Air pollution and mortality

The authors used a chemical transport model called GEOS-Chem to estimate the global exposure levels to airborne particulate matter derived from fossil fuel combustion. It’s a worldwide used model for estimating dispersion, for example the simulation of surface pollination. The model has been validated, meaning its predictions were compared with the reality and they matched. Levels of fossil fuels emission were inputted from publicly available data “from multiple sectors (power generation, industry, ships, aircraft, ground transportation, backup generators, kerosene, oil/gas extraction), detailed oxidant-aerosol chemistry, and reanalysis meteorology from the NASA Global Modeling and Assimilation Office” (page 5 of the manuscript). The mortality due to air pollution was computed by starting with the classical risk assessment analysis from epidemiological research and then adjusting for other variables like in-door particulate exposure (smoking) and so on. It sounds straightforward enough but the math and stats involved are very complicated. You have to take into consideration concentration, exposure time, and other factors that affect the outcome.

In addition, the authors calculated the mortality caused by fossil-fuel air pollution in children between 0 and 4 years of age, which was 876 in North America, 747 in South America, and 605 in Europe, annually. Pollution data is from 2012, mortality from 2015. The authors are hopeful that aggressive regulation designed to curb emissions in the last few years may have already lowered these numbers. Policy-makers, take note!

REFERENCE: Vohra K, Vodonos A, Schwartz J, Marais EA, Sulprizio MP, & Mickley LJ (Apr 2021, Epub 9 Feb 2021). Global mortality from outdoor fine particle pollution generated by fossil fuel combustion: Results from GEOS-Chem. Environmental Research, Volume 195, 110754. PMID: 33577774, DOI: 10.1016/j.envres.2021.110754, ARTICLE.

By Neuronicus, 11 March 2021

Stress can get you fat. And then kill you.

Some people lose weight under stressful conditions and some gain weight. How does that play into the risk for the cardiovascular disease and subsequent mortality? Medical doctors keep warning us that fat people are at risk for diabetes and heart disease. Turns out that being a little on the heavy side might actually not be that bad. It all depends on what kind of fat and where it is.

The paper featured today reviews a series of interesting articles with surprising results. Peters & McEwen (2015) identify three distinct phenotypes:

1) The good stress leads to well-proportionate body shape. People who live in safe environments, they do well socioeconomically, they have good self-esteem, and they have a fulfilling social and family life. They experience low levels of stress, they are well proportionate, and have a low mortality rate due to cardiovascular disease. Might as well call these ones the lucky ones.

2) The tolerable stress leads to corpulent-but-narrow-waisted body shape. People who experience stress but in order to cope with it they supply the brain with more energy by eating more. So they become more corpulent, gaining subcutaneous fat, but their cardiovascular mortality risk remains low.

3) The toxic stress leads to lean-but-wide-waisted body shape. People who experience prolonged stress exposure to uncertain socioeconomic conditions, poor work, or family life. They have low self-esteem, often associated with depressive periods. They are or become lean, but they accumulate large visceral fat deposits (as opposed to subcutaneous), and their cardiovascular mortality risk is the highest. They also are at risk for other physical and mental disorders. The phenotype 3 people have a wider waist relative to their body mass index and height.

Source: Peters & McEwen (2015, p.144)

Thus, the authors propose that instead or along with the body mass index, another metric should be used to identify the ones in dire need of help: the body shape index. Also, the review outlines the mechanisms responsible for these findings.

So next time you see a not so well-proportionate person, smile. Maybe even offer to help or chat; you don’t know what they’re going through.

Reference: Peters, A. & McEwen, B. S. (September 2015, Epub 3 July 2015). Stress habituation, body shape and cardiovascular mortality. Neuroscience Biobehavioral Reviews, 56:139-50. doi: 10.1016/j.neubiorev.2015.07.001. Article | FREE PDF

By Neuronicus, 5 October 2015