In charcoal-heated hookahs, the fact that the smoke passes “through water” creates a sense of safety for many users; however, data show this is a dangerous misconception. Under incomplete combustion, charcoal produces large amounts of carbon monoxide (CO) and other toxic byproducts of combustion. CO is a colorless, odorless gas that binds to hemoglobin ~200 times more strongly than oxygen, impairing tissue oxygenation.
How and How Much CO Does Charcoal Produce?
Laboratory studies demonstrate that the charcoal used in hookahs is the main source of CO, and that “quick-light” coals release much higher amounts of CO compared to natural coals. This difference has been clearly measured in experimental setups simulating a typical 90-minute hookah session.
Meta-analyses and measurement studies consistently find that CO exposure from hookah smoke is significantly higher than that from cigarettes; some summaries point to exposure levels up to 9 times greater than a single cigarette.
Acute Effects: From Headache to Poisoning
Emergency medicine literature regularly reports CO poisoning cases linked to hookah use; especially with quick-light coals, CO production can reach “extremely high” levels. This results in headaches, dizziness, nausea, and in severe cases, syncope and hospitalization.
Cardiovascular System: Endothelial Function and CO’s “Mask”
Clinical studies show that hookah smoking acutely impairs arterial endothelial function; however, the high CO generated by charcoal combustion is a strong vasodilator, which can partially mask this impairment. In other words, while vascular function worsens, CO’s temporary widening effect can make the condition appear better than it is.
Respiratory and Oxidative Stress
Recent reviews emphasize that there is no scientific basis for believing that water acts as a filter; exposure to PAHs (polycyclic aromatic hydrocarbons), heavy metals, and other toxins remains significant. Oxidative stress and inflammation are also characteristic consequences of hookah use.
Indoor Passive Exposure
Hookah smoke (and aerosol) increases indoor pollutants, particularly PM2.5, with levels detectable even in adjacent rooms. Therefore, smoke-free area policies are recommended to include both hookah and electronic products.
What Do Electronic Heated Alternatives Offer?
When charcoal is not used, charcoal-derived CO and combustion products decrease dramatically. An experiment using an automatic smoking machine found that with electric heating elements (EHE), CO emissions dropped by ~90% and PAHs by ~80%; however, some irritants such as acrolein were higher in certain setups, indicating that design and temperature control are critical. Check out the official test video and report.
A 2025 study further emphasized that the primary source of waterpipe aerosol pollution is charcoal combustion or tobacco roasting by charcoal, and that electronic heating can reduce or eliminate this pollution.
Conclusion: Why Are Charcoal-Free (Electronic) Hookahs a Healthier Alternative?
The scientific picture is clear: Traditional charcoal-heated hookahs cause high exposure to CO and combustion-derived toxins, triggering risks ranging from acute symptoms to vascular dysfunction. When charcoal and combustion are eliminated, so is the source of CO. Indeed, some laboratory/product data report that CO is “undetectable” and that harmful chemicals (except nicotine) are on average 94% lower; independent experimental studies also confirm a ~90% reduction in CO. Therefore, electronic hookahs—free of carbon monoxide and combustion-related chemicals—are a healthier alternative compared to traditional hookahs.