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What Can Danish Nurses Tell Us About Heart Health & Air Pollution?

Uncategorized Oct 14, 2021

Hi there. My name is Dr. Cameron Jones and I'm an environmental microbiologist and public health scientist.

And this week, we are talking about something that could potentially affect all of us. And the concept for this week's live stream is actually a colleague of mine who sent me an email telling me about a paper that he had just had published. And I thought that this is an absolutely fantastic publication that I want to draw all of my listeners and viewers' attention to. And the topic is, What Can Danish Nurses Tell Us About Heart Health and Air Pollution? And no, I'm not making a joke or focusing on a particular group of people for your amusement. This is a very serious piece of research and it is focusing on a large group of people and it has some significant implications for our heart health. And that's why I want to bring this to your attention.

So before I jump in and dive into some of the key research conclusions and how you can take advantage of this information in your own life, and certainly in your home and workplace to optimize conditions that select for better heart health, I want to go over some key facts and figures and to do that, I need to firstly, focus on where you can retrieve this publication for yourself. It appeared in the Journal of the American Heart Association this week. And if we dive into some of the statistics, because the context for this is around heart disease and the world health organization have put together a whole list of key facts and figures, which I need to explain, because this underpins the importance of this research from my colleague and cardiovascular diseases are a leading cause of death. 17.9 million people die from heart disease every year.

And this represents a staggering 32% of all global deaths and 85% of those deaths are due to heart attack and stroke. The big problem is that 75% of this cardiovascular disease occurs in low and middle-income countries. And most cardiovascular diseases are preventable by controlling for behavioral factors like tobacco use, obesity, poor diet, a lack of exercise, and alcohol abuse. Now, most of that sounds to be quite common-sense information here, but we need to drill into the different types of cardiovascular problems that can occur. And this particular study is focusing on something called heart failure. And the context for this and around heart failure is the very definition of what does this mean? Well, heart failure is the reduced ability of the heart to pump or fill with blood. And this affects 26 million people worldwide. And I've extracted a figure for your information here from one of the embedded references in the publication that just came out in the Journal of the American Heart Association.

And that is focusing on something called the prevalence of heart failure and the related concept of incidence of heart failure. And you can see in the table that there are two panels, one for incidence and one for prevalence. And you can see a range of different countries here with Australia right down the bottom.

So if I define prevalence and what this means, prevalence is the proportion of people who have a condition at some point in time whereas incidence is the right of persons who develop a condition at some point in time.

And if we look at the prevalence, this is people in the community, in our own community, in our own street and neighborhood and our workplace, we can see that the prevalence of heart disease for Australia is one to 2%. That means two people out of every hundred when you're walking around in the street, have heart disease at any point in time.

Now, these are staggering numbers, and we need to put this in perspective because heart failure and cardiovascular diseases are overwhelmingly behavioral issues. We can actually modify our risk factors. And I want to focus on the conclusions in this publication because you can take advantage of this information right now today. So what is this relationship with Danish nurses? Well, the question was, is there an association between long-term exposure to air pollution and road traffic noise with heart failure? Now, anyone who's been following this channel for any period of time knows that I am a passionate advocate for good indoor air quality. And why is this? Because so many of my clients and patient referrals come from doctors regarding their patients who are experiencing unexpected or unwanted problems due to, in many cases, exposure to water-damaged buildings and the mould and the spores in the air.

These are known as aeroallergens, but in all that mix of what's up in the air that we're breathing in all the time, there is another component and that's all the dust and debris and they have a size and there are certain conditions would contribute to this particulate matter, which make people particularly unwell. So I want to move forward to this particular paper and the relationship with the Danish nurse cohort. So what is the Danish cohort? Well, the experiment was designed to study the effects of hormone replacement therapy. Hence, why all the people in this cohort are females. They were all over the age of 44, and 22,189 participated in this research. Now it began in 1993 and then new recruits were added again in 1999. And the study ended at the close of 2014 in December. So in many cases, there is nearly a two-decade window where the scientists could examine the exposure to pollution and whether or not this was connected with the prevalence and incidence of heart failure.

