How to Publish Information Safely

Removing personal data from information requests and datasets

Overview

There are several ways personal data can be stored in a file and disclosed by mistake.

However, exporting data to simple file formats such as CSV (Comma Separated Value) and using the inspect worksheet function can highlight potential unauthorised disclosures.

Mistakes can be made in the redaction process and other file types such as email or images can contain additional meta-data.

Hidden data – Hiding in plain sight

The simplest case of data
being disclosed in error can occur when it is not
immediately visible on
screen but elsewhere within
the file. This can be due
to design choices or
formatting styles.
Within a template, a user
might have chosen to hide
certain data by setting the
font colour to the same as
the background (eg white on
white or black on black).
While this prevents personal
data being disclosed on a
printed version of the file
it will still remain within the
source file.
The personal data is at risk
of unintended disclosure if
the electronic version is
distributed. Highlighting the
text or changing the font
colour will expose it.

This data is at risk if
the electronic version is
distributed. Highlighting
the text or changing the
font colour will expose it.

Redaction

When disclosing information under FOI or in response to a subject access request, it may be necessary to redact certain information. In particular you should consider whether the information requested contains personal data. The ICO’s advisory note – which places a moratorium on the disclosure of original source spreadsheets to online platforms – includes a number of useful reminders and links on the safe disclosure of information.

Checklist

What you need to consider when disclosing information – a summary of the ICO guidance, for further information please see the What is personal information guidance.

Spreadsheet eg xls(x), ods

• Convert the file to CSV
• Use Document Inspector in Excel
• Are you sure you know where all the data is?
• Are there hidden columns or rows?
• Are there hidden work sheets?
• Do pivot tables contain linked data?
• Do charts contain linked data?
• Are there formulas which link to external files?
• Is there meta-data that should be removed?
• Is the file size larger than you might expect for the volume of data being disclosed?

Word processor eg doc (x), odt

• Are there comments within the document that should be removed? Eg Section 40(2) exemptions
• Does the document contain a version history?
• Do pivot tables contain linked data?
• Do charts contain linked data?
• Is there meta-data that should be removed?
• Does the document title or filename contain personal data (eg Letter to John Smith)?
• Has a header or footer been automatically added to a printout?

Presentation eg ppt(x), odp

• Are there presenter notes that should be removed? Eg Section 40(2) exemptions
• Do pivot tables contain linked data?
• Do charts contain linked data?
• Is there meta-data that should be removed?

PDF

• Are there comments that should be removed?
• Are all redactions effectively applied?
• Is there meta-data that should be removed?

Email eg mbox, msg

• Is there data within any attachments that also needs to be redacted?
• Is there meta-data that should be removed?

Image and video eg jpg, avi

• Is there attached EXIF data?
• Is there personal data that needs to be obscured (eg faces of third-party individuals)?

For in-depth guidance, read the ICO’s How To Disclose Information Safely

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