For single station:
WCS GET: http://webapps.datafed.net/ogc_EPA.wsfl?SERVICE=wcs&REQUEST=GetCoverage&VERSION=1.0.0
&CRS=EPSG:4326&COVERAGE=AIRNOW.pmfine&FORMAT=dataset-schema&loc_code=090050005
&TIME=2006-11-07T00:00:00Z/2006-11-07T23:00:00Z&WIDTH=-1&HEIGHT=-1&DEPTH=-1

SOS GET: http://ww1.geoenterpriselab.com/swe/sos?Service=SOS&Request=GetObservation&Offering=AIRNO
W&ObservedProperty=pmfine&procedure=090050005&&eventTime=2006-11-07T00:00:00Z/2006-11-
07T23:00:00&resultFormat=text/xml;subtype="OM/1.0.30"

SOS POST REQUEST

For bounding box:
WCS GET: http://webapps.datafed.net/ogc_EPA.wsfl?SERVICE=wcs&REQUEST=GetCoverage&VERSION=1.0.
0&CRS=EPSG:4326&COVERAGE=AIRNOW.pmfine&FORMAT=dataset-schema&BBOX=-
75.23444,39.58,-72.65889,41.98,0,0&TIME=2006-11-07T08:00:00Z&WIDTH=-1&HEIGHT=-1&DEPTH=-1

SOS GET: http://ww1.geoenterpriselab.com/swe/sos?Service=SOS&Request=GetObservation&Offering=AIRNO
W&ObservedProperty=pmfine&featureOfInterest=BBOX&BBOX=-75.23444,39.58,-
72.65889,41.98&crs=EPSG:4326&eventTime=2006-11-
07T08:00:00Z&resultFormat=text/xml;subtype="OM/1.0.30"

SOS POST REQUEST

SOS Client (type in a city and select a date for which DataFed has data at least one day prior to the current date)