The air contained adhesive, non-toxic polymer particles.
Last winter, I had some complaints with my furnace. Various rooms in the house felt slightly chilly and adjusting the thermostat had little effect. There were significantly more contaminants circulating in the air and accumulating on surfaces, forcing me to vacuum and dust far more frequently. I was convinced that the heating system was making more noise and supplying less warm air. I noticed that it was starting up more often and running for much longer cycles. An increase in my monthly energy bill convinced me to schedule repair from a local HVAC contractor. The technician inspected the furnace and found nothing beyond a slight buildup of dust on the mechanisms. He then tested the ductwork and discovered the source of the problems. Leaks at the seams and an abundance of tiny holes throughout the duct system were allowing approximately twenty percent of the conditioned air to escape. Since the pipes are installed inside walls, ceilings and the crawlspace, I had no idea how repairs would be possible without a major mess. The technician then explained a relatively new process called Aeroseal that targets flaws in the ducts from the inside. After blocking off the supply and return registers, the technician hooked up a machine that sent highly pressurized air into the system. The air contained adhesive, non-toxic polymer particles. As the air leaked out of imperfections, the particles clung to the edges, steadily built up and formed an airtight seal. The whole process was completed in a couple of hours and created no damage, fumes or mess. The technician verified the results by way of a computer program and provided a certificate for a ten-year guarantee.