Common kinds of air pollution led to changes in teens’ blood pressure, study says
Jiachen Sun
News article: https://www.cnn.com/2023/02/08/health/pollution-teen-blood-pressure-study/index.html
Paper: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0279719
Air pollution has become a concerning threat to human beings. World Health Organization (WHO) suggests that 99% of the population lives in an environment with air pollution. the major pollutants consist of nitrogen dioxide, carbon monoxide, particulate matter, ground-level ozone, and sulfur dioxide, and most of those pollutants are generated by the combustion (except the ground-level ozone) of fuels due to wildfire, and transportation. Air pollution has been considered a cause of cancer and cardio-respiration diseases.
In this paper, the associations between NO2 and PM2.5 and blood pressure in teenagers from different ethnic backgrounds were examined. The researchers hypothesized "long-term exposure to modelled annual average air pollution would be associated with higher blood pressure." In 2003-2004, they recruited 6631 secondary school students, aged 11-13 years, from 51 secondary schools in 10 boroughs whose population has high proportions of people from ethnic minority groups. Those secondary school students are randomly selected from mixed-ability classes. Each school was selected to be represented at above or below the national average for academic performance. So, the sample is well representative. And in 2005-2006, 4,775 students took the follow-up measurement.
The Blood pressures were measured by trained and recertified fieldworkers following the protocols based on WHO’s manual. Systolic and diastolic blood pressure was measured at the participant’s school. The results show that the concentration of PM2.5 has a positive association with blood pressure. While the concentration of NO2 has a negative association with blood pressure. And both pollutants have a greater impact on girls than boys. Below of the graph shows the linear relationships. And there are no evident ethical associations.
The CNN article mentioned that a higher concentration of NO2 is associated with lower blood pressure, while a higher concentration of PM2.5 is associated with higher blood pressure among teenagers. In addition to the relationship found in the paper, the article successfully covered some key information in the paper, including the sample size of the study, the sources of the data the study used (Determinants of Adolescent Social Well-Being and Health Study), the consistency of the concentration vs. blood pressure relationship among different body sizes, socioeconomic status, and ethnicity.
I found the CNN article very satisfying because it provides a scientific background for ordinary readers. It mentioned what the NO2 and PM2.5 are, what causes those air pollutants, and what health impact those will have on people. In addition, it skips lots of statistical terms and grasps the key findings of the paper, making the articles digestible for non-scientific readers. I would like to give this article a 9/10. And the 1-point deduction is because the quote of people’s saying has no link attached to them. And I don’t know where those statements come from and whether they are true or false.
I agree that the news article succinctly summarizes the paper. Something that bothers me about the conclusions is the experimental design. Although I generally agree with how the study was performed, I would have liked to have seen a cross-comparison to children living in a more rural area. I wonder if the conclusions drawn in the paper (negative correlation between NO2 and BP and positive correlation between PM and BP) would have been similar to the lived environments. Is it that pollution itself is related to the BP, the foods students eat, or even their activity levels? Health studies correlations are complicated particularly for these reasons. Further, as this study was performed with student data from 2003–2004 and 2005-2006, I wonder what has happened to the students now as adults. A follow-up could be quite interesting.
ReplyDeleteThe author mentioned that "90 minutes exposure to NO2 (sitting next to a domestic gas cooker with gas hobs lit and uncovered) versus control (room air) acutely increased plasma [nitrite] and decreased blood pressure by ~5/5 mmHg" And the dietary intake of nitrate would also decrease blood pressure. The mechanism of PM raising effect is also given: "Apart from the inflammatory responses, exposure to higher PM concentrations may include disrupted circadian rhythms of renal sodium handling, as exposure to higher PM concentrations may reduce the ability of the kidney to excrete sodium during the daytime, leading to a higher night-time BP level"
DeleteFirst of all, I agree that the CNN article does a great job of presenting the science behind this article to the ordinary reader. As you said, this is well done by focusing on the key terms- what pollutants are studied, key findings, and health impacts- rather than getting bogged down in statistical methods that the reader will likely not understand. That is ultimately the goal of 'popular media' science. I think the most difficult part about a study like this, that Joe somewhat alludes to in his comment, is how many factors are readily at play and how we can accurately track the impact of any individual factor. Lifestyle choices (such as physical activity, which the authors make an attempt to factor into their study) also have a ton of impact on someone's blood pressure, but it seems like, with a large sample size, the effect of individuals who live at the extremes of any lifestyle choice can be somewhat mitigated by the sample volume. I think the most interesting unresolved part of this study was the idea behind air pollutants having a stronger effect on women because from my (extremely limited) knowledge in this area, there shouldn't be specific impacts of air pollution based upon gender. Being close to 20 years after the initial study (And ~18 after the follow up), a second follow up (Assuming accurate data can be tracked and incorporated) would be extremely interesting, but would ultimately depend on the willingness and memory of participants because it was not outlined originally.
