24 Air Monitoring


However, in 1992, the Department of Health set up a Committee on the Medical Effects of Air Pollutants (COMEAP) which concluded that up to 24,000 deaths were still being ‘brought forward’ in the UK in 1995/1996 due to the short term effects of air pollution. At that time, no standards or regulations were proposed for BC because it was assumed that effort to reduce PM10 and PM2.5 would also reduce BC.


From a public health perspective, the PM10 approach results in effective legislation to reduce overall particulate emissions, but once this has been achieved it is logical for the focus to move to the finer particulates. These often have the most detrimental effects and it is pleasing to note that BC is becoming one of the most popular subjects for discussion in many recent meetings of air quality and public health professionals.


The problem with Black Carbon


Generally speaking gaseous pollutants are breathed in and breathed out again in short fashion. In contrast, some of the fine particulate that is breathed deep into the respiratory system tends to stay there. This problem is compounded by the fact that BC effectively acts as a vehicle to transport other harmful materials which can adsorb to its large surface area. These include PAH’s and dioxins, which are known to be carcinogenic.


The measurement of particulates to PM10 and PM2.5 is complicated by the fact that a hundred-fold reduction in particle diameter equates to a million-fold reduction in mass, assuming a specific density and spherical particle shape (see table).


Particle Diameter (microns)


10


2.5 1


0.1


Particle Weight (mass units)


524.5


8.195313 0.5245


0.000525


So the most potentially harmful particles are not adequately measured by this method. In addition, carbon concentrations vary from time to time and place to place.


The regulatory focus on PM10 and PM2.5 has resulted in highly efficient combustion processes in industry and in modern engines. However, these new developments are designed to meet the PM mass standards; not necessarily to reduce the fine particulate, for which monitoring is not currently required by legislation. As a result, BC and other fine particulate materials in urban areas have become a major concern.


CARBOTRAF – a project to reduce BC levels through traffic management


CARBOTRAF is a Seventh Framework Programme (FP7) of the European Commission. Lasting for three years, the project will


A decision support system for online prediction of emission levels will use real-time and simulated traffic and air-quality data. Based on the prediction, a low emission traffic scenario will be achieved by imposing ITS (Intelligent Transport Systems) measures such as re-routing and adjustment of traffic light sequences.


The two host cities are Glasgow, Scotland and Graz, Austria which were chosen due to their ability to manage traffic flows using ITS which will be enhanced by real-time air quality monitoring systems and a decision support system provided by IBM Inc.


The project will involve international partners from both the academic and industrial sectors. For example, Air Monitors will provide BC monitors, meteorology, mobile air quality and traffic monitoring equipment, and Envirologger (an associate company of Air Monitors) will provide real-time data collection, storage and display technology. Other partners include Imperial College London, the Austrian Institute of Technology, VITO (Belgium), ETS (Belgium), EBE Solutions (Austria) and IBM.


Aethalometers employ an optical method to only measure those fine particles which are black


study the relationship between traffic flow, BC emissions and CO2 in urban environments.


The project aims to create a method, system and tools for


adaptively influencing traffic flow in real-time to reduce CO2 and BC emissions caused by road transport in urban and inter- urban areas.


The inter-relationships between traffic states and CO2 and BC emissions will be investigated. In particular, a model linking


traffic states to emission levels will be established on the basis of existing and new simulation methods and tools.


Handheld Aethalometer Recent developments Rack-mounted Aethalometer


Encouragingly, the elephant in the room is starting to be noticed. On 14th November 2011, BBC UK Environment correspondent Richard Black published an article entitled: 'air pollution 'puts lives at risk'' in which he outlined the Environmental Audit Committee's recent report which claimed the government's failure to meet EU standards on air pollution is 'putting the health of UK residents at risk. Bad air quality costs the nation £8.5 - £20bn per year via poor health,' the report says, 'and can cut life expectancy by years.'


Following a similar theme, the Sunday Times published an article entitled 'How a Breath of Air is Toxic' on 13th November 2012 which reported that people living or travelling in Britain's cities 'could be sucking in more than 100 million tiny toxic pollutant particles with each breath, according to the government's National Physical Laboratory (NPL).'


The article went on to explain: 'The tiny particles of soot and poisonous carbon compounds come from car exhausts, brakes and tyres and are thought to contribute to about 30,000 premature deaths a year from heart and lung problems.'


Clearly, the importance of BC is starting to become accepted and it is encouraging to note that a new PhD project will commence at King's College London in 2012 to study ambient levels of Black Carbon.


Summary


Historically, air quality legislation has been largely driven by human health issues and major advances have been achieved in developed countries. However, it is clear that whilst the focus on PM10/2.5 has resulted in major reductions in total airborne particulate; to date, fine particles have been largely ignored.


Additional new monitoring standards based on BC would substantially help to address this issue and drive improvements that would both enhance human health and help in the fight against climate change. If we are to make progress on both fronts, we must recognise the elephant in the room and Black Carbon should become the new PM10.


Further information is available at www.airmonitors.co.uk


Monitoring Oxygen Content in Harsh Industrial Environments


Oxygen monitoring is mandatory in many production areas, whether as an economical way to control processes or in order to efficiently identify hazards. Be prepared with the TRANSIC100LP from SICK (Germany) to measure the oxygen concentration in moist and aggressive process gases precisely with diode laser technology. It is reliable in all operational areas and with minimal maintenance and at an attractive price.


Measuring oxygen with the TRANSIC100LP is a breeze. The meter is compact, requires little space and can be easily installed directly in-situ in many applications even in hazardous areas. The operation is easy. Once powered up, the measurement values are immediately available. Typical applications include monitoring gas production and inert gas atmospheres.


The stainless steel probe is resistant to aggressive chemicals and extreme humidity. In summary, the TRANSIC100LP is a simple, robust solution with accurate high availability. The probe consists of a compact spectrometer with tunable diode laser (TDL). The laser is tuned to a wavelength characteristic of oxygen molecules. The measurement is made by the attenuation of the laser light passing through the measuring medium.


The measured attenuation allows a very selective detection of oxygen within the sensor beam. This non-contact optical measurement technology provides an exceptionally stable and reliable measurement.


Maintenance costs are low. The semiconductor lasers have been subjected to extensive aging tests to provide an average service life of upwards to 10 years in continuous operation. This significantly reduces operating costs for oxygen measurements, since sensor changes are very rarely required.


A stainless steel mesh filter and an optional porous PTFE filter protect the optical components in the probe from dust and dirt. An intelligent measurement algorithm helps in the process to minimise pollution effects and reports required maintenance before it is needed. On-site checks and calibration of the transmitter can either be done with ambient air or, with zero or calibration gases, which are fed via an optional calibration gas. The calibration interval is 12 months.


Reader Reply Card No. 63 IET November / December 2011 www.envirotech-online.com


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