Approximately 93% of the world’s children under the age of 15 — about 1.8 billion children — are breathing air that threatens their health and development, according to a new report released by the World Health Organization.

Between the lines: Children are more vulnerable to air pollution because they are still developing, but they also breathe more rapidly than adults and are therefore exposed to more pollutants, the authors write. Children are also physically closer to the ground, and therefore often take in pollutants at higher concentrations.

The big picture: Air pollution is responsible for almost 1 in 10 deaths in children under 5, making it a leading threat to child health.

Why it matters:

• Children exposed to air pollution can be at greater risk of cardiovascular disease and other chronic conditions later in life.
• Toxic air exposure can affect neurological development and cognitive ability. It can also trigger childhood cancer and asthma.
• Women who are pregnant and exposed to polluted air are more likely to give birth prematurely and have children at low birth weights.