Pollution Control And Treatment Of Effluents

Step 1: Understanding the Distributions
- The lognormal distribution is commonly used to model environmental pollutant concentrations because these concentrations tend to be positively skewed, meaning they have a long tail to the right. This is typical for pollutants such as particulates in the air or contaminants in water.
The Poisson distribution is used to model rare events or occurrences over time, such as the exceedance of pollutant concentrations above a certain threshold. This distribution is appropriate for modeling the frequency of exceedances over a given period.
Step 2: Analyzing the Statements
Statement (i) is correct because environmental pollutant concentrations are indeed typically modeled using the lognormal distribution.
Statement (ii) is incorrect because the Poisson distribution is not typically used to model pollutant concentrations themselves, but it is used for rare events like exceedances.
Statement (iii) is incorrect because the weekly rate of exceedance is not modeled by the lognormal distribution, but rather by the Poisson distribution.
Statement (iv) is correct because the Poisson distribution is appropriate for modeling the rate of exceedance of pollutant concentrations.
Thus, the correct answers are (A) and (B).

Step 1: Analyze Statement P.
According to the National Ambient Air Quality Standards (NAAQS), notified by the Central Pollution Control Board (CPCB) in 2009:
Annual average standard for
Annual average standard for
Step 2: Analyze Statement Q.
The National Air Quality Index (AQI) released in 2015 uses sub-indices for pollutants including and .
Sub-index values are calculated based on concentration ranges. It is possible for levels to fall in a lower AQI category (e.g., 'Moderate'), while levels fall in a higher one (e.g., 'Poor'), based on their respective concentration thresholds. Final Conclusion:
Both statements P and Q are TRUE.