I have had the pleasure over the last few months of participating in one of the air-monitoring cohorts of ROCIS (Reducing Outdoor Contaminants in Indoor Spaces - http://rocis.org/). ROCIS is a small non-profit dedicated to understanding and finding simple ways to reduce indoor contaminants. As a participant I came home with a large cloth grocery bag filled with an assortment of air-quality monitors: I have two radon monitors, a CO2 monitor, carbon monoxide monitors, and a variety of small particle monitors from two different vendors interested in measuring small particles indoors and comparing them with the outdoor air. Participants are asked to keep a daily log of activities that they undertake at home that may affect the air quality in the house. I was curious to participate as I live near Nine Mile Run, close to Frick Park in Pittsburgh, Pennsylvania, but also very close to the overpass just near the Squirrel Hill Tunnel. I am down in a valley under heavily travelled Highway 376, and I had suspected for a long time that my air-quality was not wonderful.
I have learned from sitting in on some of the ROCIS meetings that air-quality in Pittsburgh is very poor. While our city has cleaned up its act from the height of the era of steel production (when we were known as “the smoky city”) we actually have air-quality that is still alarmingly poor. Unfortunately, it arrives in our city from other industrial regions many states away, so legislatively we are not in control of our "air-quality" destiny. Micro-fine particles blow across many miles and over our city. The problem with the micro-fine particles is that they are small enough to enter the bloodstream. These particles are related to a variety of serious health conditions including heart attack and stroke, and are responsible for an astounding number of deaths in Pittsburgh alone.
I learned a great deal from weeks with the monitoring equipment from ROCIS. Some mornings I was fortunate enough to wake up and see a small particle count outdoors of as low as 300. But there were many mornings that I woke to find particle counts of 5,000. These numbers are at 5 am, so they are not the result of the commute and pollution from the traffic on 376. Though I have to admit that I could see spikes in outdoor pollution that related to traffic, I was really surprised at how poor the air-quality was without the traffic on random mornings throughout the cohort. Linda Wigington (http://rocis.org/meet-team), who is a master in a variety of topics on home building performance, and who patiently leads the participants through the process at ROCIS, advised us to check the air quality on a site called Air Now (https://www.airnow.gov/). So it was possible to see Pittsburgh’s particle count and compare it to the air around my house.
My log illustrated to me how daily activities affect air-quality. I saw spikes in particle counts when vacuuming, showering, washing and drying clothes, when the HVAC system turned on, and most of all cooking - and the spikes were significant. Cooking could easily send my small particle count from 200 to 10,000! Those particles would hang around my dining room and living room for hours. I realized that my recirculating range hood is junk- I will never put another one in any house again. To lower my counts, I stopped using my gas cooktop, and using a borrowed induction cooktop lowered my counts even more.
But the most shocking revelation was from a small particle-monitor in my bedroom. I had a reading of 20,000 small particles! What the heck was going on there?
I realized that it was likely the humidifier and called Linda. Now, keep in mind that I was breathing the air in my bedroom for 7 to 8 hours every night, and the humidifier was placed in my room because I thought the moist air would be healthier! Linda confirmed that they had seen high particle counts from humidifiers. She told me to clean the humidifier and to try distilled water. The humidifier was pretty clean, but the distilled water did the trick and lowered the count to the low 100s. The particles were all of the substances that we find in our water: chlorine, minerals, and other pollutants. So those particles were atomized and became airborne, and then were able to enter our bloodstream. After a week I looked at the growing pile of plastic bottles, and considered the trips running to the store to fetch distilled water, and pitched the humidifier. Ironically, the post-nasal drip that has plagued me for about a year and half, cleared up ... coincidence? Maybe, but I doubt it.
I want you to know that I have no particular fascination with particulate in the air, but I do care about the air-quality in the buildings that we design. As we tighten the envelope in buildings and rely on mechanical ventilation, the indoor air-quality becomes more important. The air-quality in Passive House is known to be superior and we are currently testing that out on several projects to verify that fact. Your house actually acts (or should act) like a large filter that reduces the particle count that you breathe. I can foresee in the not-too-distant future a time when you will consult your air-quality monitor before you open the window. I have learned that even my leaky house is a pretty good filter, and many days the air outside was much poorer quality than the air inside, because it runs through the filter on my HVAC system.
It seems incomprehensible that outdoor air is frequently more polluted than indoor air. Until we decide as a culture that air-quality does matter and we begin to address the pollutant sources, we will need to become more aware of the air that we are breathing in order to protect our health. Our homes and workplaces will be used to protect us by filtering small particles out of the air we breathe. Passive House fits the criteria for making this a possibility by air-sealing and ventilating at high rates to keep air clean.