ReplyDeleteA second follow-up would be very interesting. In addition, I am also wondering why females receive a greater impact from air pollution. However, that is not given in the paper.
DeleteJiachen, I agree with you in regards to the news article identifying the key motivations and findings from the scientific article; however, I would give the CNN article a 9/10 not because they made the scientific article digestible for others, but for communicating the findings of the scientific article in an eye-catching and in an environmentally urgent manner when the scientific article’s study/findings had a good amount of weaknesses and lacked conclusions that would be considered exciting or impactful that are usually included in news articles.
ReplyDeleteI found the scientific article to not be too dense for readers and believe non-scientific readers could’ve gotten through the scientific article slowly. I really like their motivation for their study (focus on a young kids/adolescents and the effect air pollution can have on the bloop pressure and overall development into adulthood) as well as their focus on ethnic differences between the adolescents and recognize the correlation between ethnicity/socio-economic disadvantage and public health. Their findings were not consistent with their hypothesis; however, I believe that their study still brings great attention for the need to study the impacts of air pollution for younger generations and the possible long-term consequences.
I think the article creates an effective and urgent voice by highlighting the symptoms of high blood pressure and the possible heath risks. I think by mentioning symptoms like “premature death” and “chronic disease” grabs the readers attention regarding air pollution and the necessary steps needed to help the environment. Even though the readers might not care between the difference of NO2 and PM, they still understand the risk of air pollution for younger generations.
What do you think of this? Do you think the article should’ve included a quote from an outside doctor [Dr. Panagis Galiatsatos] towards the end of the article? Did this help the journalist’s message?
By the quoting, I want to see the link directly to the interview where that professor mentioned that sentence. I think that it would be better for readers to explore this topic more.
DeleteI would agree that the CNN article does do a decent job of summarizing the key results of this study in a digestible and comprehensible form for most readers. I think it is important to make the general public aware of these sort of health concerns that may have gone under the radar for most people, but I am wary to fully support any claims made by the paper due to reasons mentioned by Theo and Joe. There are so many compounding factors for a metric like blood pressure that saying there is an association might not have very much tangible meaning. That isn't to say that pollutants have no adverse physiological effects, but proving a direct causal relationship is next to impossible. I agree with Theo's point that at a large enough sample size, variations in lifestyle should at least show a consistent pattern and/or trend, but with so many sociohistorical trends over the last several decades, how can we be sure that an increase in blood pressure isn't more correlated to an increase in socioeconomic stress endured by younger generations, or the realization of all that it takes to be an adult, or something else along those lines? Since the study tracked individuals from the age of ~11, blood pressure changes could also be due to natural physiological causes. However, I still do agree that this is an important area of research and that these findings are not only plausible, but likely. In that regard, I agree with Mia in that over-the-top phrases such as "premature death" is likely to grab any reader's attention, and whether or not pollutants cause adverse health effects, they cause adverse effects for the planet, so any reduction in pollution is a step forward. Like others have said, I also think a follow up sample of both the same participants and potentially new participants could be beneficial in elucidating the nature of this relationship.
ReplyDeleteYou have a good point! I agree that there are so many other factors that would interfere the blood pressure. And that would be risky to draw a causation relationship between blood pressure and pollution. And the paper does have an effect to encourage the public to reduce air pollution. And that is good!
DeleteI agree that the CNN article does a good job of summarizing the research paper, but I had a few concerns. First they should have added citations to the quotes, or at least linked to where they were getting them from, since they seem just randomly thrown in. I agree with Mia that they should have quoted an outside source, but really, it's weird that they don't talk about the effects of a higher BP at all. They talk about it like it's a bad thing without getting into the actual effects of it. I don't like how the CNN article uses a blanket statement when talking about the fact that there is no known reason for why girls might have a different BP than boys in their findings, but the research paper specifically says that in older children its because boys are more likely to have been drinking and smoking than girls which can cause heightened BP.
