Trends in Air Pollutants in the Past 25 Years
Industries must report their air emissions to Environment Canada’s National Pollutant Release Inventory (NPRI).
Summaries of these data are published yearly to inform and to help people assess how effective regulations are.
Pre-Lab questions
1. Name five primary air pollutants
2. How many kilograms are equal to one tonne (1t)?
3. When is it appropriate to round off values to plan your graph?
Questions
How have emissions of certain air pollutants changed since 1985?
Procedures
1. Graph the data in Excel file table 1 and tab 2 to show the changes in SOx and CO emissions between 1985 and
2010 from 3 sources (industrial, non-industrial and mobile (transportation)).
2. Discuss how to graph the data. Use the Analyze and Interpret questions to know what type of analysis you are to
do, and use these questions:
 What variables will you plot on the x-axis and the y-axis? How will you label them?
 How many different line graphs do you need to draw?
 How can use different colours to help you compare the data?
3. Graph the data
4. Excel file tab 3 breaks down the individual non-industrial SOx sources of emissions. Decide how to graph the data
and then graph them.
Analyze and Interpret
1. Use these questions to summarize the trends in SOx and CO emissions.
 From 1985 to 2011, did emissions from industrial sources increase or decrease? What about emissions
from the non-industrial and transport sources?
 What overall percentage of increase or decrease in emissions for each pollutant form the time period?
o For each pollutant, divide the emission value form 2011 by the emission value for 1985, and
then multiply by 100.
o E.g. SOx emissions from industrial sources,

889 492
×
2 670 956
100 = 33.3024%
 Has there been a greater change in emissions levels for either of the air pollutants? How do you know?
 What other trends can you describe?
2. Summarize the trends in the graph for data for the non-industrial SOx sources of emissions.
Jackson , Ann, Ellen Murray , et al, et al. Environmental Science: A Canadian Perspective. 1. Whitby: McGraw-Hill Ryerson, 2013. Print.
Conclude and Communicate
3. Based on your knowledge of the sources of sulfur dioxide, what can you infer about the sources based on the
trends that the data show?
4. What do the non-industrial SOx sources of emissions indicate about the value of looking at contributions of
individual sectors? How can this improve guidelines for emissions and properly target the greatest contributors
of emissions?
5. Why must managing and reducing air pollution be a global undertaking? Hint: think about Canada and the
industries and populations that are close to our borders.
Jackson , Ann, Ellen Murray , et al, et al. Environmental Science: A Canadian Perspective. 1. Whitby: McGraw-Hill Ryerson, 2013. Print.