Methane (CH₄) is a colourless, odourless gas and one of the most important greenhouse gases. It is released from natural sources such as wetlands, as well as human activities including agriculture (especially livestock), waste management, and fossil fuel production.
Although methane is not directly harmful to human health at typical outdoor concentrations, it contributes significantly to climate change and plays a role in the formation of ground-level ozone. Monitoring methane levels helps track emissions and understand broader environmental impacts.