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Terms starting with P
Definition
“PM” (Particulate Matter) is not a single pollutant but refers to a complex mixture of solids and aerosols. Which are of varying shapes, sizes, and chemical compositions. Which may contain many chemical species like organic compounds, inorganic ios, metallic compounds, elementary carbon, etc. These atmospheric particles are definable by their diameter for air quality regulatory purposes.
Passive air sampling is a method primarily used to sample for gases and vapors. In this case, passive air sampling is more accurately termed “diffusive sampling” because it relies on the natural process of diffusion. This method may be deemed “passive” because, unlike active sampling, it does not involve pumping air to collect it.
PCB (Printed Circuit Board): A PCB, or printed circuit board, is a fundamental component in electronic devices. It is a flat board made of non-conductive material, typically fiberglass, with electrical conductors and connections etched or printed onto its surface. PCBs provide a platform for mounting and interconnecting various electronic components, such as integrated circuits, resistors, capacitors, and connectors, to create functional electronic circuits. They are essential for the construction and assembly of electronic devices, from small consumer electronics to complex industrial systems.
A PCB controller is an electronic circuit that is used to control the operation of a printed circuit board (PCB). It typically contains a microcontroller, input/output (I/O) interfaces, and power circuitry. The controller can be programmed to monitor and control various functions within the PCB, such as data acquisition, signal processing, and power management. The controller is responsible for timing, sequencing, and controlling the operation of the PCB.
In a photoionization detector high-energy photons, typically in the vacuum ultraviolet (VUV) range, break molecules into positively charged ions. As compounds enter the detector they are bombarded by high-energy UV photons and are ionized when they absorb the UV light, resulting in ejection of electrons and the formation of positively charged ions. The ions produce an electric current, which is the signal output of the detector.
The ultra-fine inhalable particles that are less than or equal to 1 micrometer in diameter are collectively known as PM1. They are more than 400 times thinner than human hair (too small to be detectable by the human eye) that can penetrate directly through the lungs into the bloodstream when inhaled.
The inhalable particles that are less than or equal to 10 micrometers in diameter are collectively known as PM10, they tend to settle as they are heavier. Once released, they stay in the air for minutes or hours and travel as little as 100 meters to 50 kilometers. Also, examples of such coarse particles include construction dust, pollen, mold, etc.
The particulate matter that is less than or equal to 100 micrometers in diameter is collectively known as PM100. They are also known as “inhalable dust”. This fraction of the particulate matter can enter the nose and/or mouth while breathing. Deposition takes place in the air passages between the mouth, the nose, and the larynx. Once released into the atmosphere, they tend to settle as they are heavier. Examples include wood particles, dust, etc.
“The fine inhalable particles that are less than or equal to 2.5 micrometers in diameter are collectively known as PM2.5. They are more than 100 times thinner than a human hair (too small to be detectable by the human eye) making them more harmful than larger particles as they can penetrate deeper into the human respiratory tract when inhaled.
PM2.5 in the atmosphere consists of toxic organic compounds and also heavy metals released from various sources. Once released, they stay in the air for a long time i.e. days or weeks and can travel hundreds of miles.”
The inhalable particles that are less than or equal to 10 micrometers in diameter are collectively known as PM10, they tend to settle as they are heavier. Once released, they stay in the air for minutes or hours and travel as little as 100 meters to 50 kilometers. Also, examples of such coarse particles include construction dust, pollen, mold, etc.
The pollution rose is basically another means of illustrating the frequency distribution of wind direction temporally correlated with a chosen pollutant.
“Parts per billion (ppb) is a unit of measurement used to express the concentration of a substance in a mixture, typically in gases or liquids. It signifies the ratio of the quantity of a particular substance to the total quantity of the mixture, with the substance being present at one part per billion.
Mathematically, ppb is defined as:
Ppb = 1 \1,000,000,000parts
In other words, 1 ppb represents one part of the substance in every billion parts of the mixture. This unit is commonly used in environmental science, chemistry, and air quality monitoring to specify very low concentrations of pollutants or trace substances in the atmosphere or other media. It is particularly useful for quantifying substances that are present in extremely small amounts.
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“Parts per million (ppm) is a unit of measurement used to express the concentration of a substance in a mixture, typically in gases or liquids. It signifies the ratio of the quantity of a particular substance to the total quantity of the mixture, with the substance being present at one part per million.
Mathematically, ppm is defined as:
1 ppm = 1 \1,000,000 parts
In other words, 1 ppm represents one part of the substance in every million parts of the mixture. This unit is commonly used in various fields, including chemistry, environmental science, and industry, to specify relatively low concentrations of substances. It is particularly useful for quantifying substances that are present in small amounts, but not at trace levels.
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Precision refers to how well a set of sensors reproduces the measurement of a pollutant under identical conditions (e.g., same concentration and temperature). Variation around the mean of a set of measurements obtained concurrently by two (2) or more sensors of the same type collocated under the same sampling conditions. The consistency in measurements from identical sensors is often quantified by standard deviation (SD) or the coefficient of variation (CV), with lower values indicating a more precise measurement.
A primary pollutant is an air pollutant emitted directly from a source.
A power-swing blocking (PSB) function is available in modern distance relays to prevent unwanted distance relay element operation during power swings. The main purpose of the PSB function is to differentiate between faults and power swings and block distance or other relay elements from operating during a power swing.
