Estimating Visibility and Air Quality Impacts
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Q4) The most widely used equation for estimating visibility is the Koschmeider equation:
Lv = 1200 km x µg/m3 / particle concentration
Where Lv is the visual range, the distance at which an average person can barely distinguish a dark object (such as a mountain or skyscraper) against the sky. This equation is an approximation, based on an average set of atmospheric particles.
- In the Grand Canyon and the surrounding area, on clear days, one can easily see mountains 120 miles away. What is the probable concentration of particles in the atmosphere when one can see that far?
- If the particle concentration in the atmosphere is increased by 1.5 µg/m3, what is the percentage decrease in the visual range if the initial range is 25 km? If the initial visual range is 200 km, what is the percentage decrease?
(a) Lv = 120 x 1.609 = 192 km
192 = 1200 / Particle Concentration
Particle Particle Concentration= 6.25 µg/m3
(b)25 = 1200/ particle conc
Particle Conc. = 48 µg/m3
So, particle conc. = 48 + 1.5 = 49.5 µg/m3
Lv = 1200 / 49.5 = 24.2 km
Decrease in visual range = 25 – 24.02 = 0.98 km
% Decrease in visual range = (0.98/25) x 100 = 3.92 %
(ii) Particle Conc. is increased by 1 µg/m3 at initial Lv = 200km
Determination of particle Conc. at Lv = 200 km
200 = 1200/ Particle Conc.
Particle Conc. = 6 µg/m3
Determination of Lv when particle conc. is increased by 1 µg/m3
So, particle conc. = 6 + 1 = 7 µg/m3
Lv = 1200 / 7 = 171.429 km
Decrease in visual range = 200 – 171.429 = 28.57km
% Decrease in visual range = (28.57/200) x 100 = 14.29 %
Q3) The USEPA lists chromium (VI) as a carcinogen with an inhalation route potency factor of 41 (kg/mg×d)-1. A sludge incinerator with no air pollution control equipment is expected to emit chromium (VI) at a rate such that the airborne concentration at the plant boundary immediately downwind of the incinerator is 0.005 µg/m3. Will it be necessary to treat emissions so as to reduce the chromium to stay within the risk level of 1 cancer per 106 people?In addition , write the present status of carcinogen gas in KSA. How will those gases be reduced? Wasit Gas Plant is one of the largest gas plants we have ever built. Adding Wasit to our portfolio represents a significant increase in our gas processing capacity and reflects our commitment to increasing supplies of cleaner-burning natural gas, reduce emissions and support new industries.
According to US EPA, a standard receptor weighs 70 kg, breathes 20 m3 of air per day, and lives for 70 yr. Assuming linear dose-response, allowable daily intake can be calculated from:
Risk = chronic daily intake (CDI) x potency factor
2 x 10 -6 = CDI x 41 (mg/kg-d)-1
CDI= 0.0487 x 10 -6 mg/kg-d
The allowable concentration:
CDI = volume of air inhaled per day x concentration of chromium (VI)/kg body weight
0.0487 x 10 -6 mg/kg-d= 
C = 0.17x 10-3 mg/m3,
0.005 mg/m3>0.17x 10-3mg/m3 emission control is necessary.
Q1) how do you handle three pollutants CO,HC and NOx emission from automobile? Write different alternative fuels to control toxic emission from motor vehicles ? what is photo-chemical smog ? how does it generates in the air ?
The three pollutants emission from automobiles can be reduced greatly by using a catalytic convertor. Automobile emission occur when there is an incomplete combustion in the engine .the use of hybrid cars as well as electric cars can greatly reduce toxic emission .
Photo chemical smog is a haze in the atmosphere produced when sunlight reacts with pollutants. Photo chemical smog contains O3 and NOx which can be harmful to our environment as well as to human health.Q2) What are PHEV , EV and FCV ? Describe briefly? In addition , write the present status in KSA .
A PHEV, on the other hand, is an HEV with enough extra battery capacity
FCV is the ideal future vehicle would be one that converts hydrogen and oxygen in a fuel cell to produce electricity.
EV is The drive power system of EV is consists of motor/generator, battery bank.