As a chemical engineer with extensive experience in the field of environmental and occupational health, I have a deep understanding of the properties and effects of various chemicals, including methane. Methane, commonly known as natural gas, is a colorless, odorless, non-toxic gas under normal atmospheric conditions. However, it can pose significant risks due to its flammability and potential to displace oxygen in the environment.

Methane is a simple asphyxiant, which means it can cause asphyxiation by displacing oxygen in the air. When methane is present in high concentrations, it reduces the amount of oxygen available for breathing, which can lead to suffocation and death if not addressed promptly. This is particularly a concern in enclosed spaces where the gas can accumulate and displace the breathable air.

It is important to note that methane itself does not have a direct toxic effect on the human body. However, the lack of oxygen due to methane's presence can lead to hypoxia, a condition where the body is deprived of adequate oxygen supply. Symptoms of hypoxia can include shortness of breath, rapid breathing, confusion, and in severe cases, unconsciousness and death.

Moreover, methane is a potent greenhouse gas, contributing to climate change when released into the atmosphere. Its global warming potential is much higher than that of carbon dioxide, although it has a shorter atmospheric lifetime.

In terms of occupational safety, methane does not have an OSHA Permissible Exposure Limit (PEL) because it is not considered directly toxic. However, the Occupational Safety and Health Administration (OSHA) does have regulations in place to ensure that workers are not exposed to oxygen-deficient atmospheres, which can occur in environments where methane is present.

The flammability of methane is another critical concern. It can ignite and explode when mixed with air at certain concentrations. The lower explosive limit (LEL) for methane is 5%, and the upper explosive limit (UEL) is 15%. This means that if methane is present in the air at concentrations between these two percentages, it can ignite and potentially cause an explosion if an ignition source is present.

To mitigate the risks associated with methane, it is essential to implement proper safety measures. This includes ensuring adequate ventilation in areas where methane may be present, using gas detectors to monitor methane levels, and providing appropriate training to workers on the dangers of methane and how to respond in case of a release.

In summary, while liquid methane is not considered poisonous in the traditional sense, it can pose serious health and safety risks due to its asphyxiant properties and flammability. It is crucial to handle and store methane with care and to follow all safety guidelines to prevent accidents and ensure the well-being of individuals in the vicinity.

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Methane gas is relatively non-toxic; it does not have an OSHA PEL Standard. Its health affects are associated with being a simple asphyxiant displacing oxygen in the lungs. ... Methane is extremely flammable and can explode at concentrations between 5% (lower explosive limit) and 15% (upper explosive limit).read more >>