Chapter 21, Problem 100A

Interpretation Introduction

Interpretation:

The average PAH concentrations should be compared before 1905 and after 1925.

Concept introduction:

PAH is a short form of polycyclic aromatic hydrocarbons that contain two or more fused aromatic rings. They are naturally occurring compounds and human activities can result in increase in the concentration of PAH in the environment.

Explanation of Solution

Given:

From the given figure, the average PAH concentration before 1905 is quite low that is from $\text{0-4 μg/g}$ and after 1925 is from $\text{11-15 μg/g}$. The large increase in concentration is observed from 1905 to 1925 due to increase in burning of fossil fuels and at early 1940’s the effects of pollution on environment were being understood so, the companies and government started making control over some pollutions and thus, after 1925 the level was somehow controlled but still higher than the concentration before 1905.