Shenhai Kuphulika-Umboni
Zovala za asphalt zopanda madzi, yotengedwa mu mafuta, amapangidwa ndi osasinthasintha, ma hydrocarbons apamwamba kwambiri.
Makamaka pa kutentha kokwera, zokutira izi zimatulutsa utsi woyipa kuchokera kuzinthu zovulaza mkati mwa phula, zimakhudza kwambiri mpweya wa m'nyumba.