Traffic pollution linked to low birth weight of unborn babies, study reveals

A new study published yesterday by The BMJ warns that air pollution caused by road traffic in London has a harmful impact on babies’ health while still in the womb.

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According to the study carried out by Imperial College London researchers, exposure to road traffic air pollution in London during pregnancy is linked to an increased risk of low-birth weight babies born at full term. Traffic-related noise pollution showed to have no effect.

Indicating that the results are applicable to other cities across UK and Europe, the team called for environmental health policies to bring about better air quality in urban areas.

Previous studies had shown a connection between childhood illness, pregnancy complications, and air pollution, but studies on the impact of noise pollution on pregnancy produced inconsistent results.

The current research investigated the association between exposure to both noise and air pollution in road traffic during pregnancy with two birth weight outcomes-low birth weight, i.e., less than 2,500 g and being born small for the gestational age.

The team used national registers to examine more than 540,000 live, single, full time births between 2006 and 2012 within Greater London.

They recorded the mother’s home address at the time of birth and the average levels of traffic pollutants (such as nitrogen oxides (NOx), nitrogen dioxide (NO2), and fine particulate matter (PM2.5) from traffic exhaust and non-exhaust sources, including brakes or tire wear) and larger particulate matter (PM10) were estimated Noise levels during the day and night-time traffic were also estimated.

After analyzing the data using statistical models, the researchers found that increases in traffic-related air pollutants-particularly PM2.5--were linked with 2%–6% increased odds of low birth weight and 1%–3% increased odds of being small for gestational age, even after road traffic noise was accounted for.

Although there was no proof for the independent association of increased exposure to road traffic noise with birth weight, the authors stated they cannot rule out the chance of an association in a study area with a wider range of noise exposures.

The authors stated that the air pollution from road traffic can significantly affect fetal growth. They also found that the average annual concentration of PM2.5 in 2013 was 15.3 g m3, and also estimated that reducing the PM2.5 concentration by 10% would approximately prevent 3% (90) of babies being born at full-term with low birth weight in London each year.

With the annual number of births projected to continue increasing in London, the absolute health burden will increase at the population level, unless air quality in London improves,"

Researchers at the University of Edinburgh argued that the onus is on policy makers to protect women and unborn babies. They added that even though the findings from the UK are of concern, "a global perspective reveals something approaching a public health catastrophe."

They used Beijing as an example of what coordinated action can achieve, referring to the improvement of air quality during the 2008 Olympics. The challenge, they said, lies in maintaining reductions in the longer term via combinations of national and local authority action, especially in reducing congestion and implementing interventions to overcome diesel combustion emissions in urban areas.

The study is expected to promote awareness that prenatal exposure to small particle air pollution is harmful to unborn infants. However, the researchers stressed that increasing awareness without providing solutions to the issue risks feeding maternal anxiety and guilt.

The researchers concluded that to overcome the issue of traffic related air pollution, and reduce health risks for the next generation, immediate, broad, multi-sector action is needed.