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  2. Lapse rate - Wikipedia

    en.wikipedia.org/wiki/Lapse_rate

    Adiabatic processes for air have a characteristic temperature-pressure curve. As air circulates vertically, the air takes on that characteristic gradient. When the air contains little water, this lapse rate is known as the dry adiabatic lapse rate: the rate of temperature decrease is 9.8 °C/km (5.4 °F per 1,000 ft) (3.0 °C/1,000 ft). The ...

  3. Air changes per hour - Wikipedia

    en.wikipedia.org/wiki/Air_changes_per_hour

    Air changes per hour, abbreviated ACPH or ACH, or air change rate is the number of times that the total air volume in a room or space is completely removed and replaced in an hour. If the air in the space is either uniform or perfectly mixed, air changes per hour is a measure of how many times the air within a defined space is replaced each hour.

  4. Air quality index - Wikipedia

    en.wikipedia.org/wiki/Air_quality_index

    An air quality index (AQI) is an indicator developed by government agencies [1] to communicate to the public how polluted the air currently is or how polluted it is forecast to become. [2] [3] As air pollution levels rise, so does the AQI, along with the associated public health risk. Children, the elderly and individuals with respiratory or ...

  5. Density of air - Wikipedia

    en.wikipedia.org/wiki/Density_of_air

    Air density, like air pressure, decreases with increasing altitude. It also changes with variations in atmospheric pressure, temperature and humidity. At 101.325 kPa (abs) and 20 °C (68 °F), air has a density of approximately 1.204 kg/m 3 (0.0752 lb/cu ft), according to the International Standard Atmosphere (ISA).

  6. National Ambient Air Quality Standards - Wikipedia

    en.wikipedia.org/wiki/National_Ambient_Air...

    Not to be exceeded more than once per year 40 CFR 50.5: Particulate matter (PM 10) Primary and Secondary 150 μg/m 3: 24-hour Not to be exceeded more than once per year on average over 3 years 40 CFR 50.6: Fine particulate matter (PM 2.5) Primary 9.0 μg/m 3 (12 μg/m 3 prior to May 6, 2024) [25] annual Annual mean, averaged over 3 years 40 CFR ...

  7. Cubic metre per second - Wikipedia

    en.wikipedia.org/wiki/Cubic_metre_per_second

    Cubic metre per second or cubic meter per second in American English (symbol m 3 ⋅ s −1 or m 3 /s) is the unit of volumetric flow rate in the International System of Units (SI). It corresponds to the exchange or movement of the volume of a cube with sides of one metre (39.37 in) in length (a cubic meter , originally a stere ) each second .

  8. Indoor air quality - Wikipedia

    en.wikipedia.org/wiki/Indoor_air_quality

    The value of 615 ppm above the outdoor concentration indicates approximately 15 cubic feet per minute of outdoor air per adult occupant doing sedentary office work where outdoor air contains over 400 ppm [123] (global average as of 2023). In classrooms, the requirements in the ASHRAE standard 62.1, Ventilation for Acceptable Indoor Air Quality ...

  9. Sustainable Development Goal 6 - Wikipedia

    en.wikipedia.org/wiki/Sustainable_Development_Goal_6

    In 2017 only 71 per cent of the global population used safely managed drinking water, and 2.2 billion persons were still without safely managed drinking water. Other water-related hazards related to flooding and drought also remain significant threats to human development and wellbeing.