Airborne Particle Mass
A BRIEF HISTORY OF AIRBORNE PARTICLE MATTER
Airborne particle matter (PM) in the outdoor environment has been studied by the EPA and other agencies for over thirty years. Only recently has the research turned to the indoor environment - at first in the industrial setting and in the past few years in residential settings. Download a brochure entitled Particle Pollution and Your Health from the EPA.
Indoor air quality assessments of residential properties have become much more reliable in large part due to the advances of a device known as an airborne particle counter. Handheld computer-driven units like the one shown at the right have become more affordable and air quality professionals have learned how to read and interpret the data the device produces. As a result, homeowners can benefit from extensive airborne particle mapping of the inside of their home. Air quality issues that were once difficult and expensive to trace are much easier to locate with a particle counter. In fact, many experts believe that airborne particle counters are a more important tool than a spore trap and air pump for determining levels of airborne fungi.
WHY AIRBORNE PARTICLE MASS IS SO IMPORTANT
The chart above shows how airborne particle mass above carpeted surfaces increased significantly over a seven-hour school day while the PM on tile varied somewhat and outdoor PM dropped over the course of the day.
Indoor and outdoor air currents carry fine and ultrafine particles that include pieces of biologicals (such as insect parts, skin fragments, bacteria & fungal spores), volatile organic compounds (VOCs) that are naturally sourced but potentially explosive chemicals (such as formaldehyde and benzene), and non-organic chemicals that are assembled in a lab. These particles are so small that they cannot be seen by the human eye, but they can be sensed via smell and how they affect the respiratory system. They are also detectable by the laser and electronics inside the airborne particle counter.
Elevated levels of PM have been shown to cause a variety of respiratory and cardiovascular issues, including high blood pressure, increased heart rate, and decreased pulse pressure. Researchers have found the effects to be so severe in the elderly population that premature death is one of the symptoms of high airborne PM. Moreover, current university research is focusing on the new compounds that are formed when inorganic chemicals attach to organic particles. While the research is ongoing, preliminary data suggests that these new compounds may have a profound effect on the health of humans and pets such as cats and dogs.
Click to read our January 2013 blog post, Musings of a Particle Nerd
THE ROLE OF PARTICLE MASS IN EVERY IAQ SURVEY CONDUCTED BY ESG
Particle mass readings are collected by ESG investigators at every IAQ assessment along with readings for VOCs, gases, relative humidity and temperature. The real-time readings for all of these constituents are gathered using GrayWolf Sensing Solutions test equipment shown at the left. Any potentially life-threatening data is shared with the client in a timely fashion. In all cases, the data is downloaded from the handheld computer used on site into a desktop computer where it is formatted and color-coded in an Excel spreadsheet. The spreadsheet and an interpretation are provided to the client within 24 hours of the assessment.
ESG investigators have used the PM readings to isolate hidden contamination in wall and floor cavities, under stairs, and in inaccessible areas in a variety of structures. Some examples of how airborne particle mass readings have helped clients are listed below:
- hidden microbial contamination was identified in a bedroom closet wall cavity when the airborne PM spiked in the bedroom;
- an unexplained odor was identified as coming from the crawl space underneath a family room;
- clean-looking air supply ducts were found to be supplying dirty air to a hospital room;
- an assisted living center resident was found to be sneaking cigarettes while outdoors (no smoking is allowed at the center). The odor was not noticeable on clothes but the PM spiked when the offending resident entered the room;
- a contaminated office houseplant was identified as the culprit that was causing people who worked near the houseplant to feel ill;
- a child's bed was identified as the likely source of contamination that was making the child sick;
- upholstered office chairs were identified as the likely source of contamination in a conference room where people were feeling sick during meetings