Formaldehyde and benzene are to volatile to condense onto or absorb into PM2.5 particles. Cooking oil particles can contain other toxic compounds formed during heating, including polycyclic aromatic hydrocarbons (PAHs), acrolein, and various aldehydes and ketones. If formaldehyde or benzene react to form less volatile products, those reaction products might become part of particulate matter, but they're no longer formaldehyde or benzene at that point. So while cooking emissions do produce both harmful VOCs and harmful PM2.5 simultaneously, they remain distinct categories of pollutants.