Air Pollution and the Airways: Lessons from a Century of Human Urbanization

Abstract

Since the industrial revolution, air pollution has become a major problem causing several health problems involving the airways as well as the cardiovascular, reproductive, or neurological system. According to the WHO, about 3.6 million deaths every year are related to inhalation of polluted air, specifically due to pulmonary diseases. Polluted air first encounters the airways, which are a major human defense mechanism to reduce the risk of this aggressor. Air pollution consists of a mixture of potentially harmful compounds such as particulate matter, ozone, carbon monoxide, volatile organic compounds, and heavy metals, each having its own effects on the human body. In the last decades, a lot of research investigating the underlying risks and effects of air pollution and/or its specific compounds on the airways, has been performed, involving both in vivo and in vitro experiments. The goal of this review is to give an overview of the recent data on the effects of air pollution on healthy and diseased airways or models of airway disease, such as asthma or chronic obstructive pulmonary disease. Therefore, we focused on studies involving pollution and airway symptoms and/or damage both in mice and humans.

Climate changes, air pollution and allergic diseases in childhood and adolescence

“…Primary pollutants are emitted directly by sources such as CO, SO 2 , and particulate matter (PM), while secondary pollutants form in the atmosphere due to chemical and physical reactions (O 3 , NO 2 , sulfates, and ultra-fine particulates). 6 They can be classified as gaseous or PM, depending on their composition. O 3 , nitrogen oxides (NOx), CO, CO 2 , volatile organic compounds (VOC), polycyclic aromatic hydrocarbons (PAH), and heavy metals are among the gaseous compounds.…”

“…O 3 , nitrogen oxides (NOx), CO, CO 2 , volatile organic compounds (VOC), polycyclic aromatic hydrocarbons (PAH), and heavy metals are among the gaseous compounds. 6 …”

“… 5 PM's gaseous compounds negatively affect the airways, and it has a significant impact on the respiratory system ( Table 1 ). 6 …”

“…The role of PM in understanding the damage of respiratory epithelial cells occurs via a toll-like receptor (TLR) 4 pattern recognition and/or TLR2 activation via NFk-B signaling and NLRP3 inflammasome resulting in induced production of the pro-inflammatory mediators – interleukin (IL)-1a, IL-1b, IL-6, CXCL8, and colony-stimulating factor (GM-CSF). 6 , 12 The PM 10 s and PM 2.5 s lead to the activation of the NLRP3 inflammasome via the production of reactive oxygen substances (ROS) and, consequently, alveolar macrophages, neutrophils, and dendritic cells. 6 , 12 Once processed by dendritic cells, the antigens will be introduced to T lymphocytes and, depending on co-stimulatory molecules released by dendritic cells, a Th 1 - or Th 2 -type immune response will be established.…”

The Health Impact and External Cost of Electricity Production

“…The coal-based energy sector, in addition to CO 2 emissions, emits other pollutants that directly affect human health, such as SO 2 , NO x , and particulate matter (TSP: total suspended particles, PM10: particulate matter with a diameter of 10 µm and below, and PM2.5 with a diameter of up to 2.5 µm). These pollutants cause many diseases such as cancer, heart attack, neurological problems, pneumonia, chronic bronchitis, and asthma, leading to hospital admissions and a reduction in life expectancy [7][8][9][10][11][12][13][14]. The observed human effects of various kinds result in measurable economic costs and losses (external cost), e.g., hospitalization cost, absence at work due to illness, or premature death.…”