Airborne pollutants can cause permanent biochemical and immunological changes in respiratory tissues, and the systems of the young are particularly vulnerable to damage which may be long-lasting.
Evidence is emerging that children living near roads with heavy vehicle traffic have about a 50% higher risk of suffering from respiratory symptoms than children living in areas with low traffic.
In 1997, one in seven children in the UK suffered from asthma, which is exacerbated by air pollution: 13 times as many were admitted to hospital with the disease each year as in 1960.
Asthma afflicts as many as one in seven European schoolchildren. Children are more vulnerable than adults because they have proportionately narrower airways, which are more easily obstructed, and their oxygen demand is higher (a nine-year old has to breathe in 25% more air, relative to body weight, to get the same amount of oxygen as an adult). Children in Czech and Slovak industrial areas have twice the average rate of respiratory infections.
Air pollution particles have been found on the foetal side of placentas, indicating that unborn babies are directly exposed to the black carbon produced by motor traffic and fuel burning. The research, led by Prof Tim Nawrot at Hasselt University in Belgium, is the first study to show the placental barrier can be penetrated by particles breathed in by the mother. The link between exposure to dirty air and increased miscarriages, premature births and low birth weights is well established. This research suggests the particles themselves may be the cause, not solely the inflammatory response the pollution produces in mothers. The team also found black carbon particles in the urine of primary school children. The study, published in 2017, found an average of 10 million particles per millilitre in hundreds of nine-to-12-year-olds tested. This shows there is translocation of particles from the lungs to all organ systems.