Air pollution effects on chronic disease and the potential role
of the microbiome
Another important factor influencing inflammation from cardiovascular
disease, diabetes and chronic lung disease is air pollution. Increasing
evidence is showing a quite substantial effect, even when the air
pollution levels are below national standards[28–30], indicating a
direct or indirect effect on lung pathology and quite possibly the
microbiome. Although there are many potential effects of air pollution,
this pattern is compatible with a role for the colonization/infection of
microbes associated with air pollution, as described previously[12].
Little research has been done on this so far; however, changes in the
nasopharyngeal microbiota were observed after a severe haze event in
China[31]. It is also possible that hard-to-detect low-abundance
microbes from the rare biosphere may also produce pro-inflammatory
effects[12]. It has been observed that COPD exacerbations are often
related to exposures to certain gases and particulate matter[32]. It
seems possible that many of these gases and types of particulate matter,
especially from the burning of fossil fuel, may have microbial strains
associated with them that humans have not coevolved with. These
relatively novel, potentially non-coevolved microbes (PHM) might be more
prone to cause increased hypersensitivity reactions[12].
Not only are the above chronic diseases related to air pollution on a
long-term basis, but increases in air pollution in the short-term lead
to increases in emergency room visits, hospitalizations and
deaths[33], including deaths from respiratory infections[34]. It
is estimated that indoor and outdoor air pollution-related deaths
annually exceed 7 million[35].
Recent studies in the U.S. and Italy also support a significant effect
on mortality from COVID-19 from long-term air pollution
exposure[36,37]. These potential COVID-19 mortality effects and the
longer-term global effects mentioned above emphasize the need to reduce
the use of polluting fossil fuels for health reasons in addition to
avoiding the worst effects of global warming on many other facets of
human health and well-being[38]. Smoking reduction is important, but
it is also important to dramatically reduce and eventually eliminate
unnecessary wood/biomass burning and fossil fuel-related pollution by
adopting newer clean energy technologies.