As high pressure builds above us in the next 24 hrs, rain chances will diminish and pollution will be on the increase. Our winds have switched to the East and NE, which during the summer months, brings in transported pollution (both man-made and natural) from the eastern parts of the United States. This added pollution, which normally does not exist in our area, may cause our ozone levels to rise to over 70 ppb. by Friday and Saturday. This is a perfect example of why our current system of penalizing cities like San Antonio for high ozone is wrong. Without the additional pollution, San Antonio never reaches high ozone levels. Last summer, despite our searing heat and cloudless days, we did not go above the EPA mandated 8hr. Ozone Average Maximum of 75 ppb.. And now, the EPA may act to lower the maximum 8hr. standard even lower, forcing almost ever small, medium and large cities into non-attainment.
Below are two links to follow the potential high ozone event. On the first link, look at the sulfates in the upper right hand corner. Sulfates signify where the pollution "blob" is in the country. On the second link, just go to the ozone forecast and check out forecast where high ozone will occur. Notice that high levels will be occurring out in the Gulf of Mexico, where there are no cars. Speaking of no cars, check out the past 10 days of ozone for Joshua Tree National Park, a desolate area in south central California. They have already had several high ozone events in the past 10 days.