Overview
ISO 4226:2007 is an international standard published by the International Organization for Standardization (ISO) that specifies the units of measurement for air quality reporting. This third edition replaces earlier versions and provides standardized units to ensure consistency and comparability of air quality measurement results worldwide. The standard is essential for professionals involved in environmental monitoring, air pollution assessment, and related scientific research.
By establishing a harmonized set of units, ISO 4226:2007 supports accurate communication and data exchange across borders and disciplines, enabling reliable comparison of air quality data between countries and agencies.
Key Topics
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Standardized Units for Air Quality Data
ISO 4226:2007 specifies precise units for reporting various air quality parameters including gas concentrations, particle measurements, and meteorological data.
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Units for Gases and Vapours
- Volume or mass fraction: Percent (%)
- Volume fraction of gaseous pollutants: Cubic centimetre per cubic metre (cm³/m³), cubic millimetre per cubic metre (mm³/m³)
- Molar fractions: Millimole per mole (mmol/mol), micromole per mole (µmol/mol), nanomole per mole (nmol/mol)
- Mass concentration: Milligram per cubic metre (mg/m³), microgram per cubic metre (µg/m³), nanogram per cubic metre (ng/m³), picogram per cubic metre (pg/m³)
- Diffusion coefficients: Centimetre squared per second (cm²/s), centimetre squared per minute (cm²/min)
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Units for Particulate Matter
- Mass concentration: mg/m³, µg/m³, ng/m³, pg/m³
- Particle size: Micrometre (µm), nanometre (nm)
- Atmospheric dustfall: Gram per square metre per day (g/(m²·d)), milligram per square metre per day (mg/(m²·d))
- Deposition rate and velocity: µg/(m²·s), cm/s
- Number concentration of biological or other particles: Reciprocal cubic metre (m⁻³), reciprocal cubic decimetre (dm⁻³)
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Specifications for Gas State
- Temperature: Kelvin (K), degree Celsius (°C)
- Pressure: Pascal (Pa), kilopascal (kPa)
- Relative humidity: Percent (%)
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Meteorological Parameters
- Wind speed: Metre per second (m/s)
- Wind direction: Degrees (°)
- Precipitation intensity: Millimetre per day (mm/d), millimetre per hour (mm/h)
- Irradiance: Watt per square metre (W/m²)
- Atmospheric pressure: Hectopascal (hPa), kilopascal (kPa)
- Absolute humidity and mixing ratio: Gram per cubic metre (g/m³), gram per kilogram (g/kg)
- Visibility: Kilometre (km)
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Time and Location Units
- Time: Second (s), minute (min), hour (h), day (d)
- Geographic coordinates: Degree (°), minute ('), second (")
- Universal Transverse Mercator (UTM) coordinates: Metre (m)
- Altitude: Metre (m)
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Guidance Notes
- Usage of abbreviations such as ppm or ppb is discouraged.
- Concentrations expressed on a mass/volume basis require specification of ambient temperature, pressure, and humidity.
- Wind direction is reported as degrees clockwise from true north.
Applications
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Environmental Monitoring Agencies
ISO 4226:2007 enables standardized reporting of air pollutants, ensuring data quality for regulatory compliance and public health studies.
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Scientific Research
Researchers use the standard units for consistency in air quality experiments, facilitating reliable comparison and replication of results.
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Industrial Emission Monitoring
Industries monitoring emissions can adopt ISO 4226 to report pollutant concentrations in legally accepted units.
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Air Quality Modeling and Forecasting
Uniform units improve the integration and validation of air quality models supporting policy making and urban planning.
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International Data Exchange
Facilitates harmonization and comparison of air quality information in cross-border environmental studies and agreements.
Related Standards
- ISO 1000 - Provides general guidance on the International System of Units (SI), complementing ISO 4226 by specifying unit multiples and recommendations.
- ISO 31-0 - Establishes general principles for quantities and units, important for understanding the foundation of ISO 4226’s unit system.
- ISO/TC 146 Subcommittee SC 4 - The technical committee responsible for air quality standards development including measurement methods and reporting.
Adhering to ISO 4226:2007 ensures clarity, consistency, and precision in air quality measurement reporting, supporting effective environmental management and scientific research worldwide. For more information and access to the full document, visit ISO official website.
