I have written before about the danger of breathing air pollution, especially diesel particles from cars and trucks.

Extensive research in both humans and animals demonstrates that regular breathing of polluted air can cause inflammation in a number of organs, such as the heart, liver, and brain.

In fact, heart failure rates are higher in people who have been exposed to diesel exhaust fumes, and suggestive links have also been shown for such conditions as Alzheimer’s dementia and Parkinson’s disease.

Researchers looked at the effect of exposure of pregnant mice to either fresh air or diesel-polluted air on the mice’s offsprings’ brain inflammation and on obesity later in life.

The baby mice exposed to fresh air had very little brain inflammation, whereas the ones exposed to polluted air had high levels of brain inflammation.

As a second part of the study, the researchers then gave the mice either a low-fat diet or a high-fat one. The mice exposed to the polluted air and later a high-fat diet gained 340 percent more fat than did the ones exposed to fresh air.

In males, the combination of the exposure to polluted air while in the mother’s womb and later eating a high-fat diet resulted in sluggish behavior and more anxiety than the ones exposed to fresh air or a low-fat diet.

The males exposed to the pollution also had insulin levels that were 450 percent higher than the fresh-air males. A high insulin level is related to excessive fat gain.

What this study shows is that polluted air exposure during pregnancy can cause significant microglia activation in the brain of the baby and that this then programs these brain immune cells to overreact when a second immune event happens later in life — such as eating a high-fat diet.

It should be noted that the high-fat diet contained a mixture of omega-6 oil (soybean oil) and lard, a saturated fat. Omega-6 fats increase brain inflammation.

More people live in crowded cities than ever before, and the trend for urban living is growing.

One of the most hazardous activities is jogging or bike riding along city streets. The exercise enthusiast is already producing high levels of free radicals due to the exercise and adding the pollution greatly magnifies the inflammatory effect on their bodies.