Measured+Phenomena

The Air Quality Egg will measure a number of properties of environmental phenomena that relate to air quality. Here we document the key properties and how we can measure them.

Observed Properties

 * ~ Phenomenon ||~ Relevance to air quality ||~ Can we measure it? ||
 * Atmospheric Turbulence || Cf. [|Air pollution dispersion terminology: Characterization of atmospheric turbulence] || Doubtful. Maybe using external sources. ||
 * CO ||  || Yes. ||
 * Humidity || For indoor air quality (risk of mould.) || Yes. ||
 * NH3 (ammonia) ||  || ? ||
 * NO ||  || Yes. ||
 * NO2 ||  || Yes. ||
 * NOx ||  || Yes. ||
 * O3 (ozone) ||  || Yes. ||
 * Pb ||  || ? ||
 * PM2.5 || "Fine atmospheric particles — smaller than one-thirtieth of the diameter of a human hair — were identified more than 20 years ago as the most lethal of the widely dispersed air pollutants in the United States. Linked to both heart and lung disease, they kill an estimated 50,000 Americans each year." Cf. [|Particulates: Health Effects] || Yes. ||
 * PM10 || [|Particulates: Health Effects] || Yes. ||
 * SO2 ||  || ? ||
 * Temperature || Used as a control, since sensor quality may drift with temperature. || Yes. ||
 * Wind || Used for dispersion modelling || Doubtful. Maybe using external sources; but it's often quite localised. ||

Discussion
In order to integrate the readings of multiple sensors we will need to develop a better understanding of the dispersion characteristics of the various phenomena. There is a large number of existing [|air pollution dispersion models], many of which are proprietary or rely on data we won't have access to; but some may still be suitable for us. For a general discussion on air quality dispersion terminology see [|Wikipedia: Air pollution dispersion terminology], and also [|Wikipedia: Useful conversions and formulas for air dispersion modeling].

More interesting however are simple rules-of-thumb that allow us to approximate measurements for each phenomenon. For notes on this refer to the "Understanding Measurement Tolerances" section on the Data Quality page.


 * DN**: From my experience it is useful to talk about "observed properties", because a phenomenon can be interpreted differently and is the wider, less technical term. For example, a thunderstorm could be a phenomenon that is observed, and it's properties that are measured are wind speed, wind direction, rainfall, et cetera.