Figure 1. Schematic representation of Li et al.'s findings.

From the left, clockwise: (1) Landscape fires release particulate matter into the air, including particles measuring less than 2.5 microns in diameter (PM_2.5). A magnifying glass shows how much smaller these particles are compared to the width of a strand of human hair (these particles are 2.5 microns or smaller; a hair is 60 microns) (2) Breathing in these tiny particles during pregnancy draws the particles deep into the lungs, where they lead to irritation and inflammation and enter the bloodstream affecting other organs, as well as the growing fetus. (3) When the baby is born, it weighs less than its siblings, who were exposed to lower levels of PM_2.5 during pregnancy.