penetrate our respiratory system and cause possible health
problems. Researchers have been using PM10 to study air
pollution since it can be used as an indicator to explain how
good or bad the air quality is. Figure 1 shows PM10 levels in
each region around the world. The world average PM 10 is 70
micrograms per cubic meter, which is higher than the EPA's
annual air quality standard guideline of 50 micrograms per
cubic meter. The figure also illustrates that developing
countries are facing more significant air pollution problems
than more developed countries.
Figure 1. PM10 levels by region, for the last available year in the period 2008-2012.
Note. The data are adapted from “WHO’s Ambient Air pollution Database-Update
2014,” by World Health Organization website. Retrieved from