Secondary organic aerosol formation for the reaction between ozone and limonene (emitted from lemon skin).

1 - A UV light is turned on to produce ozone from oxygene
2 - A green laser is used to check that no (or little) aerosol is present in the glass flask
3 - A piece of lemon skin is introduced in the flask
4 - The aerosol appears like a very thin fume that will now scatter the beam of the laser