The Portal Database, in constant updating, provides the latest data on the various statistical operations of this theme but also allows access to the historical series.

In the indicator table presented after the selection of the theme, the possibility is given to use the existing arrows to sort the columns according to the desired result. Thus, in the column “Reference period” — “Initial” can be used the “order asc/desc” arrow to obtain the most backward information (start date of the indicator).

As a result of this sorting, the table begins with the oldest indicators, as is the case with a set of indicators started in 1971, which have as their source the Portuguese Institute of the Sea and the Atmosphere, followed by other sources of Statistics Portugal that have made indicators available since 1989, such as statistics on the expenditure of central and regional administration on environmental protection.

It should be noted that the table containing the information of the selected indicator shows by default the most recent information. Therefore, to obtain previous years, click on the menu option “Change selection conditions”, from which you can access the dimensions of the selected indicator to change the dimension “Data reference period”, and choose the available years desired.