The Dispersion of Traffic Related Pollutants Across a Non-Homogeneous Street Canyon

Karra, Styliani; Malki-Epshtein, Liora; Neophytou, Marina

doi:10.1016/j.proenv.2011.03.004

Cited by 18 publications

(11 citation statements)

References 15 publications

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“…The values of and used in this paper are based on 90 percentile values based on the methods and tables in [15] [16]. In Bi-scale sampling algorithm, Equation (1) and (2) are used in the calculation of CI of the data where ̂ and are estimated from the log of experimental data.…”

Section: Statistics With Confidencementioning

confidence: 99%

Bi-scale temporal sampling strategy for traffic-induced pollution data with Wireless Sensor Networks

Shum

Hailes

Gupta

et al. 2014

39th Annual IEEE Conference on Local Computer Networks

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Carbon Monoxide (CO) induced by traffic pollution is highly dynamic and non-linear. In a pilot research, we collected some fine-grained 1Hz CO pollution data from a residential road and a busy motorway in Hyderabad, India, in preparation of the deployment of a larger scale, longer term wireless sensor monitoring system. Power conservation is an important issue as the sensor nodes are battery operated. We studied the characteristics of the collected data and designed an adaptive sampling algorithm, Bi-Scale temporal sampler, which adapts the sampling frequency to the statistics collected in real time. This design has incorporated practical engineering considerations including minimising electronic noise, sensor warm-up time and data characteristics. Results show that Bi-Scale sampler achieves better energy saving and statistical deviation ratio for our requirements than burst sampling and eSENSE sampling strategies, which are techniques popularly used in environmental monitoring applications.

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Section: Statistics With Confidencementioning

confidence: 99%

Bi-scale temporal sampling strategy for traffic-induced pollution data with Wireless Sensor Networks

Shum

Hailes

Gupta

et al. 2014

39th Annual IEEE Conference on Local Computer Networks

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“…For streetlevel traffic pollution, the majority of CO comes from the emission of vehicles. From the experience in the pilot experiments in Cyprus using ICOM devices [2], it was found that the 15-minute time averaged CO concentration peaked at around 15-18ppm. Hence, we focussed on calibrating the region of 0-20ppm.…”

Section: A Calibrating Factorsmentioning

confidence: 99%

“…The reasons for developing our own sensor module and performing first hand calibrations are three-fold: i) As a prerequisite for our collaborative project between India and the UK 2 , and for the scalability of the system, the devices are required to be lowcost, and manufacturing our own devices is the only way to minimise cost; ii) it is important to understand the conditions under which calibrations are performed, so that one can obtain an accurate assessment of the likely errors from a 1 Refer to Alphasense, http://www.alphasense.com/, City Technology http://www.citytech.com/. 2 IUATC -India-UK Advance Technology Centre, http://www.iuatc.com/ measurement campaign. The commercial sensors we must use in order for the systems to remain cheap are not well calibrated for the environments in which we deploy them; iii) commercial CO monitors usually report processed data, e.g.…”

Section: Introductionmentioning

confidence: 99%

“…-must be addressed. So, for example, pilot studies in [2] using Learian CO monitors showed that the differences in time-averaged CO concentrations at different locations in a street is very small. This has been taken to imply a stringent calibration accuracy requirement of <0.5ppm (parts-per-million), which is difficult to achieve because of baseline drifts and degradation of sensors with time and exposure to pollutants.…”

Section: Introductionmentioning

confidence: 99%

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Making sense of sensor data in practical wireless sensor network designs

Shum

Hailes

McPhillips

et al. 2012

2012 International Conference on Computing, Networking and Communications (ICNC)

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Fine-grained street-level Carbon Monoxide data with stringent accuracy requirements are required in a collaborative project with environmental scientists. In this project, the chosen electrochemical sensors and the sensor modules were calibrated against concentration and temperature, which is the major environmental factor that affects the baseline of the calibration curve. It was found that there are other environmental factors, including humidity, air flow rate and other gases particular to this application that may contribute to the inaccuracy in the measurements and should be addressed in the system design. The sensitivity of the sensors also decreases with time, which means that sensors are required to be re-calibrated during a long deployment. Observations from real experiments are reported in this paper.

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“…Richmond-Bryant and Reff (2012) illustrated the use of meteorology and building topography for predicting the spatial and temporal variation in contaminant retention within a dense matrix of urban street canyons. Karra et al (2012) measured traffic emissions at several locations along and across a non-homogeneous symmetrical street canyon in Nicosia, Cyprus, with a single off-center traffic lane. The levels of pollution experienced at ground level, depending greatly on street geometry and local wind conditions, are affected by the location of the traffic lanes, and thus might exceed safe pollution levels for long periods in time.…”

Section: Introductionmentioning

confidence: 99%

Effect of street geometrical layout on dispersion emissions of traffic exhaust: experimental simulation

Yassin¹,

Ohba²

2012

Clean Techn Environ Policy

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Pollutants dispersion emitted from road traffic is a dominant source of urban air pollution. Therefore, it is necessary to quantify emission levels in urban street canyon to evaluate their impacts on the public health and the environment. In this article, we study the effect of different street geometrical layouts on dispersion emissions of traffic exhausts for winds perpendicular to the roadway. A wind tunnel experiment modeling three different street geometrical layouts was executed to examine the flow fields and the concentration distributions in urban canyon. The flow and pollutants concentration were measured using a hotwire anemometer with a split-fiber probe and a fast flame ionization detector under neutral atmospheric conditions. Flow and Dispersion characteristics were studied that included mean velocity, turbulence intensity, Reynolds stress, turbulent kinetic energy (TKE), mean concentrations, and fluctuation intensity of concentration in the street canyon. The results show that the vertical velocity and turbulent energy increases as the aspect ratio increases. The pollutant concentration increases as the aspect ratio decreases. The concentration fluctuation intensities of the aspect ratio W/H = 1 was found lower than that of the aspect ratios W/H = and . The pollutant concentration at the leeward side of the aspect ratios W/H = and 1 was higher than that in the aspect ratios W/H = . The pollutant concentration distributions measured in the experiment indicates that the variability of the street geometrical layouts in urban environment are important parameters for estimating air quality in the urban canyon.

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The Dispersion of Traffic Related Pollutants Across a Non-Homogeneous Street Canyon

Cited by 18 publications

References 15 publications

Bi-scale temporal sampling strategy for traffic-induced pollution data with Wireless Sensor Networks

Bi-scale temporal sampling strategy for traffic-induced pollution data with Wireless Sensor Networks

Making sense of sensor data in practical wireless sensor network designs

Effect of street geometrical layout on dispersion emissions of traffic exhaust: experimental simulation

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