Over the past 30 years, researchers have unearthed a wide array of health effects which are believed to be associated with air pollution exposure. Among them are respiratory diseases (including asthma and changes in lung function), cardiovascular diseases, adverse pregnancy outcomes (such as preterm birth), and even death. In 2013 the World Health Organization concluded that outdoor air pollution is carcinogenic to humans.
A new study published in the latest issue of The Lancet Respiratory Medicine shows that pregnant women exposed to air pollution are at higher risk of having babies with low birth weight. The number of newborns born weighing less than two and a half kilos after a normal length of pregnancy increases when the content of fine particles in the air increases.
This effect could be seen even for levels far below the EU limits for the concentration of fine particles of 25 micro-grams per cubic meter of air.
The study was based on more than 74 000 births in Europe between 1994 and 2011.
The researchers measured concentrations of fine particulates and nitrogen oxides in the air and worked out the level of pollution on the streets where the women lived while pregnant. Air pollution had an overall bad effect on birth weight but fine particle matter was the single most contributing factor to low birth weight. Low birth weight increases the risk of death at birth, respiratory symptoms, reduced lung function and even cardiovascular disease and morbidity in adulthood.
For the individual child, the risk is much greater if the mother smokes. But for the whole population the number of babies born underweight due to smoking and due to air pollution is roughly the same.
Another study published in the American Journal of Respiratory and Critial care shows that children who lives in streets heavily affected by air pollution during their first year of life are at increased risk of reduced lung function as teenagers. These new findings come from the Swedish BAMSE study in which more than 2,000 children in the Stockholm area are followed to see how air pollution affects their lungs.
The level of nitrogen dioxide and particles in the air at the children’s home, preschool and school were measured. Lung function was measured with an FEV 1 test, where the amount of air you can blow out in one second determines how well the lungs function. The results show that children that had been exposed to more air pollution than the average for the group, were three to four times more likely to have an impaired lung function at age 16.
This research will be followed up to see if the effect of the polluted outside air remains in the group even in adulthood. It increases the risk that they suffer from allergies, asthma or lung disease coal even if it is small. The results of this study may be important in urban planning to avoid putting day-care centres and schools in heavily polluted areas.