Global Respiratory Health

 

Do people born more recently have better lung function than earlier generations?

A recent study using data from 28,569 adults across 34 countries in the Burden of Obstructive Lung Disease (BOLD) study found that people born in more recent decades generally had better lung function than those born earlier.

What did the analysis find?

Participants were born between 1902 and 1976 and had completed spirometry at recruitment. Across time the forced vital capacity (FVC), the forced expiratory volume in 1second (FEV1) and the ratio FEV1/FVC improved across birth cohorts.

Even after accounting for factors such as age, height, smoking, body weight, education, occupational exposures and previous tuberculosis, people born later continued to have higher lung function.

The findings were both seen in high-income countries (HICs) and low- and middle-income countries (LMICs), as well as among men and women and people with different smoking histories.

 

 

Figure 1 Birth cohort effects on post-­ bronchodilator lung function. Post-­ bronchodilator lung function by age group, country income group and birth cohort. Each marker represents the subgroup-­ specific mean of lung function values, and linear trendlines are shown. FEV1, forced expiratory volume in 1 s; FVC, forced vital capacity.

Why might lung function be improving?

Birth year itself does not make someone’s lungs healthier. Instead, it may reflect the conditions experienced by different generations.

However, our study cannot tell us which of these factors caused the differences. It shows an association between later birth year and higher lung function, not a direct cause-and-effect relationship.

 

Figure 2. Plausible factors explaining the improvement in lung function over time.

 

Why does this matter?

Lung function tests are interpreted by comparing an individual’s results with expected values. If lung function has changed across generations, reference standards based on older populations may not always reflect what is typical for people born more recently.

What should we take away?

The findings highlight that lung health is shaped over a lifetime and may reflect improvements in health and living conditions across generations. More long-term research, particularly in LMICs is needed to understand what is driving these generational changes.

Want to know more? Read our paper now published in Thorax

Written in collaboration with Dr Jixuan Ma

Read Born Later, Breathing Better? How Lung Function Has Changed Across Generations in full

We often think of smoking and air pollution when we talk about lung health. But what about the air we breathe for hours every day at work?

A recent analysis of data from the multinational Burden of Obstructive Lung Disease (BOLD) cohort study suggests that what we breathe at work, particularly dusts, fumes, gases and pesticides, may affect our lung health.

This analysis was based on 4,237 adults from the general population across 17 sites, mostly in low- and middle-income countries (LMICs), that were followed for a median of around 10 years. Each of them had their lung function measured using spirometry. By looking at the jobs each participant had throughout their life, we estimated their exposure at work to potentially harmful substances, including vapours, gases, dusts and fumes (VGDF), pesticides, solvents and metals each participant had been exposed at work.

So, what did we find?

People with greater occupational exposure to VGDF showed a larger decline over time in the ratio between two lung function parameters (FEV₁/FVC). This ratio tells us how easily air can be blown out of the lungs; falling values can be a sign of increasing airflow obstruction, which is typical of diseases such as asthma and chronic obstructive pulmonary disease.

Pesticides stood out too. Higher pesticide exposure was linked not only with a greater decline in lung function, but also with wheezing. Those in the high-exposure group had a much higher risk of wheezing compared with those with little or no exposure.

Interestingly, we did not find similar associations for solvents or metals, and the results were broadly similar in men and women.

Why does this matter?

For many people, occupational exposure isn’t occasional; it can mean breathing the same dusts, fumes or chemicals for decades. This may be particularly important in LMICs, where occupational exposure limits and workplace protections may be less consistently implemented or enforced.

While the study included a large and diverse multinational population, there are some limitations. Workplace exposures were estimated rather than directly measured, and lung function was measured only once at follow-up. There was also substantial loss to follow-up, partly due to the COVID-19 pandemic. These factors mean the findings should be interpreted with some caution, and further research is needed to identify which specific workplace exposures pose the greatest risk

The takeaway message: The air we breathe at work matters.

Smoking remains an important cause of chronic lung disease, but it isn’t the whole story. These findings reinforce the importance of reducing harmful workplace exposures and monitoring respiratory health, particularly among workers in high-exposure settings. Sometimes protecting lung health is not just about smoking; it’s also about making sure the places we work are safe to breathe in.

Read the full paper

The findings of this study were published in the peer-reviewed journal BMJ Open Respiratory Research. The article can be freely accessed and read here: https://bmjopenrespres.bmj.com/content/13/1/e004213

Read Your job and your lungs: What a 10-year study found in full

Same job, different health outcomes

Why do some people develop lung problems after years of workplace exposure while others do not? Two workers might share the same job, be exposed to the same harmful substances, yet only one goes on to develop lasting lung damage.

