July 27, 2009
Good to Moderate AQI in US; Alaska fires update
Today air quality in US did not change much from yesterday: moderate conditions more persistent in Southern California, Oklahoma and Southeast while the rest of the country enjoyed good conditions in great part of the day (top, left).
Ozone levels were good in most of the country: most serious episodes took place in the West Coast, comprising California, Oregon and Washington. A zoom in California is showed in the (top,right) image.
Still on ozone, a curious note: an article was posted today in the website US News stating that although the National Ambient Air Quality Standard allows a maximum ozone concentration of up to 75 ppb over an 8-hour period, tests were performed showing that a significant decrease in lung function and respiratory symptoms start to occur at ozone concentrations of 70 ppb after 5.6 hours of exposure. The study appears in the August 1 issue of the American Journal of Respiratory and Critical Care Medicine and the full article can be seen here.
And now the updates about the fires in Alaska. Today another Air Quality Advisory was issued and looks like the predictions of hazardous conditions are back: for many cities in the central part of Alaska air quality will be predominantly moderate with very unhealthy periods and in the cities closest to the fires hazardous conditions may develop at times. This latest report can be viewed here.
The bottom images show the situation in the region both from MODIS Terra (left) and NOAA's HMS map (right): despite the extensive cloud coverage we still can see the ribbon of smoke going from central Alaska to Northern Canada much similar as yesterday's image.
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