The document contains various problems related to air pollution meteorology, focusing on atmospheric stability conditions, wind speed estimations at different altitudes, maximum mixing depth calculations, minimum stack height determinations, plume rise estimations, and emission rate calculations from coal-fired power plants. Each section presents specific scenarios with data sets, requiring the application of relevant formulas and models for environmental impact assessments. This resource is intended for civil engineering students specializing in air pollution control.

1. Prof S S Jahagirdar, NKOCET
AIR POLLUTION
AND CONTROL
(Elective-I)
Problems set for
UNIT-IV
AIR POLLUTION METEOROLOGY
Page | 1

2. BE (Civil)
L-
ROLL NO-
Air pollution (Elective -I)
Unit-IV
Stability conditions (Temperature gradient) Problems
1.
On the basis of temperature gradient in the situation described below classify the degree of
stability of atmosphere.
i.
ii.
Temp at ground 350C and temp at 650 m height is 220 C
iii.
Temp at ground 250C and temp at 700 m height is 280 C
iv.
2.
Temp at ground 340C and temp at 500 m height is 400 C
Temp at ground 250C and temp at 200 m height is 50 C
Temperature at ground level is 30OC. Find the atmospheric stability condition in each
of the following cases.
Case
Temp. (OC)
I
700
10
II
500
34
III
1000
25
IV
3.
Altitude (m)
500
20
Determine whether the atmosphere is unstable, neutral or stable for the following case.
Initial Temperature
30.2 oC
Final Temperature
- 58.5 oC
Initial Height
221 m
Final Height
23214 m

3. BE (Civil)
L-
ROLL NO-
Air pollution (Elective -I)
Unit-IV
Finding Wind speed at higher altitudes Problems
1.
The wind speed at 10 m altitude is 5m/s. Find the wind speed at 250 m altitude for
the following stability conditions.
i.
ii.
Zero or small lapse rate
iii.
Moderate inversion
iv.
2.
Large lapse rate
Large inversion
Wind speed at 10 m altitude is 2m/s. Find the wind speed at 200 m altitude for
following cases
i.
ii.
Zero lapse rate
iii.
Moderate inversion
iv.
3.
Large lapse rate
Large inversion
The ground level wind velocity at 10 m elevation is 5.2 m/sec in a city. What would
you estimate the velocity to be at 125m elevation in moderately stable atmosphere?

4. BE (Civil)
L-
ROLL NO-
Air pollution (Elective -I)
Unit-IV
Maximum Mixing Depth (MMD) Problems
1.
At a given location the ground Environmental air temperature is 180 C, while normal
maximum surface temperature for the month is known to be 300 C. At an elevation of
700 m the temperature of the atmosphere measured is a) 150 C and b) 200 C. What is
maximum mixing depth in meters for two cases?
2.
Air parcel temp at ground level is 280C. The environmental temperature at ground
level is 300 and at 500 m is 27.5 0C. Determine the MMD
3.
A rising parcel of dry air has a temp of 300 C at sea level. Assuming DALR of 10C/100m, determine MMD if environmental temperature temp at sea level is 150C
and ELR is +10C/100 m
4.
In a given situation ground level temperature is 180C, while normal maximum surface
temp for that month is a) 26 0C and b) 240C. At an elevation of 300 m the temperature
is found to be 210C. What is MMD in metres for both the cases?
5.
A rising parcel of dry air has a temp of 350 C at sea level. Assuming DALR of 10C/100m, determine MMD if environmental temperature temp at sea level is 150C
and ELR is +10C/100 m
6.
Determine the maximum mixing depth if flue gas temperature is 30oC, when:
i)
Average ground temperature is 20 oC and temperature at elevation of 600 m
is 30oC
ii)
Average ground temperature is 25 oC and temperature at elevation of 500 m
is 20oC
Assume DALR= -9.8 oC/1000 m.
7.
Calculate the maximum mixing height from the following early morning temperature
data given below:
Height (m)
0
250 350 450 550 650
Temperature (oC) 9.5 12.2 15.1 15.6 16.2 16.5
The maximum surface
temperature for the day was
15oC.

