LTNs were introduced under emergency Covid legislation and Mr Emmerson said the changes were made “very quickly”.
They work by using CCTV cameras, bollards and giant plant pots to improve pedestrian and cyclist safety while blocking commuter traffic being diverted through residential areas.
Mr Emmerson told LBC radio: “Have they delayed responses? Yes, in certain situations I think they have delayed certain responses because they had to be put in very quickly.”
LTNs don’t show up on SatNavs so it hampers London Ambulance crews who are unfamiliar in the area, he said.
He added: “It is all right if you know the area, but our crews work all across London. Then, when going into an area of London they know less well and relying on satellite navigation that is not up to date – some new restriction has gone in – is where a lot of the problems occur.”
Earlier this year, it was revealed 159 separate incidents saw LTNs slow down ambulance crews in London over an eight-month period.
Hackney was named as the London borough with the highest proportion of streets covered by LTN schemes.
Recently, it emerged Londoners injured in road crashes have halved in LTNs.