There will a period of silence held before the start of the London Marathon and runners are also being encouraged to wear black ribbons after the Boston marathon blasts.
Virgin London Marathon, the organisers, have pledged to donate £2 for every finisher in the race to The One Fund Boston set up to raise money for victims of the explosions.
Roughly 35,500 people are expected to cross the finish line on The Mall, meaning at least £70,000 is likely to be raised.
Tatyana McFadden, who won the women's wheelchair race in the Boston Marathon on Monday, has confirmed she will still take part in the London Marathon and is 'running for Boston':
More top news
A Freedom of Information request revealed the cost of burying Raymond Morris which included a £15 floral tribute.
The international community is failing refugees from Iraq and Syria who have been displaced by Islamic State insurgents, says UN ambassador.
There will be a three-way split across the UK this afternoon, weather-wise.