Healthy Indoors Magazine
Issue link: https://hi.healthyindoors.com/i/815664
MAY'S WAYS — March/April 2017 20 Testing leak at return with smoke pencil May Indoor Air Investigations LLC In newer, tight houses, just turning on an ex- haust fan in the kitchen can reverse the direction of airflow at a chimney flue. In older houses that aren't as tight, wind direction at the exterior can affect airflows indoors. If the wind is blowing against one exterior wall, exterior air will flow into that wall cavity through construction cracks and other openings. The wall cavity will then be- come pressurized, and air will flow from that cavity into the room. The room will become pressurized, and air will flow from that room into adjacent spaces. What's this got to do with indoor air quality? Air flowing indoors can carry pleasant odors from room to room and level to level. If someone is cooking bacon in your kitchen, air can carry that aroma to another person who is on the second floor (and get them out of bed fast in the morning). And if someone in a bedroom puts on a liberal amount of perfume, people can smell the perfume before the person even enters another room. But odors can also be problematic for some people who are sensitized to some vapors – such as fragrances. Air can carry sewer-gas odors if there is a toilet somewhere with a loose toilet seal, and no one that I know enjoys THAT odor! Cigarette smoke is also carried on airflows. We get a few calls every month from people who live in apartments or condos where they can smell their neighbor's fragrances or cigarette smoke. It's extremely difficult to prevent air from flowing from common hallways into units, and thus non-smok- ers can be exposed to second-hand smoke be- cause their neighbors who are alongside or even several floors beneath them are smokers. And as we all know or should know, cigarette smoke contains many toxins, including formaldehyde, carbon monoxide and hydrogen cyanide. It also Y ou may not think of air as "matter" in the scientific sense, but air IS matter. Like water, air is a fluid that flows. We know this instinctively when we stand outside, see and hear leaves rustling in the wind, and feel that wind on our faces. Wind is the physical confirmation that air moves or flows. Air also flows within buildings. Warmer air is less dense than cooler air, so warm air rises and cool air sinks. And just as water flows downhill, air moves from higher pressure to lower pressure. Untie a filled balloon and most of the air flows out. Air also flows from outdoors to indoors, and from indoors to outdoors. Operation of a heating or cooling system with a leaky return duct can lower the air pressure in a basement. Then, soil gases (including mois- ture and radon) can be drawn into the basement through concrete-slab and foundation-wall cracks. Those gases will replace the air that would have flowed from the upstairs into the system. Then, the upstairs may become pressurized, forcing in- door air above the basement into openings in wall cavities or into an attic. Particles Matter Air is matter that flows. ©2017 Jeffrey C. May