Woman holding a child who is wearing a face mask

Asthma in children linked to pollution exposure in the womb

Pregnant women exposed to high levels of tiny particles may give birth to children with a higher risk of asthma, according to a new study.

Pregnant women exposed to high levels of ultrafine particles in air pollution are more likely to give birth to children who later develop asthma. Findings from a new study by researchers at the Mount Sinai School of Medicine in the US are the first to link asthma to prenatal exposure to these tiny particles

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In the study, researchers followed 376 mothers and their children in Boston, tracking daily estimations of ultrafine particle levels (those less than 100 nm in diameter) in the areas around their homes. Many of the women involved lived near major roads with higher traffic density, where exposure to these particles tends to be higher.

When scientists followed up with the mothers, they found that a little over 18 per cent of their children developed asthma in their preschool years, compared to seven per cent of children overall in the United States.

Most instances of asthma began around the age of three and although boys and girls were affected, girls were found to be more sensitive when the exposure had occurred in late pregnancy. 

Ultrafine particulate pollution involves particles that are smaller than the width of a human hair. Researchers believe they can get deeper into our lungs and pass into our circulation to cause various health effects. In unborn children, pollution can also affect lung development and respiratory health, leading to conditions like asthma. 

More generally, air pollution has been linked with a grim spectrum of ill health, including hay fever, brain cancer, glaucoma and heart attacks.

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This study was focused on the US, where ultrafine particles are not monitored or regulated. In the UK, they are monitored to a degree and some environmental regulations – for instance those around diesel fuel and vehicle exhaust pipes – are believed to tackle them as an after-effect. However, other sources of ultrafine particles, including airports and shipping, are not regulated in the same way.

“One reason ultrafine particulates are not routinely monitored is that there have been a number of unique challenges to measuring them accurately,” said study author Professor Rosalind Wright. “Fortunately, recent methods have been developed to provide such exposure data which allowed us to conduct this study. 

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“As we advance methods for measuring these tiny particles, we hope for replication of these findings, both within different geographic areas across the United States as well as globally. Childhood asthma remains a global epidemic that is likely to grow with the anticipated rise in particulate air pollution exposures due to effects of climate change.”

Reader Q&A: Will electric cars reduce pollution?

Asked by: Kate Dennis, Durham

Electric vehicles’ engines don’t churn out polluting fumes, making them the obvious choice for improving local air quality in towns and cities.

But although they have the potential to drastically cut pollution, they are only as green as the electricity they run on. Given that most electricity globally is still produced by burning fossil fuels, charging an electric car can indirectly generate similar amounts of greenhouse gases to a petrol-powered vehicle, particularly in countries that rely heavily on coal power.

As the world embraces renewable energy, electric cars will increasingly gain the upper hand in years to come.