Methane (CH₄)

Description:

Methane (CH₄) is a flammable, colorless, and odorless gas belonging to the hydrocarbon group. It is also known as methyl hydride. Methane is the simplest member of the alkane family. Methane burns with low soot formation, producing carbon dioxide and water. Along with carbon dioxide (CO₂), methane is one of the most significant greenhouse gases, contributing significantly to climate change. As a naturally occurring chemical compound, methane is the main component of natural gas and serves, among other things, as an energy source and raw material for technical syntheses.

Methane limit values:

Since methane is virtually non-toxic to humans, no national or international exposure limits have been established for this gas.

Although methane poses comparatively few health concerns for humans, excessively high concentrations are not without risks. In particular, methane’s high flammability represents a significant risk. A methane concentration of 29 g/m³ is considered the lower explosive limit (LEL). This means that starting at a methane concentration of 4.4% vol. (volume percent) in the air, flame propagation in the gas mixture occurs completely spontaneously upon ignition, triggering explosions.

Consequences of a concentration that is too high or too low:

Methane is, in principle, a non-toxic gas that is only slightly narcotic. However, at higher concentrations, it can cause breathing difficulties, increase respiratory and heart rates, and lead to low blood pressure accompanied by dizziness and lightheadedness. The resulting lack of oxygen can also affect the central nervous system, causing drowsiness, numbness in the arms and legs, as well as mental confusion and memory loss. However, these effects do not typically cause permanent damage, although they significantly impair health and performance, for example in work environments. Due to the displacement of oxygen, there is nevertheless a risk of asphyxiation at very high concentrations.

If the concentration of methane in the air reaches between 5 and 15 percent, an explosive mixture forms. If sources of ignition are also present—such as open flames, sparks, hot surfaces, electricity, or electrostatic charges—there is an increased risk of explosion. In addition to severe burns, heating methane also produces hazardous gases such as carbon monoxide.

Source of CH₄:

Methane is constantly formed through biological and geological processes. It is generated by high temperatures and pressure in the Earth's deeper layers and is often released into the Earth's atmosphere through volcanic activity.

During the decomposition of organic matter in the absence of air, microorganisms emit methane, among other things. Plants and animals also produce methane, which they release into the environment.

Of the 500 million metric tons of methane emitted each year, 70% is due to human activity. In particular, livestock farming and crop cultivation contribute to the increase in the proportion of methane in the air we breathe. Cattle farming alone accounts for 39% of emissions, and flooded rice cultivation for 17%.

In addition, the transportation sector, the extraction and production of fuels (such as coal and natural gas), oil refining, the production of iron, steel, and malleable cast iron, as well as the treatment of waste, wastewater, and sewage sludge, all make a significant contribution.

Sensor used:

Methane is measured using a sensor based on infrared absorption. The advantage of this principle is its very long service life compared to an electrochemical sensor and the virtual absence of cross-sensitivity. The disadvantage is a slightly higher price.

Measuring methane:

It measures methane levels, components, and indoor air pollutants in real time to improve your health and performance. You can order the air-⁠Q as an air quality monitor here.