PPM Methane Regulatory Limits

Updated November 22, 2016

Methane gas is readily supplied as a part of natural gas. Methane is highly flammable under various conditions. Currently, no data or studies prove that there is an exposure limit that is harmful to human health. The Occupational Safety and Health Administration (OSHA) does not have a permissible exposure limit (PEL) in parts per million (PPM), however the Canadian equivalent lists a general exposure limit on its website.


Methane is a naturally occurring chemical compound. Its chemical formula is CH4, four hydrogen atoms bonded to one carbon atom. Methane is a member of the family of compounds called aliphatic hydrocarbons. Methane is naturally found as the primary component of natural gas, 50 per cent or more. Methane occurs naturally as a gas, but it can be compressed into a liquid. It has no colour or odour. Manufacturers of methane gas often add an artificial smell for safety.

Exposure Limits

Although OSHA does not list a specific exposure limit for methane, the Canadian Centre for Occupational Health and Safety lists 1,000 PPM as the time-weighted average exposure limit for people. Time-weighted average PPMs are generally collected over an eight-hour period. If the total exceeds 1,000 PPM over that time, this would be considered dangerous to human health. However, studies from the 1970s indicated that exposure levels up to 10,000 PPM did not have a toxic effect on humans.

Safety Issues

Although there is no evidence available to indicate methane is toxic to humans, inhaling it will cause oxygen levels in the body to decrease. Continued inhalation of methane will cause dizziness, nausea or unconsciousness. Since untreated methane does not have an odour, you may not know if it is in your environment. In addition, methane is a highly combustible gas. Small amounts of it can ignite in air, or from a small static charge. Extreme caution should be utilised when dealing with methane gas. Open flames or smoking will cause ignition.

Production and Uses

Methane is most commonly found as a component in natural gas. It is also made by the distillation of coal in coke ovens. The primary use of methane is in natural gas to heat homes and run appliances. Other chemicals or products derived from methane include ethanol, carbon black, methanol and chloroform.

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