Air Duct Cleaners

I work in a high rise building.The office windows cant be open.There is so much of dust.How is this possible?

Angel asked: The building management says the air-cond ducts are clean.Dryer Vent Cleaning Maryland

should i clean my forced hot air furnace myself or hire someone?

m t asked: how much more will a technician do when they service my furnace. last time i changed the oil filter, changed the nozzle, brushed and vacuumed, fixed some of the duct work, etc..i haven’t had time to get around to it. should i just hire someone? How much more will they do? run [...]