Evidence for Increasing Nitrogen and Sulfur Oxides


There is no current evidence for a global increase in the concentrations of sulfur and nitrogen oxides, however there is direct and indirect evidence that they have been increasing in localised areas.

Direct Evidence

Strengthening Evidence:

  • Quantitative analysis of Antarctic ice core drilling by the CSIRO has indicated that there has been steady increase in the concentrations of these oxides in the past few decades.
  • Although the average of these oxides haven't been increasing in cities has not increased significantly, the number of days where concentrations have exceeded safety levels has been increasing.

Weakening Evidence:

  • The equipment used to measure the oxides of nitrogen and sulfur are slightly unreliable. Levels of these oxides usually stay around 0.01 ppm and it becomes difficult to measure their concentrations with a high degree of confidence.
  • In addition to this there has been no data before the 1950s to indicate that industrialised pollution has been a major factor of producing oxides of nitrogen and sulfur.
  • It wasn't until the 1970s that the development of infra-red spectroscopy allowed for fine tuned detection could be made.
  • Oxides of sulfur and nitrogen can also exist in aqueous form in the atmosphere and eventually wash out into rivers and lakes where it does the most damage. There are no known ways to reliably produce accurate measurements of these aqueous concentrations.

Indirect Evidence:

Strengthening Evidence:

  • There has been increasing incidence of acid rain in localised areas where sulfur and nitrogen pollution is high.
  • There has been direct evidence of increasing incidence of heavy metal contamination, an effect of decreasing pH in water ways which leech heavy metal contaminates from rocks.

Weakening Evidence:

  • The evidence is inherently flawed as it is indirect, other variable that we may have not taken into account could have affected the results.

Conclusive Assessment

Although we do not have evidence to suggest a global increase in the concentration of these oxides, a combination of these evidences is enough to suggest that there are localised concentrations of oxides of sulfur and nitrogen and that they have been increasing since the industrial revolution.

IMPORTANT The conclusive statement above affirms enough evidence to suggest an increase I strongly recommend you do not use the converse. You may however include that the evidence may be insufficient to tell either way but since there is strong evidence to suggest local impacts it is still a major concern.