The Intimate Connection Between Pollution, Climate Change & Lung Health

As physicians, we are tasked with addressing the downstream effects of dangerous trends in society, such as the use of tobacco or the worsening quality of our air. One physician pushing back against this status quo is Heather Zar, M.D., Ph.D., a doctor on the faculty at the Red Cross Children's Hospital in Cape Town, South Africa, who through innovative research is bridging not only the wide gap between public policy and the role of doctors but also the gaps between rich and poor and between developed and developing countries.

Drakenstein is an area just inland from Cape Town, on South Africa's eastern coast, and as in most of the country, many of the inhabitants of the region are poor, live in a semi-urban environment, and are exposed to a multitude of indoor pollutants and infectious agents. Zar and her colleagues chose Drakenstein, but in reality, the study could have been conducted in almost any part of South Africa, or in any other African nation: the continent accounts for just 18 of the global under-five population but 42% of total deaths for this age group each year.

Zar and her colleagues decided to study the children even before they were born. Potential effects on a child's lungs are known to start in utero, so Zar's team enrolled mothers who were 20 to 28 weeks into their pregnancies, with a plan to study their children's habits up to the age of 5, as well as the habits of their mothers and their entire households.

A term that emerged in the late 1990s, microbiome is defined as the collection of microorganisms that live in a particular environment, including in and on humans. We have always known about bacteria living in the human gut and on the skin, but newer molecular techniques have allowed us to catalog the vast number and scale of organisms living in every organ of the human body. Overall, some ten thousand trillion organisms live in every human; for each one of our cells, there is a microbial cell that lives in and on us. The vast majority of these organisms live in the large intestine, but some inhabit organs previously thought to be sterile, such as the bladder and the lungs.

Today, we know that hundreds of species of bacteria colonize our lungs, including Provatella, Fusobacterium, and Streptococcus, along with fungi, such as Candida and Saccharomyces. Many of these bacteria and fungi clearly perform important functions, primarily keeping other harmful bacteria out by producing inflammatory proteins that both kill invading bacteria and induce the lung cells to produce bacteria-fighting proteins.

Knowledge of the microbiome is forcing scientists to rethink how lung diseases occur as well as how they might be treated.

Those patients with COPD1, cystic fibrosis2, and asthma3 have all been shown to have very different lung bacteria compared with subjects without lung disease, likely making them more susceptible to other seasonal infections. We also know that exposure to household air pollution significantly changes the populations of bacteria in the human lungs, and smoking alters this microbiome in the lungs, nose, and throat.

With 1,140 mother-child pairs having completed one full year in the study in 2016, some definitive results of the Drakenstein Child Health Study have already been reported. They showed that many children were being raised in a toxic environment—one-third of the women smoked while pregnant, and 56% of the newborns had detectable cotinine (a nicotine byproduct) levels in their urine samples. There were also high levels of biomass fuel exposure in the homes.

The rates of pneumonia were elevated in the cohort as a whole, despite all the babies being appropriately immunized. Among the babies who contracted lung infections, their lung function, measured at one year of age, was lower than that of children who were able to remain infection-free (adults with pneumonia generally recover all of their previous lung function, barring a very severe infection).

Decreased lung function is known to put children at increased risk of contracting pneumonia again, as well as developing asthma. But there are other implications for these children beyond the lungs. Data clearly shows that decreased pulmonary function in adults leads to more dementia and cognitive impairment4 later in life. Some findings on this effect in children are emerging, too, and the Drakenstein Study team plans to add to this information by examining MRI brain scans of some of their subjects to find out if respiratory infections and pollution influence brain development.

If the answer is yes, it would provide another important reason to start cleaning up the air that we all breathe.

Addressing climate change and embracing clean energy sources will be a major part of our effort to improve air quality after recent setbacks. In the face of such enormous challenges, the goal of clean energy sounds almost quaint. But if we manage to make a total commitment to clean energy sources, we could accomplish something for the first time in the thousands of years of our civilized existence: living an advanced lifestyle without polluting the air that we breathe.

And if we are able to achieve this goal, we will go a long way toward keeping our lungs and bodies healthy.