Air pollution from traffic can have detrimental effects on your baby's health. In particular, pregnant women who breathe dirty air may have babies with low birth weight, according to a new study published in The BMJ on Tuesday. And air pollution is also nullifying the benefits of exercise, another study, published on Tuesday in The Lancet, showed.
In the previous study, researchers investigated the relationship between air pollution caused by transit during pregnancy and birth with low birth weight and / or small for gestational age (how late the baby was born) . They collected data from the national birth registry in the London metropolitan area of 540,000 births between 2006 and 2010, and compared them with the average amounts of air pollutants including nitrogen dioxide, nitrogen oxides and fine particles (called PM2.5) of the escape of traffic or other sources of traffic. The noise levels of day and night traffic were also estimated.
Air pollutants, especially particulates, were associated with an increase of 2 to 6 percent in low birth weight and an increase of 1 to 3 percent in the probability of being small for gestational age. Particulate matter, which comes from power plants, automobiles, construction sites, chimneys and fires that cause chemical reactions in the air, is carcinogenic, according to the World Health Organization (WHO). These particles can travel deep into the lungs because of their small size, 30 times smaller than the thickness of human hair.
The measurement of exposure to air and acoustic contamination is difficult, what the authors pointed out was a limitation of the study. Even so, the researchers, led by Rachel Smith, epidemiologist of statistics at the public health school of Imperial College London, concluded that their findings "suggest that the pollution of London's traffic is adversely affecting fetal growth." Considering that the number of babies born each day, it is projected that the year in London will continue to rise, wrote the authors of the study, "the absolute health burden will increase at the population level, unless the air quality improves in London".
Reducing air pollution in London by particles by 10 percent could prevent 90 babies, or 3 percent-fro "Being born with low birth weight in London," according to the study. (Acoustic contamination was also taken into account, but no relationship was found with birth size or weight.)
More than 20 million children worldwide are born each year with low birth weight, according to WHO . This characteristic of the newborn has consequences specifically during childhood and childhood. Low birth weight is more often due to premature birth, small size for gestational age or both. Babies who weigh less than 5.5 pounds at birth, most of whom are born in developing countries, are at greater risk of slow growth problems, developmental delays, infectious diseases, and death during childhood and childhood.
The second study, also conducted in London, revealed that air pollution could cancel the exercise of benefits, especially in older adults. Adults over 60 years who exercised had lower benefits when walking on a busy street in London compared to those who walked in a park. 
Using data from a much more complex As small as the low birthweight study, the researchers recruited 119 volunteers from a hospital in London who were over 60 years old. Some were healthy and others had stable chronic obstructive pulmonary disease (COPD) or stable heart disease. The participants walked for two hours in London at noon, once in a quiet park and again in a bustling section of Oxford Street, a main street. Specific air pollutants were not measured or estimated.
The walk through the park had apparent benefits: lung capacity improved in one hour and lasted more than 24 hours in some cases. Blood flow increased, while blood pressure decreased. Arteries became less rigid in more than 24 percent in healthy volunteers with COPD, and more than 19 percent in those with heart disease.
But the benefits of walking on arterial stiffness were reduced by walking down Oxford Street. The maximum improvement in artery stiffness was 4.6 percent for healthy volunteers, 16 percent for those with COPD, and 8.6 percent for those with heart disease. 
"Our research suggests that we could advise older adults to walk in green spaces, away from urbanized areas and traffic pollution," the lead author and professor of respiratory medicine at Imperial College London, Fan Chung, said in a statement. . Stress, noise and activity could have affected the results of the study, the authors said.
"It is possible that studies like this can support new air quality limits," Chung said in a statement. He added that "it shows that we really can not tolerate the levels of air pollution that we currently find in our busy streets."
The two new studies add to a growing body of evidence on health problems related to air pollution. In November, another study found that particulate matter in air pollution was associated with smaller and differently shaped sperm, which the authors noted could lead to widespread infertility. Another report found that 24,000 lives of improved air quality from other countries in the US could be saved. UU In 2050.
Air pollution was attributed to 3 million premature deaths worldwide in 2012, 90% of which -countries, according to the WHO. But everywhere in the world, air pollution remains a concern. In 2014, 92 percent of the world's population lived in places where the WHO air quality guidelines were not met.