In Semarang, during 2001-2004, the air quality showed a decreasing trend.28 If the
Pollutant Standard Index (PSI) reports are considered, the air quality in Surabaya shows some level of
improvement. This is evidenced by the increasing number of “Good Days” in the last 2-3 years.29 Similarly as
in Jakarta, beginning from 2005 to 2008, the number of “Good Days” tends to increase.