Nitrogen dioxide NO2 is produced by fuel burning, particularly in diesel vehicles.
Air pollution is as bad for pregnant women as smoking in raising the risk of miscarriage, according to a scientific study. They said the finding was upsetting and that toxic air must be cut to protect the health of the next generation.
Air pollution is already known to harm foetuses by increasing the risk of premature birth and low birth weight. Recent research has also found pollution particles in placentas.
The effect of long-term exposure to dirty air on the risk of miscarriage has been analysed previously. Studies from Brazil to Italy to Mongolia found a link, but others failed to do so.
However, the latest study is the first to assess the impact of short-term exposure to air pollution. It found that raised levels of nitrogen dioxide (NO2) pollution that are commonplace around the world increased the risk of losing a pregnancy by 16%.
Dr Sarah Stock, at the University of Edinburgh and not part of the research team, said: “Air pollution is clearly detrimental to the health of millions of mothers, babies and children worldwide. Measures to reduce the impact of air pollution are crucial to ensure the health of future generations.”