By Dr Sandeep Chadha
According to the World Health Organization, air pollution is responsible for more than 4 million deaths annually. 91 percent of the global population lives in an area or country where the pollution levels are greater than the safe standards set by the WHO. Although plenty of studies have drawn links between inhalation of air pollutants and conditions such as asthma and other respiratory diseases, researchers have also begun to uncover a link between air pollution and in utero development of fetuses.
Researchers have found that there is a correlation between breathing polluted air and the gestation periods, birth weights, and lung health after birth. Even more troubling is the fact that children as young as 5 were found to be suffering from respiratory problems, which is a serious problem because it means that the condition is going to track them for the rest of their lives. Some studies have also shown that repeated exposure to polluted air while the child is in the womb might also cause behavioral problems and sleep disorders later in life. The medical community is yet to fully embrace the idea as correlational studies are not enough to prove the fact that there is a direct causal relationship between air pollution and fetal development.
How exactly does air pollution harm unborn children?
Because correlational studies cannot sufficiently explain the mechanism by which developing fetuses are affected by the pollution their mothers are exposed to, researchers have turned to animal experiments over the last few years to gain more insight into the subject.
In an experiment conducted at Texas A&M University, researchers exposed pregnant rats to ultrafine ammonium sulphate, which was associated with greater chances of premature births, low birth weights, and stillbirths. In human studies, researchers have had trouble delineating the effects specific compounds, even though ammonium sulphate is a part of the mixture. However, some scientists believe that the chemical makeup of the compound might not be as important as its size. The smaller ones can get deeper into the system compared to the big ones. Ultrafine particles, that are less than 0.1 micrometer in diameter, can move through the cell membrane and even found in the cells lining the lungs. The smallest of them can wade through the system and make their way to the placenta. These pollutants have been shown to react with the proteins and lipids in the cell membrane, causing inflammatory responses. It is speculated that these responses might signal pathways that induce labor.
Another study found that air pollution affects more than just the metabolism of unborn kids. Scientists at the University of California found signs of neuroinflammation as well. If there is inflammation of the fetus' brain, there is a good chance that it may end up affecting their neurodevelopment after birth, although we will need more studies to substantiate this theory. Whatever the case may be, these preliminary animal and epidemiological studies have shown that the adverse effects of air pollution go well beyond preterm birth and birth weight and may affect individuals for the rest of their lives. Predicting people who are at risk will be an area of focus for researchers in the field.
(The columnist is Consultant, Obstetrics & Gynecology, Motherhood Hospital, Noida. Views expressed are the author's own.)