An extremely rare Code Maroon was spotted in Decatur, Ill., at noon. This is the worst level on the scale and is considered dangerous. Chippewa, Ohio also reported Code Maroon conditions this afternoon. Other locations in southeastern Michigan and southern Ontario reached Code Maroon briefly, too, but have since seen an improvement in air quality.
Cities that saw Code Purple air quality on Wednesday, very unhealthy with an increased health risk to the general public, included Chicago, Detroit, Cleveland, Pittsburgh, Milwaukee, Indianapolis and Cedar Rapids, Iowa. Air quality alerts related on wildfire smoke was in effect for areas of 20 states, covering nearly a third of the US population.
The alerts stretch from Iowa and Minnesota in the west to Massachusetts, Maryland, Delaware and North Carolina in the east. The New York area is being added to the list, with an alert taking effect at midnight Wednesday night. “Unhealthy air will continue today due to wildfires in Canada,” National Weather Service in Indianapolis he tweeted. “Limit outdoor activity and avoid outdoor physical activities, especially those that are sensitive to smoke.”
This round of smoke from the Canadian wildfire is perhaps a touch less intense than the one that swept through the Northeast in early June. Code Purple conditions Tuesday in and around Milwaukee had a similar air quality index (AQI) of 246 compared to New York at the height of the last episode on June 7, when Queens reached 254.
So far, the daily rate near Milwaukee is the highest in the United States of this lot. On June 7, Freemansburg in eastern Pennsylvania reached an AQI of 309 for the peak of this event. Purple code additions were presented for a daily average Wednesday, and several locations have exceeded AQI 301 in hourly observations, including an AQI of 311 in eastern Ohio.
AQI is done problematic for sensitive groups in Code Orange. With Code Red, an AQI of 151 or above, the air may be unhealthy for everyone. Code Purple starts with an AQI of 201. Code Maroon indicators of hazardous air quality start at 301.
Primary pollutants from remote fires are of the PM 2.5 variety, or fine carbon-based particles 2.5 microns in diameter and smaller. In Code Red or worse, the best protection is to stay indoors with the windows closed and go out only as necessary while wearing an N95 mask.
Where is the smoke and where is it going?
A cold front that passes through the northeast during the summer brings at least a brief respite from the heat and humidity. This year, however, it is often a harbinger of smoke. The low pressure area that gives off smoke along the path drifts close to land in the middle of the Atlantic. At the same time, a resurgence of high pressure across Quebec and Ontario will help keep smoke on its current path.
Smoke was thickest around the lower Great Lakes region and Ohio Valley Wednesday afternoon, and that section will continue to drift east and southeast through Thursday. Amid widespread Code Red conditions, Code Purple patches will also be maintained.
Fires also hit the Appalachian Mountains, with air quality dropping across Pennsylvania, Maryland and Virginia, including coastal areas, by evening. Air quality in the mid-Atlantic and urban Northeast, as well as New York state, will deteriorate further on Thursday.
The bad air is poised to remain over much of the same area ahead, though it will dip south slowly over the Great Lakes and Midwest, tapering off somewhat with the weather. Code red conditions are forecast from Ohio to the Mid-Atlantic coast on Friday, including Washington, D.C., Baltimore and Columbus, Ohio. A Code Red is also forecast from northern and western New York through Pennsylvania and into Virginia.
Tuesday counts across the country
Tuesday was a widespread Red Red day across much of the Upper Midwest, Ohio Valley, Great Lakes and Ontario. The Milwaukee area reached Code Purple. According to data from the Environmental Protection Agency, many locations saw record pollution for smoke particles in data dating back to the 1990s.
For example, the Milwaukee area recorded a 24-hour AQI, the all-day average, of 245, or the first Code Purple daily count. It surpassed the old particulate pollution record of 165 in May 2001. The Grand Rapids, Michigan area had a daily AQI of 202, surpassing the old record of 141 in March 2003. The Davenport, Iowa area had a daily AQI of 185, a record that exceeded 155 in July 2008 and 2020.
The Detroit area hit a daily AQI of 184, the second-highest on record, up from 190 in December 2006. Indianapolis had an AQI of 182, the second-highest on record, up from 191 in July 2014. That's the highest ever not related to fireworks. Dayton, Ohio recorded an AQI of 172, surpassing 159 in December 2013.
More air quality records across the United States will likely be tested or broken on Wednesday. The zones most at risk extend from western New York and southern Ontario back through Ohio and into the Midwest.
A look ahead at the implications
Unfortunately for Canadians dealing with the immediate effects and Americans watching the aftermath, the pattern that caused the storms looks likely to continue. With a record number acres burned this year, the record trend How many The carbon sent into the atmosphere in June will likely continue into July. Forecasting smoke more than a few days in advance is a difficult exercise.
Looking past this weekend is almost impossible outside of the general signals. We can conclude with reasonable confidence that high pressure heat domes will continue to dominate both eastern and western Canada. Between and below the dominant heat domes, at least occasional thunderstorms may bring intermittent rain to fire areas, particularly those in eastern Canada.
There is no sign of an end to well-above-normal temperatures across Canada, which has been warm for much of 2023 with accelerating warming due to climate change. A resurgence of high pressure to the east could lead to significantly warmer than normal readings in Quebec and areas around Hudson Bay through this weekend.
A storm like the one that has repeatedly brought smoke from wildfires across the Upper Midwest, Great Lakes and Northeast this year could continue. This doesn't mean more smoke episodes are a given, but it's a seasonal trend worth remembering.
