Fireworks likely caused weekend pollution spike

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Twin Cities Air Quality Index shows a dramatic spike in particulate matter over the 4th of July weekend.

Did you notice the smell of fireworks overnight Saturday night into Sunday morning? Many metro residents did. The smoke was so thick at the Weather Lab late Saturday night we had to close the windows.

Air pollution monitors in the Twin Cities detected a dramatic increase in fine particulate matter Sunday as light winds and stagnant air allowed pollutants to accumulate. The only reasonable explanation for the increase is smoke from fireworks displays on the 4th of July.

The boost in the MPCA’s Air Quality Index (AQI) numbers Sunday was significant. From June 27th through July 2nd The Twin Cities enjoyed good air quality with AQI readings in the 30s and 40s.Then on July 3rd AQI readings rose to 51. They rose again to 81 on the 4th, followed by a spike to 124 on the 5th before improving to readings back into the 50s today.

Since vehicle emissions generally drop on the weekend, the only logical explanation for the pollution spike is municipal and home fireworks displays. Weather conditions featured light winds and stagnant air. Observations from Twin Cites Airport showed that many hours featured light winds less than 5 mph or calm air over the past 72 hours.

The good news is our air quality should continue to improve this week. The first in a series of bands of showers and thunderstorms is moving into the metro this morning. We can expect some “rain washed” air as the week goes on. The moisture will also be a welcome sight for many farmers and for the garden here at the Weather Lab.


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