On 07 July 2005, four bombs were detonated in London, killing 52 members of the public. Approximately 700 individuals received treatment either at the scene or at nearby hospitals.

Significant concerns about the potential long-term psychological and physical health effects of exposure to the explosions were raised immediately after the bombings. To address these concerns, a public health register was established for the purpose of following-up with individuals exposed to the explosions.

Invitations to enroll in the register were sent to individuals exposed to the explosions. A range of health, emergency, and humanitarian service records relating to the response to the explosions were used to identify eligible individuals. Follow-up was undertaken through self-administered questionnaires. The number of patients exposed to fumes, smoke, dust, and who experienced blood splashes, individuals who reported injuries, and the type and duration of health symptoms were calculated. Odds ratios of health symptoms by exposure for greater or less than 30 minutes were calculated.

A total of 784 eligible individuals were identified, of whom, 258 (33%) agreed to participate in the register, and 173 (22%) returned completed questionnaires between 8 to 23 months after the explosions. The majority of individuals reported exposure to fumes, smoke, or dust, while more than two-fifths also reported exposure to blood. In addition to cuts and puncture wounds, the most frequent injury was ear damage. Most individuals experienced health symptoms for less than four weeks, with the exception of hearing problems, which lasted longer. Four-fifths of individuals felt that they had suffered emotional distress and half of them were receiving counseling.

The results indicated that the main long-term health effects, apart from those associated with traumatic amputations, were hearing loss and psychological disorders. While these findings provide a degree of reassurance of the absence of long-term effects, the low response rate limits the extent to which this can be extrapolated to all those exposed to the bombings. Given the importance of immediate assessment of the range and type of exposure and injury in incidents such as the London bombings, and the difficulties in contacting individuals after the immediate response phase, there is need to develop better systems for identifying and enrolling exposed individuals into post-incident health monitoring.