ReplyDeleteI also was curious about how they chose the sample population. It seems like they chose their population based on children in urban areas, but I would have liked to see some control studies done on children not living in highly polluted areas.
I agree that the CNN article is not doing that well in quoting and referencing other professor's statements. And in the paper, the effects on the health of having higher/ lower blood pressure are completely not mentioned. They should refer to other papers' conclusions about health effects.
DeleteThey choose sample basic from London city, and the town around London. I would agree that a study with samples from rural areas could be used as a control.
Also, thanks for finding that discrepancy between the paper and the articles.
Great job on the blog post. I agree with you that that the article does a very decent job of summarizing the paper and presenting in the information in a direct, yet interesting way. I like how the article explain why this study is important, then briefly explained the methods, followed by the main results and take aways. I can also appreciate how it mentioned some limitation, giving the reader all the proper information they need to make a decision on how they feel about this topic. The article I also think does a great job at giving some background and insight into NOx and PM2.5, really showing that it is possible to make science digestible to larger audiences. Like you mentioned, I think it would have been best to give links or in-text citation to where the quotes the author used came from as it would give a lot more credibility to the interpretation of the data. Also, I think the article lacks to acknowledge that there are a slew of factors that can cause fluctuation in BP. Nonetheless, I do think this is an important topic to discuss not only for public health reasons but also in terms of climate change. Overall, I agree with your 9/10 rating, and that there extensive use of quotes without direct citations is the main negative to the presentation of the results from the study.
ReplyDeleteGood analysis of the news article and corresponding scientific paper. After reading through I do agree that the CNN article does a decent job of summarizing the scientific findings in a bite-size manner. I think they were very effective at hooking in an audience and highlighting the way the findings of this research effects us (average Americans), because NOx and PM are real things that many of us are regularly breathing living in cities. This is a problem that many Americans will be alarmed about, so it's important that it's research is brought forth to the public! While this is important research to share, similarly to other commenters I believe that the source research paper has some shortcomings. Maybe I am missing something from the research paper, but if not I wish they would perform and discuss a study on the blood pressures of children in rural areas to more firmly establish that it is NOx and PM contributing. This would improve their scientific practice and make the data more concrete!
ReplyDeleteYeah! I agree that a study about blood pressure sampling teenagers from rural areas would further prove or disprove the conclusion made in this paper.
DeleteI agree with you that the CNN article was a good representation of the paper. The CNN article gave a broad summary of the paper's conclusion at an appropriate level of detail that is sufficient, but not overwhelming. Likewise, I think the CNN journalist gave good attention to the study's methodology, particularly with how they included the survey's limitations. I like how this article appeared to be written with a logos appeal, presenting facts from the study without a "click bait-y" spin, which many news articles seem to do. I think this style of writing encourages more trust in the scientific process as well.
ReplyDeleteRegarding the paper itself, I agree with others that it seems like there are a lot of confounding factors here. Id like to see if including samples from other boroughs of London & suburban/rural areas support the trends with NO2, PM2.5 on BP, or if other pollutants like O3 show similar trends in lower NOx environments.
I also think that further studies about the relationship between teenagers from rural areas could prove or disprove this trend. And this field just remain to be explore.
DeleteThis paper is quite intresting and I enjoy the way the CNN article summerizes it. I think the findings in the paper itself is quite intresting as certain pollutions can decrease blood pressure while others increase it. I would like to see a follow up on this paper itself and see how the impact of living in these areas affects individuals over time. I would also like to see how reproducible these results are and if they stand in different regions around the globe. The article is nice for scientific and nonscientific readers alike. I enjoyed the way the author did not shy away from non-popular opinions about the paper but included them. Overall a nice read.
ReplyDeleteI think it would have been great, as others have said, to see a bit more information regarding studies with a wider geographical scope. Perhaps it is too much to ask of a journalistic reporter not composing a longform piece, but I think offering a bit of clarity on the sourcing and limitations of the paper would have made the article a little more accessible.
ReplyDelete