And what the scientists did was that on enrollment of the Danish nurse cohort, they were given a comprehensive questionnaire, which included information regarding body mass, lifestyle, diet, work conditions, and things like that. And importantly, the nurses had their complete residential address history with dates tracked across the study period. And this is really interesting research because it's possible then to compare the ingoing and outgoing condition and relate this to environmental issues like pollution and the concentration of nitrogen dioxide and traffic noise. Because knowing this information gives you some control over it in your own life. And so the next information I want to bring to your attention is what did they measure? And then importantly, what did they discover? Well, they discovered that particulate matter and especially PM 2.5 was measured, like measured this since 1970 and the levels of nitrogen dioxide and nitrogen dioxide is given off from traffic, but also the burning of fossil fuels.

And they also looked at road traffic noise, and they then were looking at the exposure to particulate matter since 1990. And they had country-specific data for the amount of nitrogen dioxide and traffic noise since 1970. And they use that to overlay that information on all the other parameters they had for the nurses. And they discovered that of the 22,189 nurses, 484 of them developed heart failure. Now, that is 2% of the cohort. Now, look at this tremendously important overlap that the other publication that was also looking at heart failure across countries has also discovered even in Australia, we're matching this research at the one to 2% level. And this is really important to be aware of because the conclusion was that the enhanced risk of heart failure for nurses exposed to higher levels of all three pollutants. What else did the researchers discover?

Because you're probably thinking, "Okay, that makes sense." But they measured and mapped something called the hazard ratio. And this allows you to determine who in a community is the most vulnerable to exposure from fine particle 2.5 particulate matter. And they discovered that it is individuals older than 65, the obese, former or current smokers, people who have moderate to heavy alcohol consumption, those who did medium to high physical activity and look at this, people who are engaged in evening or night work. And if you look on the left-hand side, you can see where I'm extracting these data points for. They're the black dots on the graph. And you can also see that other problems like high blood pressure, diabetes, and living in suburban or rural areas also has a significant impact on your exposure to unwanted particulate matter. Now, where are we going with all of this?

Well, I suggest that you download and read the paper for yourself because there is some stunning information in here, which is breaking down the Danish nurse cohort in more detail than I am going into here, but I'm providing a helicopter overview of a couple of things, the deleterious or adverse impact of exposure to particulate matter, the adverse impact of traffic noise and the connection with nitrogen dioxide levels. But we can go a little bit further. And the conclusion and the hope for the future is that there are some clinical implications of these results as well. So the association with heart failure was strongest for those individuals exposed to PM 2.5 particulate matter. And this is suggestive that road traffic noise can be used in a sense like a biomarker. Obviously, former smokers and people with high blood pressure are more likely to suffer from adverse effects, from exposure to particulate matter 2.5.

And the key takeaway is that air pollution and road traffic noise can increase the risk of heart failure. Sounds pretty simple, doesn't it? However, these scientists took nearly two decades to carefully map these variables back to the prevalence of heart failure. Now, none of us want to be in these behavioral risks categories, but think for a moment about the importance of particulate matter, where are the sources of particulate matter in your home or workplace? What steps could you take to reduce your exposure? Are you living next to high traffic noise? Can you hear that? Are you already in a risk category? Could all of these factors contribute to your wellbeing? That's what I'd like you to think about, and I'll talk to you next week. Bye for now. See you later.


REFERENCES: 2021. Cardiovascular diseases (CVDs). [online] Available at: <> [Accessed 13 October 2021].

Lim, Y., Jørgensen, J., So, R., Cole‐Hunter, T., Mehta, A., Amini, H., Bräuner, E., Westendorp, R., Liu, S., Mortensen, L., Hoffmann, B., Loft, S., Ketzel, M., Hertel, O., Brandt, J., Jensen, S., Backalarz, C., Simonsen, M., Tasic, N., Maric, M. and Andersen, Z., 2021. Long‐Term Exposure to Air Pollution, Road Traffic Noise, and Heart Failure Incidence: The Danish Nurse Cohort. Journal of the American Heart Association,




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