| Partial-Bypass Filter | A filter that removes some contaminants from the air, but allows some air to pass through without contacting the filter, usually to minimize the resistance to airflow. |
| Particle Board | Made from small softwood particles that resemble coarse sawdust, and is usually held together with potent urea-formaldehyde (UF) glue. |
| Particulate Filter | An air filter designed to remove particulates from the air. |
| Particulates | Solid (or liquid) air pollutants, as opposed to gases. |
| Parts Per Millon (ppm) | A small unit of measurement, often used to express the concentration of pollutants in the air. |
| Pascal | The pascal (Pa) or kilopascal (kPa) is a unit of pressure measurement. |
| Pascal (Pa.) | A small unit of pressure measurement, useful in diagnosing houses for tightness and ventilation. One pound per square inch (psi) equals about 7,000 Pascals. |
| Pass-Through | An opening between two rooms through which air can move when pressure imbalances occur between the rooms. |
| Passive Solar | A home-energy alternative or addition to gas and utility electric. |
| Passive Ventilation | Caused by house pressurization or depressurization, not directly caused by a fan. Infiltration and exfiltration involve passive air movement. |
| People Pollutants | Solids, liquids, and gases given off by humans as a normal part of the life process. |
| Perchlorate | As a pollutant, perchlorate is found in groundwater, surface water and soil and has proven to be a pervasive contaminant of agricultural and manufactured food products. |
| Permanent-Split-Capacitor Motor | A type of electric motor characterized by a main winding and an auxiliary winding wired in series with a capacitor. |
| Permeable Wall | An insulated part of a house’s structure through which outdoor air can pass from the outdoors to the indoors and is tempered in the process. |
| Personal Health Record (PHR) | A Personal Health Record (PHR) is a tool that enables you to collect, manage and share past and current information about your health or the health of someone in your care. |
| Pesticides | Chemical compounds formulated to kill living creatures. |
| Phosphates | Once widely used to soften water for use in washing machines, some makers have reduced use of these chemicals. |
| PicoCurie per liter (pC/l) | A unit of measurement used to determine the concentration of radon in the air. |
| Pier Foundations | Often used in hot, humid climates, a pier foundation lifts a house up off the ground reducing health hazards from direct soil contact. |
| Plywood | Material made of several layers of wood glued together, which is widely used in home construction. |
| Poly Moisture Barrier | Sheets of heavy plastic that help keep moisture out. |
| Polyurethane and polyisocyanurate | Polyurethane can be a flexible foam, as used in upholstery, or a rigid foam, as in insulation.
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| Porosity | Capacity of a material to be penetrated through its pores, for example, by gases or vapors. |
| Positive Pressure | When the air pressure inside a house or room is greater than the atmospheric pressure outside the house or room. |
| Pounds per square inch (psi) | A unit of pressure measurement. |
| Pressure Washer | They’re great outdoor cleaning tools, but they can cause severe injury or damage if misused. |
| Pressurization | When the air pressure inside a house or room is greater than the atmospheric pressure outside the house or room. |
| Preventive Maintenance | A preventive, systematic approach to health, safety and comfort is a homeowner’s best defense against poor air quality, unexpected breakdowns and expensive repairs. |
| Protective Gloves | Keep your hands (and, sometimes, forearms) safe from bacteria, spores or caustic chemicals. |
| Psychometric Chart | A graph used to determine the moisture content and energy of air at different temperatures. |
