"PDFs can be bad for accessibility. It can be difficult for users to customise them for ease of reading, and often they do not work very well with assistive technologies like screen readers.
Wherever possible, create content in HTML formats. If you cannot avoid publishing a PDF, it should be in addition to an HTML version.
As a minimum, any PDF you publish must meet Level AA of the Web Content Accessibility Guidelines (WCAG) 2.0."