Visibility and Particulates in Air

1
Visibility and Particulates in Air
Depends on nature and concn of
particulates   Gas phase rxns ---gt particles
---gt effects visibility   Eg Haze in Los
Angeles, Denver. Smog in Baton
Rouge.   Without any particulates in air,
visibility should generally be of the order of
150 miles!!.   If no atmospheric circulation is
possible, particulates remain suspended in
air.   Smaller particulates have lower settling
velocities.  
Limit of Visibility (Lv)      
Coefficient of Haze (Coh) - ASTM Std D 1704-16
2
Visibility Limit
I I0 exp (-?d)
d
I
Io
Note ? a (for absorption) s (scattering)
For aerosols, ? s N K ?r2
Visibility minimum for average person occurs
whenI 2 of Io.
i.e., 0.02 exp (-?Lv). Thus Lv 3.9/?
Now, C ? (4/3) ?r3 N, and hence,
Lv (5.2 ? r)/(KC)
3
Coh/ 1000 ft Degree of air pollution   0 to
0.9 light   1 to 1.9 moderate 2 to
2.9 heavy   3 to 3.9 very heavy   4 to
4.9 extremely heavy
4
Deposition of aerosols in the respiratory tract
(mouth breathing)
5
Deposition of aerosols in respiratory tract (nose
breathing)
6
(No Transcript)
7
(No Transcript)
8

9
Effects of CO on Humans
10
(No Transcript)
11
Health Effects of Organic Vapors

• Volatile Organic Compounds (VOC's) are an
  important health and environmental concern for
  several reasons
• Some VOC's can be hazardous to your health when
  inhaled. For example, benzene is a probable human
  carcinogen and toxic. Likewise, formaldehyde is
  both an irritant and a sensitizer. Many VOC's are
  flammable.
• VOC's from outgassing of fabrics, building
  materials etc. are an important contributor to
  sick building syndrome (SBS).
• VOC's such as hydrocarbon (gasoline, petroleum
  distillates) emissions from cars and trees are
  important contributors to photochemical smog.
• Some VOC's such as methyl tert-butyl ether (MTBE,
  once added to gasoline to make it burn more
  cleanly) have a fair solubility and rather high
  mobility in groundwater, leading to the
  contamination of drinking water wells.

12
(No Transcript)
13
(No Transcript)
14
(No Transcript)
15
(No Transcript)
16
(No Transcript)
17
(No Transcript)
18
(No Transcript)