BS ISO 4225:2020 pdf free.Air quality — General aspects—Vocabulary.
This document specifies terms and definitions that are related to air quality (see 3.1.1.1). These areeither general terms or are used in connection with the sampling (see 3.3.3.1) and measurement ofgases, vapours (see 3.1.5.8)and airborne particles (see 3.2.2.1) for the determination of air quality.
The terms included are those that have been identified as being fundamental because their definition isnecessary to avoid ambiguity and ensure consistency of use.An alphabetical index of the terms is provided in Annex A.
This document is applicable to all International Standards,IS0 Technical Reports，ISO TechnicalSpecifications, and ISO Guides related to air quality.
There are no normative references in this document.For the purposes of this document, the following terms and definitions apply.
air quality:features of the air which have an impact on humans(e.g., safety and health) and/or the environment
Note 1 to entry: Air quality is typically expressed in terms of the presence or absence of air pollution (3.2.1.2)(e.g.emissions(3.2.1.4) or conversions resulting from emissions,e.g.,ozone),using one or more measurements.
Note 2 to entry: The concept of air quality can be used in reference to ambient air(3.1.1.3), indoor air(3.1.1.5), orworkplace air (3.1.1.7).
air quality standard:specified attribute of the air intended to prevent or minimize impacts on humans(e.g. safety and health)and/or the environment
Note 1 to entry:Air quality standards are frequently defined statistically by setting a limit to the concentrationof an air pollutant (3.2.1.1) over a specified averaging time (3.1.1.9).
Note 2 to entry: Air quality standards can have legal or advisory status in one or more jurisdictions.
nanoparticle:material with all three dimensions in the size range from approximately 1 nm to 100 nm3.1.3.5
nanostructured particle particle with structural features smaller than 100 nm, which can influence its physical, chemical and/orbiological properties
Note 1 to entry: A nanostructured particle can have a maximum dimension substantially larger than 100 nm.EXAMPLE A 500 nm diameter agglomerate (3.1.3.6) of nanoparticles (3.1.3.4) would be considered ananostructured particle.
agglomerate <aerosols> group of particles held together by relatively weak forces, including van der Waals force,electrostatic forces and surface tension.BS ISO 4225 pdf download.