What's in the 'explosive balloon' that poisons students?

According to the school, the students bought 11 packs of "explosive balloons" and brought them into the classroom to play. They used their hands to hit the balloons hard, causing the toy packages to swell and explode. The surrounding children who inhaled the gas released from the balloons showed signs of breathing poisoning.

Technically, a "pop-up balloon" package contains two substances: sodium bicarbonate (NaHCO ₃ ) and a liquid contained in a sealed plastic bag, an acid called citric acid (C ₆ H ₈ O ₇ ). Sodium bicarbonate, when in contact with an acid such as citric acid, will cause a very violent reaction that produces a large amount of carbon dioxide (CO ₂ ), new salt, and water.

When playing, children will use their hands or feet to hit or stomp hard on the "explosive balloon" toy package. The plastic bag containing citric acid will burst, react with sodium bicarbonate to create a large amount of _CO2 gas. The volume of the gas toy package suddenly increases about 4 times its original volume and the bag bursts, creating a loud explosion.

There are two reasons why children get poisoned when playing with "explosive balls", sometimes life-threatening.

First is carbon dioxide poisoning, also known as carbon monoxide. Carbon monoxide has four effects on the body: headaches due to increased carbon monoxide in the blood causing constriction of blood vessels in the brain, constriction of blood vessels in the brain reduces blood flow to the brain, leading to lack of oxygen and causing headaches; vomiting; difficulty breathing.

As _CO2 concentrations increase further, coughing, sneezing, runny nose and difficulty breathing can be life-threatening...

Second is dermatitis, eye inflammation caused by citric acid and sodium bicarbonate. The remaining chemicals above will be directly sprayed on the body, causing irritation to the skin and mucous membranes of the eyes.

Skin symptoms include itching, burning, redness. On the eyes, it can lead to eye damage such as tearing, keratitis, conjunctivitis.