If you have to use a JPEG, then I was under the impression that 676px was the widest image size we would be allowed. (I sent a JPEG of this size). If possible, use the larger JPEG that I also sent, "CAB Infographic 19 - 2817px across.jpg"
But it would be MUCH better if you could use an SVG. Here is the JPEG, and below I will put the SVG.
CAB Infographic 19 - only 676px across.jpg
Examples of some CAB projects:
This is the SVG version (it's vector based, so it has no resolution. It should never be blurry.
CAB Infographic 19 - only 676px across.jpg
Kate Baldwin