Unicode has dedicated code-pointsU+33A9㎩SQUARE PA andU+33AA㎪SQUARE KPA in theCJK Compatibility block, but these exist only for backward-compatibility with some older ideographic character-sets and are thereforedeprecated.[12][13]
The pascal (Pa) or kilopascal (kPa) as a unit of pressure measurement is widely used throughout the world and has largely replaced thepounds per square inch (psi) unit, except in some countries that still use theimperial measurement system or theUS customary system, including the United States.
Geophysicists use the gigapascal (GPa) in measuring or calculating tectonic stresses and pressures within theEarth.
The pascal is also equivalent to the SI unit ofenergy density, the joule per cubic metre. This applies not only to the thermodynamics of pressurised gases, but also to the energy density ofelectric,magnetic, andgravitational fields.
The pascal is used to measuresound pressure.Loudness is the subjective experience of sound pressure and is measured as asound pressure level (SPL) on a logarithmic scale of the sound pressure relative to some reference pressure. For sound in air, a pressure of 20 μPa is considered to be at thethreshold of hearing for humans and is a common reference pressure, so that its SPL is zero.
In medicine, blood pressure is measured inmillimeters of mercury (mmHg, very close to oneTorr). The normal adult blood pressure is less than 120 mmHg systolic BP (SBP) and less than 80 mmHg diastolic BP (DBP).[16] Convert mmHg to SI units as follows:1 mmHg =0.13332 kPa. Hence the normal blood pressure in SI units is less than 16.0 kPa SBP and less than 10.7 kPa DBP. These values are similar to the pressure of water column of average human height; so pressure has to be measured on arm roughly at the level of the heart.
The units of atmospheric pressure commonly used inmeteorology were formerly thebar (100000 Pa), which is close to the average air pressure on Earth, and the millibar. Since the introduction ofSI units, meteorologists generally measure atmospheric pressure in hectopascals (hPa), equal to 100 pascals or 1 millibar.[17][18][19][20][21][22][23] Exceptions include Canada, which uses kilopascals (kPa). In many other fields of science, prefixes that are a power of 1000 are preferred, which theoretically excludes hectopascal from use.[24][25]
Many countries still use millibars to measure atmospheric pressure. In practically all other fields, the kilopascal is used instead.[26]
