Ambient
Air Quality
Activity Log
nothing logged yet ദ്ദി◝ ⩊ ◜)
nothing logged yet ദ്ദി◝ ⩊ ◜)
The first chart titled "ambient" shows temperature, humidity, pressure, light, and noise levels (relative, not actual decibels) detected by my Pimoroni Enviro+! Although I don't think its microphone is very good...
PM for short, particulate matter is airborne particles, both solid and liquid. They include dust, pollen, soot, smoke, droplets, dirt and vary in size! PM10 measures particles with a diameter of 10 micrometers or less so naturally, PM2.5 is 2.5 micrometers or less (and is thus included in PM10 measurements which is why you may often see PM2.5 and PM10 overlapped in the charts above). These particles can cause respiratory issues when inhaled, especially smaller particles like PM2.5. I detect them using a PMS5003 sensor that attaches to the Pimoroni Enviro+. Note that PM10 must be greater than or equal to PM2.5! If PM10 is ever higher, then the space between PM2.5 and PM10 is filled with particles that are between 2.5 and 10 micrometers in diameter, called coarse particles! I like to pay a lot of attention to this in the valley, since agricultural activities can stir up a lot of dust and dirt which are coarse particles, but they also can contribute to the spread of pollen and spores, including valley fever :)
The Enviro+ measures gas with the MICS6814 analog gas sensor. This allows it to measure reducing gases (think CO), oxidizing gases (like NO2), and ammonia relatively. It changes electrical resistance as gases are absorbed. I previously didn't know gases can be measured like this, and it's really cool I think! But, I really wanted actual concentration estimates instead of relative resistance, so I converted the resistance values to parts per million (ppm) using some gas conversion formulas based off the MiCS-6814 Rev 8 datasheet. NO2 (nitrogen dioxide) is a common air pollutant from combustion (cars, stoves, etc.) that irritates the respiratory system. CO (carbon monoxide) is a colorless, odorless gas that can prevent oxygen from being delivered to the body. Ammonia (NH3) is a pungent gas used in cleaning products and fertilizers that irritates the eyes, nose, and throat.
Data is uploaded from my Pimoroni Enviro+ sensor array and my PMS5003 particulate matter sensor connected to my Raspberry Pi 5. They're stationed on a 5' bookshelf in my room! These sensors aren't necessarily accurate for safety purposes but they're good for me monitoring what's in the air around me
Gas levels are measured in Ohms in the Pimoroni Enviro+, so I have to convert them into parts per million for readability. I process the gas and particulate matter data using EWMA (exponentially weighted moving average) to filter out jitter but still be responsive!
I edited the provided Pimoroni scripts to monitor rises in PM2.5 and PM10 using EWMA baselines. If they rise way above the moving average then the script auto-logs a "spike event", which usually tells me I've been burning a candle or incense stick for too long. . . I can also log events myself like when I open my window or light my candle to see how that impacts the environment in my room! A maximum of 20 logs are kept at a time :)