IOT pollution monitoring Pi or Arduino or Wio?

I am thinking of building a rig for pollution monitoring they have to relativly cheap about £100-£150 per node.I can cut hardware corners slightly as I already have 2 Uno's and 2 PI B+'s and wio node

I cant decide on the base rig, Im thinking of using a grove shield on top of either one.

It needs to be able to push data from them back to my computer through wifi or straight to the cloud

What would people recomend for processing the data and how then could i upload it to the webpage for general public to view the results. What would could I use for that?

I would prefer the sensors cheap and accurate but that may not be an option- what would you recomend for capturing the following

carbon monoxide

nitrogen oxide(s)

sulphur dioxide; ozone

Location (GPS coordinates)

Temperature

Humidity

Light intensity

noise level

If there are any dev kits more tailored to my needs that would be great

These sensors are commonly available - http://playground.arduino.cc/Main/MQGasSensors
GPS modules usually communicate via a serial interface.
The DHT11 is commonly used as a temperature and humidity sensor
How about Adafruit TSL2561 Digital Luminosity/Lux/Light Sensor Breakout : ID 439 : $5.95 : Adafruit Industries, Unique & fun DIY electronics and kits for the light sensor?
SparkFun Sound Detector - SEN-12642 - SparkFun Electronics might be usable for the sound sensor but you will need to calibrate it.

The ESP8266 is a standalone microprocessor but normally comes preloaded with software to make it behave like a wireless modem so you can use that to connect to your internet and upload data.

You can connect most of these sensors to Arduino.

Regarding Pi. Raspberry pi has a Linux OS, if the system's got disconnected from power several time, there is a chance of corrupting the OS and need to install OS and your software again.

I had a system that controls the Aeroponic system at my home controlled by Raspberry pi, recently I switched to Arduino Nano. Where I live power cuts are pretty common and thus might corrupt the pi.

+1 for sarouje's comment.
The Pi is not a install and forget system. It can become corrupted or fill up its file system with log files for example.