Environmental scientists have been warning us for a long time that climate change and air pollution are having a negative impact on our health. However, medical research attempting to associate environmental factors with the risk of developing certain diseases is scarce.
Why is this? Perhaps medical researchers see environmental science as something outside their field of expertise. Perhaps it is easier to conduct research on molecules and genes in a laboratory environment. Perhaps the message of the negative impact of environmental factors on human health has not yet sunk in.
As published in Air Pollution and Health, Orru and colleagues conducted a review of 17 studies on the effects of climate change and air pollution on health.
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“All studies projected climate change to increase air pollution-related health effects,” they wrote. “Climate change will likely increase the concentrations of near-surface ozone and particulate matter, with associated adverse health consequences and with large uncertainties.”
This suggests climate change and air pollution are intricately linked. When one thinks of air pollution, one thinks of lung disease. This is not mere conjecture—there is hard evidence demonstrating how air pollution is indeed a risk factor for several lung diseases, including idiopathic pulmonary fibrosis (IPF).
‘An Overlooked Risk Factor’
In the Journal of Clinical Medicine, Majewski and Piotrowski called air pollution “an overlooked risk factor for IPF.” And in Environmental Health, Tomos and colleagues wrote “Long term personal exposure to increased concentrations of air pollutants is associated with increased risk of [acute exacerbations of IPF] in IPF patients.”
We live in the most polluted period in human history. World Health Organization (WHO) data indicate that 90% of people live in places where air quality exceeds the guideline limit of pollutants. The places experiencing this the most tend to be low-to-middle income countries. In addition, the WHO estimates that 7 million people die prematurely from air pollution globally each year.
The problem with air pollution is that it isn’t a one-off occurrence. Unlike with smoking, pollution does not stop when a cigarette is discarded. Instead, damage to the lungs happens again and again, with little time afforded for normal processes of healing to occur.
Read more about IPF patient education
“The chronic, repetitive, subclinical micro-injuries to the alveolar epithelium caused by the exposure to various noxious stimuli are leading predisposed individuals to subsequent dysfunction of the alveolar epithelium, which is central for the initiation and perpetuation of the pathogenic process in IPF,” Majewski and Piotrowksi wrote.
An Amplifier of Lung Injury and Fibrosis
A key hypothesis about the pathogenesis of IPF is that repetitive micro-injuries to the alveolar epithelium trigger a set of reactions that causes the excessive production and accumulation of interstitial fibrosis. The lungs are unable to keep up with the repeated need to restore normal lung architecture, leading the normally structured alveoli to be replaced by extracellular matrix.
Tomos and colleagues conducted a study to investigate the relationship between long-term personal urban air pollution exposure particles and the occurrence of acute exacerbations of IPF. They recruited 118 consecutive IPF patients and collected information on smoking status, demographics, and medical history.
The research team then estimated personal long-term exposure to air pollutant concentrations for each participant based on their geocoded residential addresses. They used maps with predicted annual average of ozone (O3), nitrogen dioxide (NO2), particles with a 50% cut-off aerodynamic diameter of 10 mm (PM10), and particles with a 50% cut-off aerodynamic diameter of 2.5 mm (PM2.5). Based on the estimated air pollution of their geocoded residential addresses, the researchers were able to assign air pollution exposures to participants retrospectively.
Read more about IPF epidemiology
“We detected positive significant associations between AE-IPF and a 10 μg/m3 increase in previous-year mean level of NO2, PM2.5 and PM10 independent of age, gender, smoking, lung function and antifibrotic treatment,” Tomos et al wrote.
The findings of this study suggest that repetitive chronic lung injury from air pollution invites inflammatory responses that cause acute exacerbations of IPF to occur. Air pollution acts as an amplifier of lung injury and the fibrotic processes that accompany it.
Searching for Solutions
What can be done to shield vulnerable populations from air pollution? Unfortunately, there are no easy solutions. Other risk factors for disease, such as an unhealthy diet or cigarette smoking, are lifestyle choices that can be eliminated with the help of professionals. But what can be done when the risk factor (ie, air pollution) is all around?
“Because there are very limited options for reducing human vulnerability to air pollutants, protecting population health under future warmer climates will require regulatory interventions such as reducing greenhouse gas emissions,” Orru and colleagues wrote.
To overcome the harmful effects of environmental pollution on human health, governments and the populace must work together and continue to do so for the long term.
References
Majewski S, Piotrowski WJ. Air pollution—an overlooked risk factor for idiopathic pulmonary fibrosis. J Clin Med. 2020;10(1):77. doi:10.3390/jcm10010077
Orru H, Ebi KL, Forsberg B. The interplay of climate change and air pollution on health. Curr Environ Health Rep. 2017;4(4):504-513. doi:10.1007/s40572-017-0168-6
Tomos I, Dimakopoulou K, Manali ED, Papiris SA, Karakatsani A. Long-term personal air pollution exposure and risk for acute exacerbation of idiopathic pulmonary fibrosis. Environ Health. 2021;20(1):99. doi:10.1186/s12940-021-00786-z
Air pollution. World Health Organization. Accessed August 13, 2022.
