Prompted by these EU requirements, CEN/TC 264 Air Quality established working group CEN/TC 264/WG 15 to present a manual standard gravimetric measurement method for the determination of the PM2,5 mass concentration of suspended particulate matter in ambient air.
There are no traceable reference standards for PM2,.5 measurements. Therefore, the standard measurement method set out in EN 14907  effectively defines the measured quantity by convention, specifically by the sampling inlet design and associated operational parameters covering the whole measurement process.
To support the drafting of the standard measuring method EN 14907, working group EN/TC 264/WG 15 on PM2,5 carried out a field evaluation program at various test cations throughout the EU. Following a pilot study, 8 test locations representative of arious ambient air situations were chosen so that the impact of semi volatile particulate atter to the PM2,5 mass concentration would be investigated.
The field evaluation was focused on the following aspects:
• to select, validate and assess the practicability of the designated manual gravimetric M2,5 standard measurement method
• to determine the performance characteristics of the standard measurement method, otably measurement uncertainty
• to develop a practical test procedure to demonstrate whether non standard easurement methods (like other manual gravimetric or automatic monitoring ethods) are equivalent to the designated standard method.
• to provide information on the performance and measurement uncertainties of some ommonly deployed automatic PM2,5 measurement methods, in line with the ncertainty requirements set out in the data quality objectives within the Directive 999/30/EC.
1 Measurement methods
WG 15 agreed that the candidate reference samplers to take part in the Field Test hall comprise:
(1) the 'Mini-WRAC', at the request of the EC;
(2) a Low Volume 'unconditioned' system (with no mechanism to reduce solar eating effects on the sampling line or filter), for comparability with the PM10 tandard EN 12341 ;
(3) a High Volume system, for comparability with the PM10 standard EN 12341;
(4) a Low Volume 'conditioned' system, with an air flow mechanism designed to educe solar heating effects, because of the recent understanding of the ignificance of these effects;
(5) a US-EPA approved WINS system, for comparability with US-EPA;
(6) a Sharp Cut Cyclone (SCC) system, because of the potential practical dvantages of a cyclone inlet over an impactor inlet, provided that the SCC nlet is not commercially restricted.