Pollution and respiratory disease: can diet or supplements help? A review
The World Health Organisation (WHO) released a report in 2014 indicating that 3.7 million
premature deaths globally were attributable to ambient air pollution. Their data more than
doubled previous estimates and placed air pollution as the world’s largest environmental health
risk factor. The majority of outdoor pollutants come from anthropogenic sources such as vehicle
[5] emissions, fossil fuel combustion, forest fires and industrial processes including factory outputs. The
WHO showed that in urban areas which monitor air pollution levels, greater than 80% of people are
exposed to levels of pollution which exceed WHO limits. Primary pollutants can be divided into two
groups: particulate matter (PM) and gases (CO2, CO, NO2, NO, NOx, SO2). Secondary pollutants
such as ozone are formed from photochemical reactions between the primary pollutants, heat
[10] and UV radiation. Other environmental air pollutants of major public concern include polycyclic
aromatic hydrocarbons (PAHs) and aryl hydrocarbon receptors (AhR).
There has been increasing research on the effects of ambient pollution on health. Pollution
causes damage when it is in contact with the airways and skin. For example, some pollutants can
accumulate in the blood and be distributed in digestive organs, purely through inhalation. Pollutants
[15] also act on the exterior of the body and have been linked to the progression of inflammatory skin
diseases. Many studies have demonstrated the effects of exposure to environmental pollutants via
skin, inhalation or ingestion on morbidity and mortality.
The lungs rely on filtered air through the nose (with cilia and mucus attempting to filter/trap
unwanted particles) or unfiltered air via the mouth. Polluted air contributes to chronic obstructive
[20] pulmonary disease (COPD) prevalence and symptom onset. The idea that air pollution can
cause exacerbations of pre-existing asthma is supported by an evidence base that has been
accumulating for several decades, however it has more recently been suggested that air pollution
might cause new-onset asthma as well.[…]
In addition to outdoor air pollution, indoor smoke is a serious health risk for some 3 billion people
[25] who cook and heat their homes with biomass fuels and coal. Some 4.3 million premature deaths
were attributable to household air pollution in 2012. Almost all of this burden is in low-middle-income
countries. When indoor and ambient air pollution are combined, WHO estimates that, in 2012,
some 14% of deaths were due to COPD or acute lower respiratory infections, and 14% of deaths
were due to lung cancer.
[30] There has been recent publicity on the role of diet helping to combat the effects of pollution and
in this review we assess the role for diet in preventing the effects of pollution on asthma and other
respiratory diseases.
This text is part of a scientific article (a review) on respiratory diseases.
The main objective of this part of the article is to present how
