A method, system, and apparatus for sensing gases includes a gas detector with at least one light emitter and at least one light detector configured to detect an intensity of light at wavelengths of light indicative of target gas(es). The system also includes a processor circuit and a data storage device in communication with the gas detector and configured to determine an amount of target gas in the volume of the gas-air mixture and to determine a lower explosive limit (“LEL”) level for at least one target gas in the gas-air mixture. The processor is configured to receive data regarding temperature and relative humidity of the gas-air mixture such that the processor circuit can adjust the LEL according to the temperature and humidity. Temperature and humidity sensors may be included to sense these conditions for inputting to the processor.