AirThings has AirThings Wave Plus Smart Air Quality Monitor (Limited Edition Black) on sale for $139. Shipping is free.

Includes the following sensors:

• Radon
  • You can't see or smell it, but long-term exposure to this radioactive gas is the top cause of lung cancer in non-smokers.
• Carbon Dioxide (CO2)
  • When it reaches high levels indoors, carbon dioxide (CO2) can cause poor sleep and trouble concentrating.
• Temperature
  • Temperature is not just a matter of comfort, it can negatively affect sleep quality, mood, and alertness.
• Airborne chemicals (VOCs)
  • Volatile organic compounds (VOCs) are airborne chemicals emitted by everyday items – many are harmless but some are toxic.
• Air pressure
  • Changes in air pressure affect radon levels and, for some, they can trigger headaches, joint stiffness and pain.
• Humidity
  • High humidity promotes mold growth and aggravates asthma symptoms, while too-dry air can lead to skin and throat irritation.