Asphalt kulul waxa uu sii daayaa gaasas inta badan ka kooban hydrocarbons kala duwan, gaar ahaan hydrocarbons caraf udgoon polycyclic.
Halabuurka asphalt waxaa ka mid ah asphaltene, xabagta, hydrocarbons cufan iyo caraf udgoon.
Sababtoo ah daaweynta heerkulka sare ama uumiga dheer ee dabiiciga ah, batroolka, iyo Daamurka dhuxusha, Habka kuleylku wuxuu abuuraa walxo yar yar oo kelli ah, ugu horrayn silsilad dheer iyo hydrocarbons caraf udgoon, Unugyada muhiimka ah sida naphthalene, anthracene, phenanthrene, iyo benzo[a]pyrene.
Hydrocarbons aromatic polycyclic ayaa si gaar ah sun u ah qaarna waa kansarrada la yaqaan.