Alkenes - molecules with one or more double bonds - include molecules like a-pinene and terpinolene, which are responsible for the smells of pine trees, orange groves and many household cleaning products. Through experiments in the EUPHORE simulation chamber, we have shown that they are incorrectly detected as NO and NO2 in common air quality monitors - with potentially significant impacts in forest environments, and for indoor air chemistry.
Alam et al., Interference from alkenes in chemiluminescent NOx measurements, Atmos. Meas. Tech., 2020