Health impacts of endotoxin-particulate matter inhalation, effects beyond cardiopulmonary toxicity

Exposure to high levels of particulate matter <2.5 µm (PM2.5) causes cardiorespiratory diseases due to oxidative stress and inflammation. The toxicity of PM2.5 depends on particle size and composition. PM2.5 can reach organs far from the lungs, such as the brain, heart, kidneys, and adipose tissue, affecting their function. Moreover, endotoxin, an important component of PM2.5, has recently been suggested as a risk factor for the development of metabolic, autoimmune, neurodegenerative, and renal diseases. Most published studies focus only on cardiorespiratory symptoms, airway inflammation, and impaired lung function. An amplified inflammation of the airways can transcend to other organs and cause genetic, biochemical, tissue, and physiological alterations. This review focuses on the role of endotoxin as an air pollutant, its adverse health effects, and the discussion on whether it should be considered as an air quality parameter.