5. BE (Civil)
L-
ROLL NO-
Air pollution (Elective -I)
Unit-IV
Minimum (safe) Stack height determination Problems
1.
A factory uses 1.5 ML of fuel oil per month. The exhaust gases from factory
contain the following quantities of pollutant per ML per year:
i.
Particulate matter = 5 t/yr
ii.
Sulphur dioxide= 21 t/yr
Determine the safe height of chimney required for safe dispersion of pollutants.
2.
A factory uses 2 ML of fuel oil per month. The exhaust gases from factory contain
the following quantities of pollutant per ML per year:
i.
Particulate matter = 5 t/yr
ii.
Sulphur dioxide= 21 t/yr
iii.
Nitrogen dioxide= 4 t/yr
Determine the safe height of chimney required for safe dispersion of pollutants.

6. BE (Civil)
L-
ROLL NO-
Air pollution (Elective -I)
Unit-IV
Plume rise Problems
1.
The heat emission rate associated with a stack gas is 4800 KJ/sec, the wind and
stack gas speeds are 5 m/s and 15 m/s respectively and the inside dia of stack top is
2m. Estimate the plume rise by
i.
ii.
Concave
iii.
2.
Carson Mosses
Holland’s formula
The wind and stack gas speeds are 3 m/s and 6 m/s respectively and stack dia is 2m.
The atmospheric stability condition is neutral with a temp of 3000K and the stack gas
temp is 4400K. Estimate plume rise in m by Brigg’s equation and TVA model
equation.
3.
Determine the effective stack height given by following data
i.
ii.
Inner dia of stack = 1.07 m
iii.
Air temp =130C
iv.
Barometric pressure = 1000 mbar
v.
Stack gas velocity = 9.14 m/s
vi.
Stack gas temperature = 1490 C
vii.
4.
Physical stack height= 203 m
Wind velocity at stack top = 5 m/s
Determine the effective stack height given by following data
i.
Physical stack height= 180 m
ii.
Inner dia of stack = 0.95 m
iii.
Air temp =20 0C
iv.
Barometric pressure = 1000 mbar
v.
Stack gas velocity =11.12 m/s
vi.
Stack gas temperature = 1600 C
vii.
Wind velocity at stack top = 2.75 m/s

7. BE (Civil)
L-
ROLL NO-
Air pollution (Elective -I)
Unit-IV
Emission rate Problems
1.
A power plant burns coal at the rate of 500 kg/hr. It consists of ash 30 %, Sulphur -3
% and carbon 40 %. Determine the emission rates of SPM and SO2 in mg/m3 and
gm/sec.
2.
A power plant burns coal at 500 kg/hr per MWe. Capacity of power plant is 500
MWe.
Coal contains 30 % ash and 1 % sulphur and 40 % carbon.
Determine
i)
ii)
SO2 and CO2 emission
iii)
3.
SPM emission
Quantity of air required for combustion.
A power plant burns coal at the rate of 500 kg/min. It consists of ash 30 %, Sulphur 1 % and carbon 40 %. Determine the emission rates of SPM, CO2 and SO2 in mg/m3
and gm/sec.
4.
A power plant burns 25 tonnes of coal/day having 30% ash. Determine the efficiency
of particulate matter control equipment to maintain SPM level below 150
microgram/m3. If stack dia is 2.5 m and flue gas velocity is 9 m/s.
5.
A power plant uses 500 kg of coal/hr. Coal contains 40% ash and 2% sulphur. Stack
diameter at exit is 2 m and the stack gas velocity is 20 m/s and temp is 1000C.
Calculate
i.
SPM concentration in microgram/m3
ii.
SO2 emission in ppm
iii.
How much efficiency should be kept for the dust control equipment to
meet emission standard of 150 micrograms/m3

