Woot offers Refurbished Amazon Smart Air Quality Monitor - Know your air, Works with Alexa  for $44.99. Free shipping for Prime Members.

Product Description:
Amazon Smart Air Quality Monitor helps you understand your indoor air quality by measuring 5 factors that affect it. The device’s indicator light gives you an idea of current air quality, while the Alexa app provides an easy-to-read air quality score.

• Know your air – Amazon Smart Air Quality Monitor makes it easy to understand what’s in your indoor air.
• Amazon Smart Air Quality Monitor measures 5 important factors of air quality: particulate matter (PM 2.5), volatile organic compounds (VOCs), carbon monoxide (CO), humidity, and temperature.
• Stay informed –
  You'll see sensor data translated into an easy-to-understand air quality score in the Alexa app, and you can also check trends over time and get general tips on how to improve air quality. Get an indication of current air quality from the color-coded LED, and an easy-to-understand air quality score in the Alexa app anytime.
• Get notifications – Pair with an Echo device, and you can ask Alexa for your indoor air quality and be alerted when air quality drops to a poor state. Assign multiple Amazon Smart Air Quality Monitors to different rooms and you can get reports for multiple areas.
• Enable Routines - With Routines, you can link Alexa-enabled devices so that they work together. For example, if Alexa detects a change in indoor air quality score, you can enable a Routine to activate compatible devices like air purifiers, dehumidifiers and fans to improve your indoor air quality.
• Easy Set Up - 1) Plug in your Amazon Smart Air Quality Monitor. 2) Open the Alexa app, tap the devices icon and add your new device by clicking the + icon. 3) View your detailed air quality at any time in the Alexa app or just ask “Alexa, what's the indoor air quality”?