“I don’t have a gas leak. I don’t smell anything.”
Regular gas inspections are crucially important for every homeowner or property manager. In many cases, they are required, like in the case of LL 152, where residential properties of 3 or more units are required to obtain a gas inspection every 4 years for safety.
Yet the reality is that every property needs to strongly consider a gas inspection, if not every year than every other year. Even those waiting for an LL 152 inspection may want to consider an extra one here and there to make sure that things are safe.
And no, smell alone is not enough.
Most people are taught from a young age to associate the smell of “rotten eggs” with a gas leak. That scent comes from a chemical additive called mercaptan, which is added to otherwise odorless natural gas to make leaks easier to detect. But relying entirely on smell to identify a residential gas leak is not always reliable or safe.
There are many scenarios in which a person may not be able to smell a gas leak, despite one being present. That’s why gas leaks should never be assumed to be detectable based on smell alone.
Why a Gas Leak Might Not Be Noticeable by Smell
Even though mercaptan is designed to be noticeable, various conditions can make a gas leak difficult or even impossible to detect through smell. These situations can be influenced by environmental factors or individual differences.
Several reasons a gas leak may not be detectable by smell include:
- Diminished Sense of Smell – Age, certain health conditions, medications, or recent illnesses like COVID-19 can temporarily or permanently reduce a person’s ability to detect odors.
- Gradual Buildup – A slow or low-volume leak may allow the nose to acclimate to the smell, making it less noticeable over time.
- Competing Odors – In kitchens or basements where strong odors are already present, the smell of mercaptan may blend in or go unnoticed.
- Absorption by Materials – Porous materials like carpeting, insulation, or drywall can sometimes absorb the odorant, reducing its detectability.
- Faulty Gas Supply – On rare occasions, the gas may not be properly odorized when supplied, especially if there is a malfunction or procedural error during distribution.
For these reasons, it is important not to rely solely on your sense of smell when determining if there is a gas leak in your home.
Other Signs That Could Indicate a Gas Leak
Even in the absence of a noticeable odor, there may be other signs that suggest a gas leak. These can be physical, visual, or mechanical in nature.
Look out for the following:
- Hissing sounds near a gas line or appliance.
- Dead vegetation or unexplained brown patches near underground gas lines.
- Unusual air movement or dust blowing from the ground without wind.
- Higher-than-normal gas bills that don’t match usage.
- Physical symptoms like headaches, dizziness, nausea, or fatigue that worsen when at home and improve when away.
These symptoms may indicate the presence of natural gas, carbon monoxide, or another byproduct of a malfunctioning gas appliance.
Why Detection Tools and Inspections Are Still Necessary
Because natural gas leaks are not always detectable by smell, modern residential safety includes other precautions. Gas detectors and carbon monoxide alarms provide a layer of protection that goes beyond the limitations of human senses. In addition, routine inspections such as NYC’s Local Law 152 gas line inspections are intended to catch defects and prevent leaks before they pose a hazard.
Smell Is Not a Guarantee
While the odorant in residential gas is an important safety feature, it should not be treated as the only line of defense. Gas leaks can and do go unnoticed by smell alone. That’s why it is critical to remain attentive to other signs, follow inspection requirements, and consider installing gas detection systems in homes where gas appliances are in use.