Cold winters create more pollution . This is the conclusion reached by Swedish researchers after studying how when low pressures are located over southern Europe and displace cold air from the polar regions or from Siberia, the concentrations of nitrogen oxide (NO and NO2) in the atmosphere increase. , reducing urban air quality.
Apparently, it all depends on the North Atlantic Oscillation (NAO) , which is a fluctuation in the pressure difference at sea level that occurs between the low pressures of Iceland and the high pressures of the Azores. . When the NAO is positive (NAO +), which is the most common in winter, the winds from high latitudes circulate strongly from west to east – parallel to the equator – and prevent the cold generated in the Arctic from spreading to other areas. When this happens, the storms that form in the Atlantic find a favorable corridor to advance and give rise to the traditional rainy and rather mild winters of London and other cities in Europe. However, when the NAO has a negative phase (NAO-), the cold invades Europe and the pollution that accumulates in the air increases considerably , according to the authors of the study in the journal Atmospheric Environment .
