Urban Atmospheric
Composition Processes
William Bloss
School of Geography, Earth and Environmental
Sciences, University of Birmingham,
Birmingham, UK
Article Outline
Glossary
Definition of the Subject
Introduction
Historical Perspective
Meteorology, Dynamics, and Mixing
Basic Composition and Key Pollutants
Key Emission Characteristics
Urban Atmospheric Composition Processes
Trends in Urban Atmospheric Composition
Future Directions
Bibliography
Glossary
Boundary layer The lowermost layer of the
atmosphere, in contact with the surface and
well mixed. Extending from 100 to 200 m at
night, up to 1–2 km during the day.
Mixing ratio The fraction of the air which a
given species comprises, typically parts per
million (10
6 ), billion (10
9 ) or trillion (10
12 ),
by volume.
NO x The sum of nitric oxide (NO) and nitrogen
dioxide (NO 2 ).
NO x limited The ozone production regime in
which VOCs are (relatively) plentiful, and ozone
production is limited by the availability of NO x .
Photostationary steady state The rapid chemical/
photochemical balance between a number of
reactants, usually applied to NO, NO 2 and O 3 .
PM 10 Suspended airborne particulate matter,
with an aerodynamic diameter of 10 mm or less.
Primary pollutants Those emitted directly to
the atmosphere, typically from mechanical or
combustion processes.
Secondary pollutants Those formed within the
atmosphere by chemical reactions.
Street canyon The semi-isolated atmospheric
compartment formed by adjacent rows of
multi-story buildings.
Temperature inversion An increase in temperature with increasing altitude, which usually
isolates ground-level air from the overlying
atmosphere, resulting in increased (primary)
pollutant concentrations.
Transboundary pollution The transport of
long-lived chemical species, such as O 3 and
CO, across national boundaries.
VOC Volatile Organic Compound, one commonly found overwhelmingly in the gas phase.
VOC limited The ozone production regime
where NO x is plentiful, and ozone production
is limited by the availability of hydrocarbons.
Definition of the Subject
The majority of the population now live in cities
(the 50% point was passed during 2007 [1]) and are
exposed to the urban atmosphere every day of their
lives. As global population has also doubled over
the past 50 years, urban air quality is a major factor
in pollutant exposure for billions of individuals.
The urban atmospheric environment is unique,
with the city landscape defining particular meteorological characteristics, and a wide range and high
density of emission (or pollution) sources, which
combine to determine local air quality. Air pollutants, ranging from gases such as carbon monoxide,
ozone and nitrogen dioxide, to suspended particles
of varying size and composition, have been shown
to be linked to respiratory and cardiovascular
health issues. Urban atmospheric composition processes affect the abundance of primary pollutants,
and are wholly responsible for the formation of
secondary species such as ozone. In this article,
© Springer Science+Business Media, LLC 2012
M. E. Goodsite et al. (eds.), Air Pollution Sources, Statistics and Health Effects,
https://doi.org/10.1007/978-1-0716-0596-7_493
Originally published in
R. A. Meyers (ed.), Encyclopedia of Sustainability Science and Technology, © Springer Science+Business Media LLC, 2012
https://doi.org/10.1007/978-1-4419-0851-3_493
215
Composition Processes
William Bloss
School of Geography, Earth and Environmental
Sciences, University of Birmingham,
Birmingham, UK
Article Outline
Glossary
Definition of the Subject
Introduction
Historical Perspective
Meteorology, Dynamics, and Mixing
Basic Composition and Key Pollutants
Key Emission Characteristics
Urban Atmospheric Composition Processes
Trends in Urban Atmospheric Composition
Future Directions
Bibliography
Glossary
Boundary layer The lowermost layer of the
atmosphere, in contact with the surface and
well mixed. Extending from 100 to 200 m at
night, up to 1–2 km during the day.
Mixing ratio The fraction of the air which a
given species comprises, typically parts per
million (10
6 ), billion (10
9 ) or trillion (10
12 ),
by volume.
NO x The sum of nitric oxide (NO) and nitrogen
dioxide (NO 2 ).
NO x limited The ozone production regime in
which VOCs are (relatively) plentiful, and ozone
production is limited by the availability of NO x .
Photostationary steady state The rapid chemical/
photochemical balance between a number of
reactants, usually applied to NO, NO 2 and O 3 .
PM 10 Suspended airborne particulate matter,
with an aerodynamic diameter of 10 mm or less.
Primary pollutants Those emitted directly to
the atmosphere, typically from mechanical or
combustion processes.
Secondary pollutants Those formed within the
atmosphere by chemical reactions.
Street canyon The semi-isolated atmospheric
compartment formed by adjacent rows of
multi-story buildings.
Temperature inversion An increase in temperature with increasing altitude, which usually
isolates ground-level air from the overlying
atmosphere, resulting in increased (primary)
pollutant concentrations.
Transboundary pollution The transport of
long-lived chemical species, such as O 3 and
CO, across national boundaries.
VOC Volatile Organic Compound, one commonly found overwhelmingly in the gas phase.
VOC limited The ozone production regime
where NO x is plentiful, and ozone production
is limited by the availability of hydrocarbons.
Definition of the Subject
The majority of the population now live in cities
(the 50% point was passed during 2007 [1]) and are
exposed to the urban atmosphere every day of their
lives. As global population has also doubled over
the past 50 years, urban air quality is a major factor
in pollutant exposure for billions of individuals.
The urban atmospheric environment is unique,
with the city landscape defining particular meteorological characteristics, and a wide range and high
density of emission (or pollution) sources, which
combine to determine local air quality. Air pollutants, ranging from gases such as carbon monoxide,
ozone and nitrogen dioxide, to suspended particles
of varying size and composition, have been shown
to be linked to respiratory and cardiovascular
health issues. Urban atmospheric composition processes affect the abundance of primary pollutants,
and are wholly responsible for the formation of
secondary species such as ozone. In this article,
© Springer Science+Business Media, LLC 2012
M. E. Goodsite et al. (eds.), Air Pollution Sources, Statistics and Health Effects,
https://doi.org/10.1007/978-1-0716-0596-7_493
Originally published in
R. A. Meyers (ed.), Encyclopedia of Sustainability Science and Technology, © Springer Science+Business Media LLC, 2012
https://doi.org/10.1007/978-1-4419-0851-3_493
215