We can test your air for methane in real time: 0 – 100% LEL (Lower Explosive Limit) and 0 – 100% by volume of sampled air.
Methane is an odorless and colorless gas that is non-toxic, yet can prove quite deadly as an asphyxiant (by displacing available oxygen) if the oxygen concentration is reduced to below approximately sixteen percent.
Of course, methane is quite flammable at even smaller concentrations in the air–as low as five percent of the total volume.
Methane can infiltrate building interiors that are near landfills, due to off-gassing of decomposing organic materials. The technology exists to capture and use the landfill methane to produce electricity, but may not be utilized by all landfills.
Some indications of exposure to methane are decreased night vision, headache, nausea, increased rate of respiration and pulse. Blood-oxygen saturation may be below ninety percent, even in asymptomatic or mildly symptomatic patients. Normal oxygen saturation is usually between ninety-six and ninety-eight percent; lower concentrations are considered dangerous.
With severe methane poisoning, symptoms may include decreased alertness, drowsiness, dizziness, fatigue, euphoria, memory loss, decreased visual acuity, cyanosis, loss of consciousness, dysrhythmias, myocardial ischemia, pulmonary edema, seizures, and eventually death. Blood-oxygen saturation may be eighty percent or lower.
For additional information:
NIH Library of Medicine – Methane
Project Drawdown – Landfill Methane Capture
Verywell Health – Understanding Oxygen Saturation
Wikipedia, The Free Encyclopedia – Flammability limit
Wikipedia, The Free Encyclopedia – Methane, Safety