PAHs are a group of chemicals that are formed the incomplete burning of coal, oil and gas, garbage, or other organic substances.

多环芳烃是一组化学物质，他们是由未经完全燃烧的煤。油和气。垃圾。或是其它有机物质形成的。

youdao

Aiming at the facts of low temperature, rare oxygen and low-pressure, ameliorates phenomena of burner igniting difficulty , unsteady flame and incomplete burning by improving on burner's parts.

针对高原地区低温、缺氧、气压低的客观现实，通过对轻油燃烧器结构的改进，解决了燃烧器点火困难、火焰不稳定及燃烧不完全问题；

youdao

The academics advocate concentrating first on short-term fixes for greenhouse gases or other warming agents, such as black carbon - particles emitted from the incomplete burning of fossil fuels, principally in diesel engines and wood stoves.

BBC: Academics urge radical new approach to climate change