Podcast: Chronic Respiratory Disease

Published May 8, 2023

In this episode of Global Health Insights, were joined by Dr. Sara Momtazmanesh to explore the impact of air pollution and smoking on chronic respiratory diseases, particularly for people in East and South Asia.

Key takeaways:

  • Chronic respiratory diseases (CRDs) are the third-leading cause of death globally, affecting around 1 in 20 people. Rates are highest in East and South Asia, mostly due to higher levels of air pollution, which was found to be a leading risk factor for CRDs, alongside smoking.
  • Nepal has the highest mortality rates in the world from chronic respiratory diseases, caused predominantly by household air pollution from burning solid fuels. Its essential to provide clean cooking energy resources to households in Nepal and similar countries in order to tackle this issue.
  • On average, men are more susceptible than women to CRDs, due to higher rates of smoking and greater likelihood to be exposed to occupational risks like hazardous dust and asbestos.

Read the research

This transcript has been lightly edited for clarity.

Pauline Chiou: Hello and welcome to Global Health Insights. This is a video podcast, by the Institute for Health Metrics and Evaluation, tackling some of our biggest health issues. Im Pauline Chiou in Media Relations. And in this podcast, we are going to be talking about chronic respiratory diseases, or CRDs.

Id like to introduce our guest, Dr. Sara Momtazmanesh, who is joining us from Tehran. Shes a collaborator with IHME, and also a researcher at the Tehran University of Medical Sciences.

Dr. Momtazmanesh, thank you so much for being with us. Ill jump right in. You just published your new research in The Lancet eClinical Medicine journal on CRDs. What are the key findings from your research?

Dr. Sara Momtazmanesh: Thank you very much for having me. Well, chronic respiratory diseases, or CRDs, continue to pose a significant challenge to the public health as they are the third-leading cause of death globally. While there has been a significant reduction in the burden of CRDs, with a 30% reduction in death rate, still approximately one in every 20 people are suffering from CRDs.

These findings indicate that there is a significant need for prevention, treatment, and diagnostic strategies to improve the care of CRDs, in order to prevent incidence of chronic respiratory diseases. I would also say that we found that South Asia and East Asia had the highest mortality rates due to chronic respiratory diseases. 

We found that men were more likely to have had a higher death rate from chronic respiratory diseases compared to women. Notably, death rates from occupational risks were three times higher in men when compared with women. We found that tobacco smoking and air pollution were the two leading risk factors for death from chronic respiratory diseases.

Pauline Chiou: Doctor, you mentioned a lot of information for us to digest, and lets break it down. And, starting with geographic regions, you had said that East Asia and South Asia have the highest rates of mortality from chronic respiratory disease. So whats going on in those regions?

Dr. Sara Momtazmanesh: Well, in those regions, its important to consider the role of air pollution as it plays a significant role. For instance, in East Asia, the mortality rate attributed to air pollution is almost three times higher than the global rate.

Its important to note that, for instance, Nepal, a country located in South Asia, has the highest mortality rate from chronic respiratory diseases.

Air pollution has two main components, ambient air pollution and household air pollution. For East Asia, we see that the leading risk factor is ambient air pollution.

On the other hand, for Nepal, we see that the major component constituting the burden from air pollution is household indoor air pollution, and that arises from burning household solid fuels, such as charcoal, wood, or coal, and burning these fuels produce hazardous substances that can injure the lung.

Previous studies have shown that more than half of Nepalese households do not have access to clean cooking energy. So its very important to provide this country and similar countries which are located in sub-Saharan Africa with clean cooking energy resources, and to tackle this issue in these regions.

Pauline Chiou: So if youre talking to policymakers in these parts of the world, East Asia or Nepal, in South Asia, or sub-Saharan Africa, which you just mentioned, what would you recommend needs to be done in terms of minimizing household air pollution? And then from the other point of view, you mentioned ambient air pollution in East Asia. What are some policy recommendations there?

Dr. Sara Momtazmanesh: Well, for indoor household air pollution, its important to encourage using clean cooking energy and using more efficient stoves. So its important to improve public awareness on the possible harms of those hazardous fuels, and their emissions, and their potential harms on the individuals health.

It's also important to improve indoor ventilation, to reduce the concentration of those hazardous dusts inside the house.

