Ask A Scientist© Environmental Science Archive

Author:     penn
Text:       Could you tell me the amount of ozone that is at ground level in a 
typically polluted city? Please tell me of any references that I can consult 
to elaborate on this subject.

Response #: 1 of 2
Author:     Don Libby
Text:       In Wisconsin, the state Department of Natural Resources monitors 
and reports ground-level ozone data. You might try either the corresponding 
department in your own state government, or possibly your city health 
department. As for references, you could try your library, browsing through 
"smog," "air pollution," "ozone," etc. Sorry I could not be more specific.



Response #: 2 of 2
Author:     Mark Fernau
Text:       Ground-level ozone is measured in parts per billion by volume 
(ppb). The law is that 120 ppb hourly average can only be exceeded once per 
year. A city like Mexico City gets up around 500 ppb. Los Angeles has cleaned 
up their act they are around 200 to 300 when bad and exceed 120 something like 
200 days a year. Chicago, Houston, and the Northeast cities get up around 160 
to 200 ppb. Other cities are polluted but not as bad, like 120 to 160. There 
are about 90 areas in all in the US where 120 pbb is exceeded. Ozone and the 
chemicals that make ozone are transported downwind so it is a difficult 
problem to resolve. This is a very complicated subject. EPA maintains an AIRS 
data base with ozone values for each city that has an 800 number from which 
you could order data, if you are dying to get gory details. Otherwise contact 
your city or state air qualityagency.