The Eiffel Tower was barely visible amidst a think blanket of smog that descended on Paris and other parts of northern France on Wednesday.
The dangerous spike in air pollution prompted authorities to take emergency measures such as lowering speed limits and banning trash fires as the French air quality monitoring agency Airparif raised its air pollution alert to its second-highest level.
Airparif blamed the smog on seasonal weather patterns and emissions from farms and vehicle traffic. An area of high pressure has trapped the smog in the atmosphere over northern France. That high pressure area caused sinking air, trapping pollutants and haze in the lower levels of the atmosphere. This, combined with recent cold, wet weather has led to high levels of polluting compounds such as ammonium nitrate.
The agency measures the concentration of particles with a diameter of 10 microns or less. These particles are dangerous because they can lodge deep inside human lungs and and cause breathing problems for those with asthma, as well as cancer, in cases of long-term exposure.
The safe limit for these PM10 particles is 80 micrograms per cubic meter. On Wednesday, Airparif forecast maximum levels to reach between 80 and 95.
A similar influx of air pollution hit Paris around the same time last year, leading authorities to impose limits on the number of cars allowed on the road. At the time, it was the worst air pollution event to hit Europe since 2007.
The onset of the smog comes months before the city is set to host a pivotal United Nations conference on climate change in December.
