WHEN I think of “laughing gas,” I always picture in my mind the popular weapon of The Joker that causes its victims to laugh to their death. What a way to die in the DC comics universe.

However, while laughing gas is made entertaining in the fictional world of comic books, it is not amusing at all in reality. Or is it? In 2016, the Global Drug Survey reported it as the seventh most popular recreational drug worldwide, or specifically in the 50 survey-participating countries. In fact, its use as a recreational drug is longer than its medical use.

It is so because laughing gas is chemically nitrous oxide. It is calming, pain-relieving, odorless and colorless.

Nitrous oxide contributes 6.24 percent of the total global radiative greenhouse gases, reported Yujin Zhang and colleagues at the Chinese Academy of Science (Lanzhou, Gansu) in 2018 (Biosciences Discussions). At such level, it can decrease the ozone layer by five percent. It ranked third in its contribution, second only to carbon dioxide and methane. Its presence depletes the stratospheric ozone.

At the nutritional level, nitrous oxide reacts with vitamin B12, resulting in the selective inhibition of a key enzyme in the metabolism of methionine and folate. German anesthesiologist Jorg Weimann noted in Best Practice & Research Clinical Anesthesiology that, when this happened, errors in the synthesis of the genes (deoxyribonucleic acid), purine, and thymidylate occurred. A long-term exposure to the laughing gas at high concentrations had been known to cause megalobastic bone-marrow disease and other neurological disease symptoms.

In tooth extraction for children, nitrous oxide is the second most commonly used pain reliever and sedation substance (46 percent), next only to general anesthesia (52 percent), observed Shion Chi of the Dankook University Sejong Dental Hospital in 2018 (Journal of Dental Anesthesia and Pain Medicine).

Either way, the use of nitrous oxide can irreversibly inactivate vitamin B12, which is an essential vitamin to humans. To some patients, especially those with vitamin B12 deficiency, it can be fatal.

It can also cause hypoxia (oxygen deprivation). Thus, its misuse can be as fatal. In the United Kingdom, 17 deaths due to laughing gas inhalation were recorded between 2006 and 2012, which could be an underestimate.

However, nitrous oxide is not without good reputation in the medical industry. It had been found used as anesthetic for labor pains in the early decade of the 21st century. It is also commonly used among dentists during tooth extraction. Medical use of nitrous oxide was estimated to contribute below 0.05 percent of the total global greenhouse emission every year.

The next time you are in surgery, dental or otherwise, ask the surgeon: are you using nitrous oxide for my operation?