William Checkley of the Hopkins Center for Global Health has been studying situations in which pollutants exacerbate the symptoms of children’s asthma.
In his latest study, Checkley found that the closer children live to highways, the more likely they are to develop asthma. Children all across the world suffer from asthma to varying degrees, but all too often, poor environmental conditions aggravate their condition.
For several years, Checkley and his team have collected and analyzed data from an impoverished shantytown population near Lima, Peru. The area is geographically ideal to his most recent project, which has been to elucidate the effects of traffic pollution on adolescent asthma.
The shantytown is located close to the main avenue that runs through Lima, and although there are other minor roads crossing the city, none produce nearly as much traffic as the single highway.
“We chose this place because there is basically no traffic other than this main avenue,” Checkley said. “There are no industrial sources of pollution nearby, so this gave us a unique place for studying traffic-induced asthma. Obviously this was a single source of traffic-related pollution.”
Because of his team’s long-standing relationship with the community, they were able to expedite several preliminary processes.
“We keep a study of about 40 to 60 thousand people,” said Checkley. “We maintain and update a census, so it is easy for us to obtain samples.”
For this particular project, Checkley and his colleagues chose a random sample of 700 adolescents from the shantytown. They used questionnaires and clinical allergy skin tests before and after treatment with asthma-alleviating bronchodilators.
They were looking for a response to the medication, specifically reversibility of the asthmatic symptoms and improvement in lung function after giving the participants the inhaled medication. In addition, Checkley used GPS tracking to calculate perpendicular and actual distances of the children’s homes from the main avenue.
Checkley and his team found that the instances of asthma and allergic reactions rose as distance from the main road decreased. Allergic reactions, or atopy, was an important measure of the adolescents’ health.
“Allergic disease is a well-known factor for asthmatic disease,” explained Checkley. “Basically, they [the participants] have an increase in blood serum IgE and this increases the inflammatory response. In any population where you see an increase in atopy, you will see an increase in asthma.”
Other factors can also affect one’s chances at contracting asthma, including weight and smoking habits. Checkley accounted for such factors using interviews and questionnaires.
“Obesity is related to asthma — a higher body mass index means a higher likelihood,” said Checkley. “Smoking is related to asthma in several ways and is one huge risk factor from both personal and secondhand smoke.”
Not only does smoking increase one’s chances of suffering from asthma, but the addictive habit can also decrease the effectiveness of inhaled corticosteroids, such as those that Checkley’s team administered to the participants.
Checkley ensured the honesty of the adolescents by asking them about their smoking habits only when their parents were absent. “We have to have parental consent for everything, but they were more comfortable when the parents were not around,” said Checkley.
While the shantytown in Lima provides an ideal place for studying a single source of traffic pollution, Checkley has replicated his results in other parts of Peru.
“Shantytowns are 60 percent of Lima — our data is representative of Lima as a whole, but there are some areas of higher density,” Checkley said.
However, he hopes that traffic can be regulated such that children’s asthma can be reduced. “Politicans need to be made aware of these things,” he said. “There is a lot of unregulated traffic and a specific situation where there is no public transportation system per se.”
Checkley believes that the problem with public transportation provides the Peruvian government with an opportunity for intervention. “Reduce or curb the unregulated traffic, organize it a little bit better and think more carefully about public transportation needs, especially for large cities like Lima, which has 10 million people,” he suggested.
He mentioned some places that have made progress in controlling traffic, such as Santiago, Chile and Mexico, where it is actually illegal to circulate cars for one day each week.
In terms of the study itself, Checkley wants to determine the source of pollution and the exact pollutants that are making the children sick.
For example, Checkley is looking at NO2 and diesel-related particles. He plans to study how these emissions have negative effects on oxidative stress. He is also interested in gene-environment interaction since the researchers discovered that not everyone close to the avenue has asthma.
“Epigenetics has become a new interest,” said Checkley. “We are looking at how methylation of genes can mold your phenotype and trying to see if there’s any change in methylation as you get closer to the road.”
While genomics would provide a wealth of information about asthma, the relatively short-term response to this research is clearly to regulate traffic and reduce emissions so that the Peruvian kids can finally breathe easily.
