These photos were taken in the city of São Paulo/Brazil, on a foggy morning in late autumn, 2017.

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Fogs often occur when dust particles are accumulated in relatively dry air and weather conditions block the spread of smoke and other concentrated pollutants, forming a low mantle that impairs visibility and can become a respiratory threat.

 

Smog is the term used to define the accumulation of air pollution in big cities, forming a large haze of smoke in the atmospheric environment near the surface. The word smog is precisely the junction of the English words smoke and fog. This phenomenon impairs air quality and also decreases visibility in urban environments. Smog usually forms in big cities, where air pollution is high and mainly caused by the burning of fossil fuels (gasoline and diesel) by motor vehicles. In the most extreme situations, due to the low visual conditions, it makes infeasible ground traffic for vehicles and also for airplanes and helicopters.

 

Sao Paulo is the most populous city in Brazil, the American continent and the entire southern hemisphere, with about 21 million inhabitants in the metropolitan region. In a city of this magnitude, pollution is a big problem. A 2013 study found that air pollution in the city causes more deaths than traffic accidents (which are not few).

 

Are we seeing?