Exploring the early stages of lung disease

Small airways obstruction (SAO) is an early and often silent sign of chronic obstructive respiratory disease (COPD). SAO reflects the narrowing of the small airways of the lungs and can appear many years before it progresses to the large airways or presents with respiratory symptoms. Understanding these early signs of disease is important in preventing chronic lung disease later in life.

Combining genetics and workplace exposures

Using data from more than 147,000 UK Biobank participants, we conducted a genome-wide association study (GWAS) to identify genetic variants associated with SAO. We then investigated whether these variants interact with occupational exposures to modify the risk of SAO.

 

What are the key messages?

• We identified 36 genetic variants associated with SAO.
• Eight variants significantly interacted with occupational exposures.
• Workers carrying two copies of the most common allele were more likely to develop SAO when exposed to pesticides, vapours, gases, dusts and fumes (VGDF), or metals, as compared to those with no copy of the common allele and not subjected to these occupational exposures.

In other words, some genes appear to amplify the harmful effects of occupational exposures.

Clues from lung tissue

Two genetic variants (rs9273529 and rs644045) were also moderately linked to gene expression in lung tissue, hinting at potential biological mechanisms. These may help explain how occupational and environmental agents trigger inflammation and damage in the lungs in some individuals but not all. However, future research is needed to confirm this.

 Why is this study important?

Our findings highlight the complex interplay between genes and environment in determining who develops SAO. Recognising these interactions could help identify workers who are more vulnerable to certain exposures and guide targeted prevention or monitoring strategies. However, this must be used ethically and responsibly. The path to better lung health lies not only in reducing harmful exposures but also in understanding how genes affect lung health.

Read Genes, Jobs, and Lungs: The Hidden Interplay Behind Respiratory Health in full

Read Genes, Jobs, and Lungs: The Hidden Interplay Behind Respiratory Health in full

Tiny Airways, Big Impact

The damage of the small airways of the lungs can result in inflammation, structural changes, and increased airway resistance. This is a common characteristic of chronic respiratory diseases such as asthma or chronic obstructive pulmonary disease (COPD). While the small airways of the lungs may not be the star of the show, they are a crucial part of the lung health story.

Spirometry: The Lung Detective

Small airways obstruction (SAO) can be detected using spirometry. Traditionally, the mean forced expiratory flow rate between 25% and 75% of the forced vital capacity (FEF_25-75) is the preferred parameter. However, novel parameters such as the forced expiratory volume in 3 seconds as a ratio of the forced expiratory volume in 6 seconds (FEV₃/FEV₆), have proven effective at detecting SAO.

We know that chronic respiratory diseases are leading causes of mortality around the world. Can SAO, even without ticking all the boxes for a doctor diagnosis of respiratory disease, predict death?

The big UK Biobank Study: What did we find?

We analysed the data of over 250,000 participants from the UK, who had high quality spirometry, and found some novel results:

• About 24% of participants had SAO. Among these, about 10% had isolated SAO, meaning their small airways were obstructed, but their larger airways were not.
• People with SAO had increased risk of death from all causes, including respiratory diseases, cardiovascular diseases, and cancers. The risk was especially high for respiratory diseases, with more than double compared to those without SAO.
• Even without respiratory disease (isolated SAO), the mortality risk was increased for cardiovascular diseases and cancers. Importantly, these findings were also true among people who have never smoked, indicating that SAO itself, regardless of smoking, is a critical factor.

  

Why should we care?

1. Early Detection: Catching SAO early could be crucial in preventing more severe lung diseases later in life.
2. Lifestyle Factors: Smoking is a big no-no for lung health, but even people who have never smoked can have SAO. This is likely to be caused by other factors.

While the UK Biobank cohort’s lack of representativeness and the relatively short follow-up period pose limitations, the study’s large sample size adds significant weight to the findings. Future research should aim to replicate these results in more diverse populations and explore the underlying mechanisms linking SAO to increased mortality.

Take home message.

Understanding and detecting SAO can give us a head start in managing chronic respiratory diseases such as COPD and asthma. Ultimately, this can aid to reduce respiratory morbidity worldwide. The findings of this study were published in the peer-reviewed journal CHEST. The article can be freely accessed and read here: https://doi.org/10.1016/j.chest.2024.04.016

Read Unmasking the threat of small airways obstruction in full