Matt Bauer was also part of a group from Cardiff running the Boston Marathon yesterday.
Pictured on the right here, with his friend Stuart Trimby, he told us he feels very lucky at having crossed the line just one minute before the explosions happened.
At least three people were killed in the blasts, and more than 100 injured.
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It is going to stay fine and dry through the night with light winds.
It is going to stay fine and dry throughout.
There have been four deaths on the M4 in just the last eight days following crashes between Swansea and Newport.