Additionally, its important to provide these countries with more efficient stoves, and with cleaner fuels. Its important to encourage them to use, for instance, electricity or LPG [liquified petroleum gas] instead of the solid fuels that they are using.

For ambient air pollution, I think that the most important critical strategy would be to control the emissions from industries and transportation by implementing a strict regulation on air quality measures, and monitoring the air quality.

Its important to have strong and strict air quality standards, and it’s important for countries to try to adhere to the standard. Additionally, using solar power or wind power can help us to reduce our reliance on solid fuels that tend to produce emissions and tend to pollute the air.

Pauline Chiou: So its a very complex situation, and youre offering different solutions for policymakers on approaching it from different angles. Theres another theme that you saw in your research, and that was gender disparity, where men are impacted more than women by chronic respiratory disease, whether its smoking or occupational work hazards such as breathing in asbestos, or air pollution. Can you explain what you saw in terms of this difference?

Dr. Sara Momtazmanesh: Well, as you kindly mentioned, we found that men had higher mortality rates from chronic respiratory diseases, and this gender gap was more prominent for chronic obstructive pulmonary disease and pneumoconiosis.

Traditionally, men were more likely to use tobacco, and this difference in smoking habits may explain this gender gap in some part.

Overall, these differences can be because of different societal roles, different occupational roles, and different habits. Its important to notice that the smoking habits are gradually changing, with a rising percentage of women using tobacco, so we might see a change in these trends in the future.

You know, we have seen other investigations, that are out of our investigation’s scope, showing that women are even more likely to develop more severe lung dysfunction, for a given exposure to tobacco, compared to men. So these trends may change in the future, and we need to monitor these trends in the future.

However, for occupational risks, men are more likely to work in industries that might involve some hazardous dusts, and that might justify the increased mortality rate from occupational risk, and occupational dust in men, compared to women.

Pauline Chiou: And to carry on that theme of the gender disparity that you saw in your research, this is the first time that the Global Burden of Disease uses body mass index, or obesity, in terms of highlighting that as a factor. And it was the leading risk factor for asthma, especially in women. Can you explain the connection to us?

Dr. Sara Momtazmanesh: Yeah, the relationship between obesity and asthma has been extensively studied. It’s been discovered that obesity is associated with an increased risk of developing asthma.

Obesity can also result in comorbidities such as obstructive sleep apnea or type 2 diabetes, which both can increase the incidence of asthma as well. Several mechanisms can explain the relationship between BMI and asthma. Excessive body weight, for example, can cause increased airway inflammation, which can contribute to the development of asthma. Additionally, its important to note that obesity is usually causing an inflammatory effect in the body, which can further promote the hyper-responsiveness of the airway in asthma. 

As you kindly mentioned, according to our study, high BMI is the leading risk factor for fatality from asthma in women. However, in men, it stood as the second-leading risk factor, following tobacco use.

So this can have several reasons. First of all, different smoking habits between men and women can justify this finding, but additionally, effects of sex-specific differences, such as hormonal differences, can justify this finding and this difference between men and women.

Pauline Chiou: Its fascinating research that youve done and in your teasing out so many important themes. Finally, I want to talk about climate change. How has climate change impacted chronic respiratory disease, because that is a threat that youve had your eye on?

Dr. Sara Momtazmanesh: Well, climate change has a significant impact on chronic respiratory diseases, and it has its impact through two main mechanisms.

First of all, it can raise the amount of pollen and allergens produced by plants, as well as the concentration of ozone and particulate matter at the ground level.

But moreover, as we know, the earth’s temperature is rising due to climate change, and this is the first iteration of the GBD that contains non-optimal temperature as a risk factor.

So, as we found, many previous studies have also shown that high temperature can be associated with more severe disease course in chronic obstructive pulmonary disease, and can be associated with increased mortality in patients with COPD.

Its important to note that this highlights the critical role of climate change on public health, and it highlights the need to tackle this issue.

So not just smoking, not just asthma, not just occupational work hazard situations, but also climate change is something that is a factor in this health challenge.

Pauline Chiou: Dr. Sara Momtazmanesh, thank you so much for really putting a spotlight on chronic respiratory disease, and we see that it truly is a global health issue. Thank you so much.

Dr. Sara Momtazmanesh: Thank you very much for having me.


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