I think it is Sulfur Dioxide (SO2) and Nitrogen Oxides (NOX).
This are some of the things behind imperialism in Africa.
1) Need for resources,
2) Political competition
3) Technological advances
Economic factors were more of a driving force behind imperialism because the imperialists were in need for natural resources for them to improve their technology and their national pride.
-cantidad de muertes anuales (causas naturales)
-cantidad de muertes anuales (causas no naturales)
-cantidad de inmigrantes anuales
-cantidad de emigrantes anuales
by size, shape and composition?