Police have asked schools across London to warn pupils about illegal raves after the deaths of two teenagers with links to Croydon.
Commander Simon Letchford, of the Metropolitan Police, has written to headteachers to help "prevent a further tragedy" by talking to youngsters and their parents about unlicensed events.
It follows the deaths of Addiscombe 16-year-old Daniel Spargo-Mabbs, who died after taking drugs at a party in Hayes in January, and Rio Andrew, 15, who collapsed at the rave in East Croydon earlier this month.
In the letter, sent to secondary schools, sixth-form colleges and pupil referral units, Commander Letchford said: "As we approach the summer holiday period, some students may be considering their options to relieve exam pressure and may be attracted by the lure of an event such as a rave.
"It is important that those of us with responsibility for safeguarding young people do all in our power to prevent a further tragedy. The Metropolitan Police Service seeks your assistance with this by asking you to address your students, and their parents, on the dangers of attending such events."
He asks schools to highlight dangers of unlicensed events, such as overcrowding, easier access to drugs, and the absence of health and safety regulations.
Approximately 2,000 people, many of them teenagers, attended the rave in the former Royal Mail sorting office in Cherry Orchard Road on June 14.
The cause of neither teenager's death has yet been established.