Over a million adolescents die globally every year due to preventable causes. This accounts for 3,000 young deaths each day, according to a latest report released by the World Health Organisation (WHO).

Road traffic injuries, lower respiratory infections and suicides  attributed to mental health  are the biggest causes of death among adolescents.  In 2015, more than two-thirds of these deaths occurred in low- and middle-income countries in Africa and South-East Asia, the report says, adding most of these deaths can be prevented with good health services, education and social support. But in many cases, adolescents who suffer from mental health disorders, substance use, or poor nutrition cannot obtain critical prevention and care services  either because the services do not exist, or because they do not know about them.

Also, many behaviours that impact health later in life, such as physical inactivity, poor diet, and risky sexual health behaviours, begin in adolescence.

Data in the report, Global accelerated action for the health of adolescents (AA-HA!): Guidance to support country implementation, suggests huge differences in causes of death when separating the adolescent group by age (younger adolescents aged 10Â14 years and older ones aged 15Â19 years) and by sex.

In 2015, road injuries were the leading cause of adolescent death among 10Â19-year-olds, resulting in approximately 115 000 adolescent deaths. Older adolescent boys aged 15Â19 years experienced the greatest burden. Most young people killed in road crashes are vulnerable road users such as pedestrians, cyclists and motorcyclists.

However, differences between regions are also stark. Looking only at low- and middle-income countries in Africa, communicable diseases such as HIV/AIDS, lower respiratory infections, meningitis, and diarrhoeal diseases are bigger causes of death among adolescents than road injuries, according to the report.

The picture for girls differs greatly. The leading cause of death for younger adolescent girls aged 10Â14 years are lower respiratory infections, such as pneumonia  often a result of indoor air pollution from cooking with dirty fuels. Pregnancy complications, such as haemorrhage, sepsis, obstructed labour, and complications from unsafe abortions, are the top cause of death among 15Â19-year-old girls, the report says.

“Adolescents have been entirely absent from national health plans for decades,” says Dr Flavia Bustreo, Assistant Director-General, WHO. “Relatively small investments focused on adolescents now will not only result in healthy and empowered adults who thrive and contribute positively to their communities, but it will also result in healthier future generations, yielding enourmous returns.”

Suicide and accidental death from self-harm, the report says, were the third cause of adolescent mortality in 2015, resulting in an estimated 67 000 deaths. Self-harm largely occurs among older adolescents, and globally it is the second leading cause of death for older adolescent girls. It is the leading or second cause of adolescent death in Europe and South-East Asia.

Adolescent health needs intensify in humanitarian and fragile settings, the report recommends. Young people often take on adult responsibilities, including caring for siblings or working, and may be compelled to drop out of school, marry early, or engage in transactional sex to meet their basic survival needs. As a result, they suffer malnutrition, unintentional injuries, pregnancies, diarrhoeal diseases, sexual violence, sexually-transmitted diseases, and mental health issues.