This is not something that happens often, but it happened. A Car battery which was broken or damaged caused the death of mother and 3-year-old daughter. They were found with no signs of life in their car. The cause of death was determined to be poisoning with very toxic gas: hydrogen sulfide from a car batter battery, which has been placed under the driver’s seat. In this case, the smell was so intense that first responders were forced to initially retreat. Car batteries are usually sealed and should not emit any gas. However, this case showed that there is always the exception.
A car battery consists basically of two lead plates which are immersed into sulfuric acid. During regular charging and discharging cycles of batteries containing sulfuric acid, there shouldn’t be any hydrogen sulfide production. So how can hydrogen sulfide occur? It can be produced by the broken battery or by heat production when overcharging it. In such conditions, hydrogen can be released from the sulphuric acid solution which can form the poisonous hydrogen sulfide gas.
Hydrogen sulfide is a colorless gas with the characteristic smell of rotten eggs. It is very poisonous, corrosive, and flammable. It’s heavier than air, so it’s accumulating at the bottom of poorly vented spaces. Once you can smell it, it means that its concentrations are high enough to be toxic. It affects many systems in the human body and the one which is the most affected is the nervous system.
When air has been contaminated with hydrogen sulfide even a few breaths can cause a loss of the sense of smell and the lack of awareness of surroundings. In the case of even short exposure to high concentration of hydrogen sulfide, death can occur in few moments. The main cause of death is because of inhibitory properties of hydrogen sulfide, which stops cells’ ability to absorb oxygen. In short, the victims die from suffocation. The best course of action if you think you are smelling hydrogen sulfide gas is to vent the space, and leave until it’s properly vented.