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Published in:
2021 | OriginalPaper | Chapter
Air Quality, Surface Transportation Impacts on
Author : Paul Boulter
Published in: Air Pollution Sources, Statistics and Health Effects
Publisher: Springer US
Excerpt
DPF
Diesel particulate filter, the preferred and most effective technology for removing particulate matter from diesel exhaust. DPFs can be broadly divided into two types: “full flow” and “partial flow.” The latter are more permeable and are less effective, but need no maintenance. DPFs physically capture particles and can fill up rapidly. They must therefore be periodically “regenerated,” and several passive and active systems have been developed for this purpose.
Emission standard
A value that specifies the maximum amount of a pollutant that can be released into the environment per unit activity (e.g., g/km or g/kWh).
NO 2
Nitrogen dioxide, a gaseous air pollutant produced as a result of combustion. NO
2 is also a precursor for a number of harmful secondary air pollutants such as ozone, and plays a role in the formation of acid rain. Long-term exposure to high concentrations of NO
2 causes adverse health effects, and levels regularly exceed air quality standards.
O 3
Ground-level ozone, a secondary pollutant produced by reactions between NO
2, hydrocarbons, and sunlight. High levels of ozone are generally observed during hot, sunny weather, and concentrations tend to be higher in rural areas than in urban areas.
PM 10
Mass concentration of particles with an aerodynamic diameter of less than 10 μm. Particles smaller than 10 μm (also known as “thoracic” particles) can settle in the bronchi and lungs.
PM 2.5
Mass concentration of particles with an aerodynamic diameter of less than 2.5 μm, sometimes referred to as “fine” or “respirable” particles. Particles in this size range can penetrate deep into the lungs.
Primary particles
Particles emitted directly to the atmosphere, typically as a result of combustion or abrasion processes.
SCR
Selective catalytic reduction, an exhaust aftertreatment method that is used to reduce emissions of nitrogen oxides. It will be the main technology for enabling compliance with future emission standards.
Secondary particles
Particles formed within the atmosphere from gas-phase precursors. These include particles originating from atmospheric oxidation of sulfur and nitrogen oxides, and their reaction products with ammonia, and from the oxidation of organic compounds.
Ultrafine particles
Particles with a diameter of less than 0.1 μm. These can pass through cell membranes and migrate from the lungs into other organs. There is evidence to indicate that they may be more damaging to the cardiovascular system than PM
10 and PM
2.5.