Lan Jin (F&ES)
Lan Jin (F&ES) received a CEAS Summer Travel & Research Grant to support 2 months of research in China. The title of her project was, “Proximity to Heavy Traffic and Congenital Heart Defects in Lanzhou.”
To see photos from her research trip, click here.
To begin, could you please provide a brief summary of your research?
My research focuses on the health impacts of air pollution, especially for susceptible populations in less developed countries and areas. In my current project, I am investigating the relationship between maternal exposures to air pollution and congenital heart defects (CHD) in Lanzhou, China. I am also interested in the interaction between air pollution and social factors, including social economic status and lifestyle choices, and how these factors modified the impacts of air pollution on human health.
How did you first get interested in your topic of research?
Air pollution is the ninth risk factor of global disease burden. Globally, ambient particulate matter pollution accounted for 3.1 million deaths and 3.1% of disability-adjusted life years from 1990-2010. However, some countries and areas disproportionately experience high levels of air pollution and this disparity is increasing over time. Air pollution has been linked to numerous health outcomes, including cardiovascular, respiratory disease, and adverse birth outcomes. As extreme air pollution events have increased in China in recent years, Chinese people, as well as foreign talents living in China, are concerned about their and their children’s health. CHD is the most prevalent type of birth defects globally, and its prevalence is highest in Asia, where no studies have been done to investigate the impacts of air pollution on CHD. In addition, both air pollution exposures and health outcomes are influenced by many social factors, such as education, income, urbanicity, and occupation. Therefore, it is important to identify, quantify, and control for these factors in order to study the health impacts of air pollution.
What did you do for your summer project?
I focused on one pollution source—traffic pollution—this summer, after I found air pollution exposures estimated using monitoring data were significantly associated with increased risk of CHD risk in a birth cohort in Lanzhou, China. This birth cohort was directed by Professor Yawei Zhang at the Yale School of Public Health. There are two parts in my summer project. The first part is to construct a horizontal profile measurement of traffic pollution to depict the dispersion pattern of pollution from roads. I conducted measurements at different distances to a major road for seven days continuously. Three pollutants were measured: black carbon (BC), nitrogen dioxide (NO2), and particles with diameter no more than 10µm (PM10).
The second part of my project is to link traffic pollution to CHD. In this pilot study, I randomly selected 40 births (20 cases and 20 controls) who were born from 2010-2012 in the largest hospital in Lanzhou, China. I visited their residence at birth (outside the buildings) twice to conduct measurements of the above three pollutants. Then, I did a statistical analysis to see whether or not there was an association between traffic pollution levels at their residence and the CHD risk. Because the small sample size in the pilot study, I could not control for the social factors of the mothers that have been collected in our previous study.
What would you say were the most interesting findings of your summer research? Were there any surprises?
I found that NO2 and BC concentrations, surrogates of traffic pollution, decayed linearly first and reached a plateau at about 100m from the major road. This is consistent with previous studies conducted in other countries. The concentrations of BC, NO2, and PM10 for the cases were all higher than the concentrations for the controls. Even though not statistically significant, the absolute difference is relatively large. The associations of NO2 and PM10 with CHD were marginally significant. Each 10µg/m3 increment, NO2 and PM10 exposures were associated with 16% and 3% increase in the risk of CHD, respectively. The results were consistent with previous studies or our expectations.
What was the most challenging part of your summer research? Were you able to overcome these challenges?
One most inconvenient logistic challenge was that one of my instruments purchased from a company in New Zealand was held up by Chinese Customs when it was shipped from New Zealand to Lanzhou city. The equipment was considered as a sensitive object because they thought this equipment was imported as a company sample to be sold in China. I contacted Chinese Customs and Fedex multiple times, and filled out a lot of paperwork to file a claim for the equipment. After waiting a whole week and paying tax, I finally received my equipment. I was able to finish almost all the measurements that I planned.
Another challenge was collecting traffic data from the local government. Vector road maps (used in ArcGIS) are considered as confidential information in China and they are extremely expensive (about $80,000 per km2). The original plan was to use the distance between residence and major roads to estimate the exposures. Because it was impossible to purchase an official road map from the government, I selected a random sample from our cohort to measure traffic pollution at residence to do the above analysis.
Now that you are back on campus, what is the next step for your research?
Now I am trying to use open street maps to estimate the proximity to major roads from residence. The accuracy and completeness of open street maps in developing countries are uncertain. I will do more work to test the validity of using open street maps in the exposure assessment. Then the exposures of all the eligible births in our cohort will be included in our models to give more statistic power to our results.
Do you have any words of advice for graduate students who plan to do research abroad next summer?
I would suggest that they do as much preparation as possible. Even though you might be fully prepared, there are always some unexpected situations in the field. Detailed plans, such as housing, transportation, and work, should be made in advance if possible. Bring equipment with you as personal belongings. Once they are held up by Customs, you have to pay tax and do a lot of paperwork to get them back.