List of top Air and Noise Pollution Questions

The equipment that can be used to control particulate air pollution in an industrial unit is/are
Which is/are the secondary air pollutant(s)?
A gravity settling chamber of height ‘H' and length ‘L' is designed to control particulate air pollution. In the chamber, the horizontal velocity of air flow is $'V_h'$ and terminal settling velocity of the target particle is $'V_ť$. Which one of the following expressions is the correct concept used to calculate the minimum size of the target particle that will be removed with 100% efficiency?
In a cyclone separator of radius 25 cm, a particle is travelling with a gas stream at velocity of 18 m/s. The ratio of centrifugal force to the gravitational force acting on the particle is ________(rounded off to 2 decimal places).
Consider acceleration due to gravity (g) as 9.8 m/s2.
Two sources of noise, adjacent to each other in a room, have sound pressure levels of 30 and 40 decibel (dB). The combined sound pressure level in the room is _________ dB(rounded off to 2 decimal places).
Use reference sound pressure as $20 \mu Pa$.
An industrial stack emits 100 g/s of CO at an effective height of 'H', where the wind speed is 5 m/s. At 3 km distance downwind, the values of dispersion coefficient in y- direction and z-direction are 50 m and 25 m, respectively. The CO concentration at the centerline of the plume at 3 km distance downwind is ________ \(mg/m^3\) (rounded off to 2 decimal places)?  Use Gaussian plume model and value of \(\pi\) = 3.14. Neglect reactions and the ground effect of plume in the calculations.