July 4, 2011
Dense plume of smoke covering Southern Plains, Mississippi Valley, and Southeast states; How will federal holiday affect US air quality ?
According to NOAA's HMS, remnant smoke still lingers in northern Canada from the wildfires in Ontario, Alberta, and Saskatchewan. A denser plume of smoke from wildfires in the southwest and southeast states is covering a large section of the southern half of the US (bottom left, courtesy HMS). Due to these wildfires aforementioned, much of the southeast experienced hazy conditions as seen on the MODIS Terra-true color image below (bottom right).
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If we take a closer look, we can pinpoint fires in the Carolinas, and the smoke emanating from each (bottom left). With all this activity in the southeast, it's no surprise that PM2.5 levels today climbed to the Moderate, Unhealthy for Sensitive Groups, and Unhealthy AQI levels (bottom right).
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Since today marks a federal holiday in the US, and is directly correlated to an increase of pollutants in the atmosphere due to anthropogenic activities, it is important to consider the question: Do fireworks cause air pollution? Because wildfires can have a catastrophic affect on air quality, in previous years, cities have been known to cancel firework shows in order to minimize the risk of wildfire ignition. This year, that threat was very low, as the Storm Prediction Center's (SPC's) Fire Weather Outlook had forecast no critical areas for fire weather.
However the holiday's patriotic displays of fire can still make a less obvious impact on air quality. Officials report that it is not unusual to experience spikes in PM 2.5 levels on July 4th and 5th, especially when fireworks are used in areas where smoke is already present. For some cities, Independence Day traditions of charcoal barbeques and sparklers can cause it to exceed its pollution threshold. To help counteract fireworks-related pollution from affecting a cities air quality ranking, the EPA allows states to discount high readings in the case of "exceptional events", such as Independence Day.
It is also important to note that weather conditions play a big role in fireworks-related pollution. A powerful line of storms sweeping across the US the day after the holiday, verses calm anti-cyclonic winds around an approaching high pressure system, makes a critical impact on whether or not particles will disperse quickly or linger in a region, contributing to poor air quality conditions.
Posted by Alexandra St Pe at July 4, 2011 8:11 PM