Honda CBR 125RW 2007 Owner's Manual page 186

Emission Control Systems
Source of Exhaust Emissions
The combustion process produces carbon
monoxide (CO), oxides of nitrogen (NOx),
and hydrocarbons (HC). Control of
hydrocarbons and oxides of nitrogen is
very important because, under certain
conditions, they react to form
photochemical smog when subjected to
sunlight. Carbon monoxide does not react
in the same way, but it is toxic.
Honda Motor Co., Ltd. utilizes various
systems to reduce hydrocarbons, oxides of
nitrogen, and carbon monoxide.
176 Technical Information