Look here for:

  General information about radon
  Radon certification programs and industry associations
  Radon calibration service and chambers
  Radon measurement equipment manufacturers
  Radon mitigation equipment suppliers
  Radon zone maps

  General information about radon

EPA Indoor air Quality publications
http://www.epa.gov/iaq/radon/pubs/index.html

Midwest Universities Radon Consortium
http://www.cce.umn.edu/series/radon/

  Radon certification programs and industry associations

National Environmental Health Association – Radon Certification Program
http://www.radongas.org

National Radon Safety Board – another Radon Certification Program
http://www.nrsb.org

Council of Radiation Control Program Directors
http://www.crcpd.org/

American Association of Radon Scientists and Technologists
http://www.aarst.com

  Radon calibration service and chambers

Bowser-Morner
http://www.bowser-morner.com/

  Radon measurement equipment manufacturers

AccuStar Labs
http://www.accustarlabs.com/

Air Chek
http://www.airchek.com/

Alpha Energy Laboratories
http://www.drhomeair.com/

Diversified Research
http://alphamonitor.com/

Durridge Company
http://www.durridge.com/

F and J Specialty Products
http://www.fjspecialty.com/

Femto-Tech, Inc.
http://www.femto-tech.com/

Genitron Equipment
http://www.genitron.de/

Landauer
http://www.landauerinc.com/

NITON
http://www.niton.com/

Pylon
http://www.pylonelectronics.com/

Rad Elec
http://www.radelec.com/

RTCA
http://rtca.com/

Sun Nuclear
http://www.sunnuclear.com

Wm B. Johnson and Associates
http://johnsonnuclear.com

  Radon mitigation equipment suppliers

Festa Radon Technologies
http://www.festaradontech.com/

Professional Discount supply
http://www.radonpds.com/

Radon Supplies NA
http://www.radonsupplies.com/

Radon Control Inc.
http://www.radoncontrol.com/

Infiltec
http://www.infiltec.com

Radonaway
http://www.radonaway.com/

  Radon zone maps

EPA zone map
http://www.epa.gov/iaq/radon/zonemap.html

Kansas zone map
http://www.epa.gov/iaq/radon/zonemap/kansas.htm