You know the smell—that unmistakable rotten egg odor. We all count on it to warn us of natural gas leaks. But is that sharp, eye-watering scent enough to protect us from the health risks that come with natural gas exposure?
According to a recent study, the answer is no.
That familiar stink isn’t the gas. Natural gas is mostly methane—a colorless and odorless gas—so sulfuric odorants, typically a chemical called mercaptan (methanethiol), are added to help consumers detect gas leaks. This new study on these odorants and air pollutants in natural gas revealed some glaring issues with relying solely on our noses to recognize leaks. Critically, sense of smell varies widely from person to person. Adults over 70 may have diminished smelling abilities, as do those of us who have been affected by COVID-19. The study also revealed that different geographic regions use varying concentrations of these natural gas odorants. In some areas, the odor is strong and noticeable, while in others, it’s much fainter.
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Researchers also discovered that small gas leaks can introduce hazardous air pollutants like benzene, a known carcinogen, into the air. Small gas leaks frequently go undetected for a number of reasons, including that they’re often undetectable by smell. Startlingly, almost every sample taken from gas stoves in nearly 500 residences across 17 North American cities contained benzene. Although all the regions studied had natural gas with enough added odorant to alert people to big leaks that could lead to high benzene exposures or explosion hazards, smaller, undetected leaks still elevated ambient pollutants in residences.
Benzene and methane can even slip past people with an average sense of smell. The study found factors like city, residence size, and ventilation also impacted people’s ability to detect leaks. While ventilation is typically encouraged to prevent pollutants from becoming too concentrated, researchers found that ventilation can have unintended consequences. Increased air flow can actually cause leaks to go unnoticed. Larger residences with higher ventilation, for example, can dilute leak odorants, allowing larger leaks to evade detection compared to smaller residences with poorer ventilation. It’s a double-edged sword.
The fact that natural gas appliances leak and contribute to health harms like increased pediatric asthma cases isn’t news. This recent study not only reinforces the presence of gas leaks, but also raises new concerns that smell, our primary method of detecting gas leaks, might not be reliable enough.
So, what can be done?
- Change policy. Researchers recommend adopting stricter odorization policies in the U.S. and Canada, similar to the EU, which has higher minimum odorization levels.
- Adopt detectors and sensors. Making gas leak detectors as common as smoke or carbon monoxide detectors could help. Researchers suggest requiring them in all buildings with gas appliances. Additionally, real-time, highly sensitive methane sensors could detect smaller leaks that noses might miss.
- Raise awareness. People need to know that sense of smell, while useful, is far from foolproof when it comes to detecting natural gas leaks. Humans aren’t detectors or sensors.
With hazardous pollutants like benzene slipping past people with an average sense of smell unnoticed, it’s clear that we need to rethink our approach to gas safety. By advocating for stronger odorization standards and implementing advanced detection technologies in homes with gas stoves, we can better protect ourselves and our families from the hidden dangers lurking in our indoor air. Ultimately, transitioning to clean energy is essential for eliminating these risks altogether, and ensuring a safer, healthier future for everyone.
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