Air Pollution Particles in the air
Air Pollution- Particles in the Air
Air quality and particles · Epidemiological(流行病学) evidence associates atmospheric particles with diseases and mortality Particles penetrate the lungs, blocking and irritating air passages. Particles themselves could exert toxic effects. (toxic substances present in the particles) [polycyclic Aromatic Hydrocarbons are examples of toxic substances in aerosols
Air quality and particles • Epidemiological (流行病学) evidence associates atmospheric particles with diseases and mortality. – Particles penetrate the lungs, blocking and irritating air passages. – Particles themselves could exert toxic effects. (toxic substances present in the particles) [Polycyclic Aromatic Hydrocarbons are examples of toxic substances in aerosols.]
Gullet or esophagus Larynx Windpipe or trachea Body wal 尽 Pleura covering Pleural cavi Space occupied Left lung Cut op Anatomy of the human respiratory system
The larger a particle is, the 090 more likely it is 0.80 deposited into z9-0z2 NASAL-P the upper part of the respiratory 0.60-额 Pulmonary system 0.50 F040 The smaller a Oau particle is, the 03 deeper it can get · BRONCHIAL into the respiratory ystem 051. 501oo MASS MEDIAN DIAMETER (um) Particle deposition as a function of particle diameters in various regions of the lung
Particle deposition as a function of particle diameters in various regions of the lung. The larger a particle is, the more likely it is deposited into the upper part of the respiratory system. The smaller a particle is, the deeper it can get into the respiratory system
Terms TSP: Total suspended particulate matter RSP: Respirable suspended particulate matter PM10: Particulate matter of less than 10 um equivalent to RSP. PM25: Particulate matter of less than 25 um
Terms • TSP: Total suspended particulate matter • RSP: Respirable suspended particulate matter • PM10: Particulate matter of less than 10 um; equivalent to RSP. • PM2.5: Particulate matter of less than 2.5 um
Air quality standards for particles US 15 ug/m3(annual average)for PM 2. 5 um 65 ug/m3(daily average)for PM 2. 5 um Hong Kong RSP: 55 ug/m3(annual),180 ug/m3(daily) TSP: 80 ug/m3(annuaL),260 ug/m3(daily)
Air quality standards for particles • US – 15 ug/m3 (annual average) for PM 2.5 um – 65 ug/m3 (daily average) for PM 2.5 um • Hong Kong – RSP: 55 ug/m3 (annual), 180 ug/m3 (daily) – TSP: 80 ug/m3 (annual), 260 ug/m3 (daily)
Visibility and aerosols Visibility is generally better in summer夏学的视野通常比 Creat Hong Hong Contrat on Photograpy Fourvdlaston曹考沿 In a clear sky without any particles, one can see as far as100-300km the same vew in winter冬季的国一景象
Visibility and Aerosols In a clear sky without any particles, one can see as far as 100-300 km
Physics of visibility visibility depends on the transmission of light through the atmosphere and the ability of the eye to distinguish an object because it contrasts with the background A change in contrast with viewing distance occurs for both dark, light and bright objects With dark objects, the atmosphere introduces light, called"air light", to the sight path, and the dark object appears lighter at increasing distance until it bleeds into the background at the horizon With light objects, light is lost from the sight path with increasing viewing distance
Physics of visibility • Visibility depends on the transmission of light through the atmosphere and the ability of the eye to distinguish an object because it contrasts with the background. • A change in contrast with viewing distance occurs for both dark, light and bright objects. – With dark objects, the atmosphere introduces light, called "air light", to the sight path, and the dark object appears lighter at increasing distance until it bleeds into the background at the horizon. – With light objects, light is lost from the sight path with increasing viewing distance
In both cases the result is the same- The contrast between the object and the background approaches zero when the light coming along the line of sight from the object approaches the intensity of the light from the background at the horizon When the eye can no longer distinguish the difference, the contrast, between the object and the background the object can not be seen, and it is said to be beyond the limit of visibility
In both cases, the result is the same— The contrast between the object and the background approaches zero when the light coming along the line of sight from the object approaches the intensity of the light from the background at the horizon. When the eye can no longer distinguish the difference, the contrast, between the object and the background, the object can not be seen, and it is said to be beyond the limit of visibility
diagram of extinction of light from a source such as an electric light in a reflector, illustrating(i)transmitted, (ii) scattered, and(ii)absorbed light. (b)A diagram of daylight visibility, illustrating (1) residual light from a target reaching an observer, (i)light trom a target scattered out of an observers line of sight, (ii) air light from the intervening atmosphere, and (iv) air light constituting horizon sky