Air stagnation

[2] Ground-level ozone and particulate matter originate from different sources and human activities such as power plants and refineries that pollute the environment around the affected area.

[4] Air stagnation becomes a significant issue in urban areas with high pollution sources because there is an increase in the amount of particulates that are being produced daily, causing prolonged events.

[1] In addition, urban areas can contribute to localized warming known as heat islands, that inhibit the dispersion of these pollutants and worsen air stagnation.

[1] Weather fluctuations may cause a lack of precipitation and storm systems that contribute to the pollutants being stagnant and persisting for an extended period of time.

[6] When substantial accumulations of smoke, dust, industrial emissions, or air pollution are predicted to occur close to the ground for a prolonged amount of time, the National Weather Service issues this product.

An example or air stagnation in Northern France, where a sheet of black, thick, and odorous smoke formed and stagnated for a few meters.