Children living in high stress households are more vulnerable to lung damage from traffic pollution than children whose parents are less stressed out, according to the results of a new study.
"It makes sense," said Dr Jane Clougherty from the University of Pittsburgh, who was not involved in this study. "The bodily wear and tear induced by stress could make the individual more susceptible to the effects of traffic-related air pollution."
The researchers took assessed lung function in nearly 1,400 children living in southern California.
They also predicted the amount of traffic pollutants the children were exposed to by sampling almost 1,000 different sites around the area. In particular, they were looking for nitrogen oxides, which are formed when fuel is burned. Nitrogen oxides can damage lung tissue and make asthma worse, according to their online paper in the American Journal of Respiratory and Critical Care Medicine.
Increase in nitrogen oxides causes decline in lung function
Six years earlier, the children's parents had filled out a questionnaire about their level of stress. The questions asked how often they felt able to handle personal problems or felt in control, for instance.
Air pollution levels varied widely, depending on where the children lived, from six parts per billion of nitrogen oxides to 101 parts per billion.
For kids from high stress homes, for every increase of 22 ppb of nitrogen oxides, their lung function declined by 4.5%.
That same increase in pollutants around a child whose parents had a low level of stress made no difference to their lung function, however.
Decrease in lung function not tested on children’s health
Dr Talat Islam from the University of Southern California, the lead author of the study, said he expected that stress would lead to a bigger effect of pollution on kids, but he was surprised that increased air pollution had no effect on the kids from low stress homes.
"We see the whole effect of traffic-related air pollution in those children who were exposed to higher stress," Dr Islam told Reuters Health.
Dr Islam's group did not test whether that decrease in lung function had any effect on the children's health or comfort.
An earlier study by some of the same researchers found that children exposed to traffic-related air pollution and a high stress home were 51% more likely to develop asthma than children exposed to the same pollutants, but in a low stress environment.
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It's not clear what might underlie the links between pollution, a stressful household, and lung function, but Dr Islam said that stress and pollutants are both tied to inflammation and tissue damage.
Dr Clougherty said it's important for parents to consider – if they have a choice – their children's exposure to traffic and air pollution when deciding where they should live, play and go to school.
But as the results indicate, she added, "the social environment might be equally, if not more, important to the child's health overall."
(Reuters Health, July 2011)