The trauma of the 7 July London bombings have left emotional scars for 80% of survivors, a report says.
Fifty-two people died in the bombings
The Health Protection Agency said 80% of this group received counselling, and others were referred to specialist post traumatic stress disorder services.
Many of those close to the explosions also report hearing problems.
However, the survey of 158 people caught up in the bombings found no other significant long-term health impact from the attacks.
The attacks by four suicide bombers on three Tube trains and a bus killed 52 people and injured hundreds.
In total 59% of the people who responded to the detailed questionnaire were injured in the blasts.
One third of this group reported ongoing problems with their hearing.
Ongoing problems with breathing and headaches were reported by 2% of both the injured and uninjured.
The HPA report also says that the risk to the public from exposure to airbourne particles generated by the explosions was very low.
The only material released by the blasts to which people may have been exposed was identified as tunnel dust.
Professor Pat Troop, HPA chief executive, said long-term follow up of the health impact of the London bombings provided vital information that could be used to help protect people involved in any future incidents in the UK.
"These results provide reassurance that there are no other long-term health effects," she said.
"The agency will continue to monitor, and provide feedback to all those who took part in the follow-up."