Chemistry Reference
In-Depth Information
4 Recent Technological Developments
Emerging measurement technologies look to enable new monitoring paradigms.
An analysis of available and recent developments in air quality monitoring
technologies within the European Project “AirMonTech
1
” identified several
major areas of development:
(a) Multi-component analysis,
Most current automated measurement techniques focus on one or possibly two air
pollutants. A survey of recent developments shows major advances in multi-
component analysis. Examples include:
Online liquid chromatography systems (e.g. Marga) which sample airborne
particles into a liquid which is subsequently analysed in the field for (soluble)
particle components such as SO
4
2
,NO
3
,Cl
,Ca
2
þ
,Mg
2
þ
,K
þ
and Na
þ
[
26
].
The development of aerosol mass spectrometers (AMS), starting with work by
Allen and Gould [
27
] and Sinha et al. [
28
], which focusses mainly on compounds
ionisable at temperatures below 1,300
C such as sulphates and organic matter.
Recently Park et al. [
29
] have developed a laser-induced ionisation method also
allowing the detection of some metals and metal oxides. AMS without particle size
separation are now small enough in size and power consumption to be used in long-
term monitoring networks [
30
].
Multi-elemental analysis by non-destructive X-ray fluorescence (XRF) is possible
on filter tape samples similar to those collected for particle light absorption
measurements. Up to 23 elements with the atomic number of potassium and above
can be analysed by this method simultaneously, with a time resolution down to 15 min.
(b) Small, low cost, portable devices with low power consumption,
Existing technologies are being miniaturised and new small devices are being
developed. Good examples are handheld condensation particle counters (CPCs)
(e.g. TSI 3007) measuring submicrometer particle number concentrations, hand-
held and portable devices for submicrometer particle surface area concentrations
(sometimes along with particle number concentrations) as summarised and compared
in Asbach et al. [
31
], and small personal black carbon (particle light absorption)
monitors (e.g. the microAeth
). The development of sensors based on micro-
electro-mechanical systems (MEMS) for PM mass concentrations, and electrochem-
ical and semiconductor systems for gases, which are small enough to be implemented
in smartphones also offers new and interesting possibilities (e.g. [
32
]).
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, NO
2
,CO,O
3
,benzeneandnoise,orthe
™
