Air quality sensors

Sometimes people enter a room and notice at once that the air inside is stuffy , while most people inside the room have been getting tired, but were unaware of the poor air quality. This is because our biological air quality sensor, the nose, gets used to slow changes of surrounding smells. 

The first air-quality sensors for cars used a Japanese sensor element in which a sensitive tin-oxide material was layered onto a ceramic carrier. This sensor matches very well the requirements for a sensor for controlling air quality in petrol-driven vehicles. In 1986 the first generation was completed it used an Sn02 sensor and detected more than 85% of exhaust gases. However, diesel engines also produce nitrogen oxides, which can not be detected by tin-oxide sensors. 

Standardization of the AQS system enables paragon to provide sensors of superior value and quality, which enables car manufacturers to supply comfortable cars with a high performance air-quality management system. As for other components, the trend is that more and more compact cars are equipped with air-quality sensors to improve safety, health, and comfort. The customer is offered an effective air-quality management, with plenty more potential for the future. 

Fig. 7.17.3 The latest generation of air quality sensors with additional, multi-functional features...

Finally, different types of VOC detectors based on semi-conductor techniques are available. Sensors of this type are commonly called air quality sensors and give an output signal scaled as 0-100% air quality. Only limited experience of the use of such devices has been presented in the literature. However, a series of tests carried out by Fahlen et al. (1992) showed that a common feature of such sensors is that they generally are highly sensitive both to temperature and humidity. 

Modern EMCS use a variety of sensors, including temperature, humidity, occupancy, light, pressure, air flow, indoor air quality, and electric power (normally pulses from power meters). The actuators are... 

Some application areas of gas sensors are described in chapter 5.3, including gas and fuel powered domestic burner control, air quality sensing, indoor detection of CO, and natural gas detection. Several further applications of gas sensors are still in the development stage, e.g. for cooking and frying control, or for controlling the self-cleaning procedure (pyrolysis) of ovens. 

In this sub-chapter we intend to give an overview of household appliances using the different gas sensor principles mentioned in the previous chapters. The appliances can be divided into two categories gas sensors for safety and for comfort. Natural gas and CO-alarm systems for example are safety-relevant whereas air quality measurement, control of self-cleaning of ovens etc. are more or less a matter of comfort or energy-saving. 

Endres, H.E. Air Quality Measurement and Management. In Sensors in Intelligent Buildings, Sensors Applications Volume 2, edited by O. Gassmann, H. Meix-ner, Wiley-VCH Weinheim (2000), p. 85-103. 

Kaneyasu, J. Otsuka, K. Setoguchi, Y. Sonoda, S. Nakahara, T. Aso, I. Naka-gaichi, N. A carbon dioxide gas sensor based on solid electrolyte for air quality control. Sensors and Actuators B, 66 (2000) 1-3, p. 56-58. 

Multi-sensor fire detectors provide faster detection with fewer false alarms. These sensors are capable of monitoring the environment for multiple purposes, e.g. carbon monoxide concentration, concentration of flammable gases and indoor air quality, too. 

A working group on odours of the Inspectorate for the Environment in The Netherlands proposed, in 1983, an air quality standard for odour concentration in dwellings around odour sources (3). Because odour concentrations always have to be assessed sensorically, a guideline for olfactometric measurement was also included in the same report. Detailed recommendations were not included. In 1985 a draft chapter on odours will be pubished in the Air Pollution Control Manual with more details and comments on the measuring methods in use in The Netherlands (4). 

The exploitation of ambient fuels is attractive in situations where power needs for small electronic devices are distributed, disconnected, and long-term. This might be true for electronic sensor systems for monitoring of plant health, air quality, weather, or the presence of biohazards. In principle, the fuel can be derived from carbohydrates contained in plants or from effluent of human or animal processes. 

Liu Y, Kahn RA, Chaloulakou A, Koutrakis P (2009) Analysis of the impact of the forest tires in August 2007 on air quality of Athens using multi-sensor aerosol remote sensing data, meteorology and surface observations. Atmos Environ 43(21) 3310-3318... 

An emerging trend towards combining different sensors and measurement technologies for urban air quality monitoring along with device miniaturisation is evident from new commercially available equipment such as ETL 200 by Casella (Italy), simultaneously measuring NO, N02, CO, 03, benzene and noise, or the... 

Resch B, Britter R, Outram C, Xiaoji R, Ratti C (2011) Standardised geo-sensor webs for integrated urban air quality monitoring. In Ekundayo EO (ed) Environmental monitoring, InTech, ISBN 978-953-307-724-6, pp 513-528... 

Imagine that NASA has given you a ton of money to develop a mass sensor for the International Space Station. It will be used for monitoring the air quality inside the station. Which type of mass sensor could you NOT use QCM, SAW, cantilever (in bending), or cantilever (resonant mode) ... 

The simplest air quality monitors are static sensors, which are left in the area being monitored for some length of time and are later analyzed in a laboratory. More commonly, automatic instruments are used that measure several air quality parameters and either retain the collected data on magnetic tape or transmit it by wireless transmission. 

As a rule of thumb, with stacks between about 15 and 100 m (50 and 350 ft) tall, this point of maximum concentration will be approximately 10 stack heights downwind. Therefore, the air-quality monitoring system should include at least one sensor at the point of expected maximum ground-level concentration. Additional sensors should be placed not less than 100 stack heights upwind (prevailing) to provide a background reading, and at least... 

Zhou J, Li P, Zhang S, Long Y, Zhou F, Huang Y, Yang P, and Bao M. Zeolite-modified microcantilever gas sensor for indoor air quality. Sens Actuator B 2003 94(3) 337-342. 

---