The implementation standard of non-methane total hydrocarbons in ambient air draws lessons from the Israeli standard of 2.0mg/m3. After the reform, the standards implemented in different places are different, depending on the local standards.

Residual value of non-methane total hydrocarbon (NMHC) after deducting methane from the total hydrocarbon determination results; However, total hydrocarbons are the sum of gaseous organic compounds that respond on the gas chromatography hydrogen flame ionization detector under specific conditions.

Generally speaking, NMHC refers to all volatile hydrocarbons (mainly C2 ~ C8) except methane. But this understanding is not practical.

Extended data:

There are many methods to monitor non-methane total hydrocarbons in ambient air and industrial waste gas, but most countries use gas chromatography. The contents of total hydrocarbons and methane were determined by gas chromatography with double-column dual-hydrogen flame ionization detector.

The difference between them lies in the content of non-methane total hydrocarbons. The total non-methane hydrocarbons measured under specified conditions have obvious response in the gas chromatography hydrogen flame ionization detector, and the total hydrocarbons except methane are calculated by carbon.

The anthropogenic sources of non-methane total hydrocarbons mainly include gasoline combustion, incineration, solvent evaporation, oil evaporation and transportation loss, and waste refining, accounting for about 96% of the anthropogenic emissions of hydrocarbons.

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