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Indoor Air Quality

Indoor Air Quality

Good indoor air quality or IAQ has long been known to be helpful to leading a healthy lifestyle. Poor IAQ on the other hand can contribute to sick building syndrome, respiratory and circulatory illnesses, cancer, poor concentration and fatigue.

According to the world health organisation (WHO), more than 80% of the urban population are exposed to air quality that exceeds WHO contaminant limits.  The WHO report further analysed PM10 and PM2.5 concentrations in 795 cities between 2008 and 2013, and found that overall global air pollution increased by 8%.

Temperature ºC

We know this to be the dominant factor in thermal comfort and the one to which we are most sensitive. Making a balance between thermal comfort, energy consumption and infection control can help optimise the healthcare environment.

Carbon Dioxide

CO2 is exhaled as a waste-product of respiration. In high concentrations it is known to contribute to tiredness and poor concentration. It is also a useful for measuring ventilation rates and as a proxy for airborne respiratory infections.

Particulate Matter (PM)

These tiny sub-micron sized dust, microorganisms, pollen particles or skin particles that float on air currents. They contribute to respiratory illness such as asthma, influenza, TB and can deposit on surfaces creating environmental reservoirs of infection.

IAQ monitors

At its core, pollution sensors can be classed into to gas sensors and optical sensors. The gas sensors are based on the reaction of the pollutant gas with an electrolyte surface to produce an electric current (electrochemical sensors) or the change in the resistive properties of a metal oxide when exposed to the gas (metal-oxide-semiconductor (MOS)). With only a few millimetres in size, gas sensors are capable of sensing CO, NO2, and O3. On the other hand, optical based sensors operate on the principle of light scattering due to fine particles, (typically used for PM10 and PM2.5) and infrared absorption (for CO2 sensing).

We are interested in using low-cost wireless sensors in hospital patient rooms to track indoor air quality over a period of time. These will measure temperature, humidity, carbon dioxide and particulate matter smaller than 10 microns. This will give us an indication of indoor environment quality and allow us to make changes that will improve both patient thermal comfort and potentially reduce risk of airborne infection.