Higher the pollution, higher the incidence of low birth weight, finds study
Pollution can affect babies even before they are born. A study has found that the babies of women who have been exposed to polluted air and smoke from vehicles and chimneys during pregnancy have low birth weight. This makes these babies prone to several health complications later in their life.
The researchers analysed data from a sample of more than three million births in nine nations in Europe, Africa and Asia to reach the conclusion. They say this study is the largest multi-centre study so far, reporting on the association between air pollution and foetal growth.
The research paper, published in Environmental Health Perspectives on February 6, concludes that higher the level of pollution in a region, more is the incidence of low weight births there. The researchers say low birth weight, defined as less than 2,500 grams, is associated with serious health consequences, including increased risk of pre-natal death, as well as ill-health and chronic health problems later in the life.
“As the air pollution increases, we can see that more babies are low weight at birth which in turn puts them at risk of poor health later in life,” says Tanja Pless-Mulloli of the Newcastle University, who led the UK study. “These microscopic particles, five times smaller than the width of a human hair, are part of the air we breathe every day. What we have shown definitively is that these levels are already having an effect on pregnant mothers.”
Call for tighter regulations
The researchers note that nations with tighter regulations on particulate air pollution have lower levels of these air pollutants. Particulate matter found in air pollution is measured in size (microns) and weight (micrograms per cubic metre or µg/m3). In the European Union, England and Wales the limit is 25 µg/m3 particles measuring less than 2.5 microns and regulatory agencies in Europe are currently debating whether to lower it.
In the US and Scotland, regulations require that there be no more than 12.0 µg/m3 particles measuring less than 2.5 microns annually. The researchers observed that particulate air pollution in Beijing in China recently measured over 700 µg/m3. “The particles which are affecting pregnant mothers mainly come from the burning of fossil fuels. In the past, the culprit may have been coal fires, now it is primarily vehicle fumes,” says Pless-Mulloli.
“This should not deter mothers-to-be from taking exercise outdoors as the benefits of keeping active in pregnancy are well known. This is not something that individuals can address, but policy makers who need to be considering,” says Judith Rankin, professor of maternal and pre-natal epidemiology at Newcastle University added.
Reacting to the study, Frank Kelly, professor of environmental health at King’s College in London says, “The study removes any doubt that poor air quality, in the form of particulate pollution, has detrimental effects on the unborn child. Increasing numbers of studies have suggested this to be the case but to date the evidence had been insufficient to infer a causal association. This study moves the field forward and clarifies the work now required to identify the nature and sources of the particulate pollution responsible to inform policies which remove these from the air.”