I’m finding icky-like particles in my home

I am a stay at household mom, then i decided to stay household with my children about two years ago when our youngest child was born, and my friend and I thought it was best that I stay household with our two children since my friend and I didn’t want to search for a babysitter! Plus my friend and I don’t want to pay for a babysitter everyday. My friend and I thought that that could get a little costly, however when my children and I are household together I make sure that my oldest child, who is going into pre k next year, is learning. I will show her flash cards with numbers and words and I’ll teach her how to write the alphabet. I think this will be legitimately beneficial for her before she starts university. While I was teaching my child on the floor I saw some black soot on my end table in my home office. I stopped our teaching session and looked at the other surfaces in my home, there was soot everywhere too. It looks like there is pepper all over my furniture. My furnace has been on for most of the afternoon however I’m confused as to why there’s soot. It seems a little hazardous because my friend and I are breathing this in. I decided to call my Heating, Ventilation and A/C provider to schedule an appointment with a specialist. While I was waiting for him I decided to turn my Heating, Ventilation and A/C system off. I’m hoping that it’s just my HVAC ducts needing a cleaning and not some major repair… Hopefully there’s a solution so there’s no more soot circulating in our home.
air conditioning company