O2 concentration/initial O2 concentration) × 100
= (15.6 L/29.43 L) X 100
= 53.0% O2 remains after 2 hours
20.95% O2 in ambient air × 0.53 = 11.1% O2 in toy chest after 2 hours
At near 12% O2, unconsciousness is approaching, and death occurs at nearly 6% O2 or less
6. Conclusion
As we see, this boy’s asphyxiation death was slow—perhaps over 3 hours
Of course, he’s exhaling CO2 which stimulates the heart’s carotid body CO2 receptor to
increase both respiration rate and heart rate
With diminishing oxygen, he gets weaker, strength goes down, and his ability to continue
screaming for help will decrease.
His most likely profound fatigue from escaping attempts accelerate his oxygen consumption
and CO2 generation into the surrounding “air.”
7. Recommendations to Toy Manufacturers
An opening, say 1" × 12" at the top front under the lid’s edge with equal area openings at the
back side near the bottom will promote natural ventilation
Body warmth produces a “chimney effect,” air rises and exits at top front, with make-up air
naturally entering through the back bottom area
Cries for help could be more easily heard with the openings.
Manufacturers must install hazard warnings with pictographs
A lighter lid would have allowed this boy to extricate himself or at least to open lid partially
to scream for help.
A police whistle attached by a short chain to the inside, with parental training, could
augment good safety engineering design.