8. BE (Civil)
L-
ROLL NO-
Air pollution (Elective -I)
Unit-IV
Gaussian dispersion model Problems
1.
A thermal power plant burns coal at the rate of 10 t/hr and discharges the fuel gas
though a stack having effective height of 90 m. The coal has sulphur content of 4%.
The wind speed at stack top is 6m/s. The atmospheric stability class is ‘C’. For this
class at downwind distance of 2000m the constants σy and σz are 200 and 120
respectively. Find the concentration of sulphur dioxide at ground level at 2000m
downwind and 500m crosswind distance.
2.
A power plant burns 5 tons of coal per hour with 4% sulphur content, discharges the
product through a stack with 75 m effective height. The velocity of wind at top of
stack is 6 m/s and atmospheric stability class is ‘C’. Determine the maximum ground
level concentration of SO2. Also determine the ground level concentrations at 3.0 km
downwind and cross wind distance of 0.4 m on the either sides of centreline for ‘C’
class stability on the either side of centreline
Distance in m
σz in m
850
88
53
3000
3.
σy in m
280
170
A coal fired power plant emits SO2 at a rate of 200 g/s. If effective stack height is 60
m determine the ground level concentration downwind if wind speed at 60 m height
is 4 m/s and stability class prevailing is ‘B’
Distance
0.5 km
1 km
2 km
3 km
σy in m
70
160
310
420
σz in m
50
140
360
700
Plot concentration versus distance on log x log scale.
4.
A coal fired power plant burns 20,000 tonnes of coal per day. Coal contains 3%
sulphur, physical stack height=150 m, stack dia at top 4m, Stack gas velocity= 20
m/s and temperature is 1400 C. Surrounding air temperature is 1200 C and pressure
1000 mbar. Wind speed at 150 m = 6 m/s, Env lapse rate = +10 C/100 m.
Determine
1. Plume rise by Brigg’s formula
2. SO2 concentration at 1000 m downwind from stack (centreline) for ‘B’

9. BE (Civil)
L-
ROLL NO-
class stability, if σy in m= 170 and σz in m= 140 at 1000 m.
5.
A coal fired power plant emits SO2 at a rate of 100 g/s. If effective stack height is
100 m determine the ground level concentration downwind if wind speed at 100 m
height is 4 m/s and stability class prevailing is ‘B’
Distance
0.5 km
1 km
2 km
3 km
σy in m
70
160
310
420
σz in m
50
140
360
700
Plot concentration versus distance on log x log scale.
6.
A coal fired power plant emits SO2 at a rate of 300 g/s. If effective stack height is
150 m determine the ground level concentration downwind if wind speed at 10 m
height is 4 m/s and stability class prevailing is ‘B’
Distance
1 km
2 km
3 km
σy in m
70
160
310
420
σz in m
7.
0.5 km
50
140
360
700
SO2 is emitted at a rate of 0.9 kg/sec from a stack with effective height of 220 m.
The wind speed at that height is 5 m/sec and stability category is ‘B’. Determine the
downwind centre line concentration in micrograms/m3 at ground level distance from
stack of 1) 0.5 km 2) 1km,3) 2km and 4) 3km. Plot C versus log of distance curve
Distance
1 km
2 km
3 km
σy in m
110
160
300
450
σz in m
8.
0.5 km
65
120
220
310
A coal fired power plant burns coal at the rate of 500 kg/hr. Coal contains 1%
sulphur and
30% ash, physical stack height=100 with plume rise of 50 m. Wind
speed at stack top is 5 m/sec.
Determine
1. Determine SO2 and SPM emission rate.
2. Also determine GLC of SO2 and SPM at 1000m from stack for ‘B’ class
stability, if σy in m= 60 and σz in m= 25 at 1000 m.
Assume all the other data.
9.
An industrial boiler is burning at 12 tons (10.9 mton) of 2.5% sulfur coal/hr with an
emission rate of 151 g/s. The following conditions exist: H = 120 m, u = 2 m/s, y =
0. It is one hour before sunrise, and the sky is clear. Determine downwind ground
level concentration at 10 km.

10. BE (Civil)
10.
L-
ROLL NO-
If emissions are from a ground level source with H = 0, u = 4 m/s, Q = 100 g/s, and
the stability class = B, what is downwind concentration at 200 m?
11.
A stack in an urban area is emitting 80 g/s of NO. It has an effective stack height of
100 m. The wind speed is 4 m/s at 10 m. It is a clear summer day with the sun
nearly overhead.
Estimate the ground level concentration at:a) 2 km downwind on the centerline and
b) 2 km downwind, 0.1 km off the centerline.