all vehicles burn fuel to move and everything that comes out of the exaust pipe are the emissions of the burnt fluid.
The emissions are mainly nitrogen, carbon dioxide, NOx, water vapour and unburned hydrocarbons
the catalytic convertor
to help reduce air pollution
Hydro carbons, oxides of nitrogen and carbon monoxide. HC, NOx, and CO
you can not adjust emissions there may be a fault if your exhaust is leaking or your oxygen sensor (lambda sensor) is faulty maybe a injector leaking fuel into the cylinder may even be a coil pack or...