Unavoidable reality of street pollution (2)

The Director of Environment at Mepa, Martin Seychell (Monitoring Of Air Quality By Planning Authority, March 17) takes George Debono to task for not updating his information sources regarding Mepa's (Malta's) Emissions Inventory (EI). Mr Seychell himself states that the latest version was only published last month (February 15) but revised on March 16.

Mr Seychell revealed which road vehicles are to blame for most of road traffic particulate emissions; HGVs (Heavy Goods Vehicles) contribute 88.7 per cent.

While defending the credibility of the recent EI's, he fails to acknowledge that, until mid-February, past EIs were telling a totally different tale. As recently as last November, Mepa's publication Air Quality Plan for the Maltese Islands - Summary of Public Participation, the authors were still under the impression (pages 31 and 42) that HGVs contributed 32 per cent of particulates while passenger cars contributed 58 per cent.

It took me over two months to scrutinise past EI's, a lot of number crunching and a few dozen pages of dissertations sent to personnel at Mr Seychell's unit to explain where and why EIs were essentially depicting a false situation. My efforts may have not been unproductive. Until mid-February, road transport EIs were a wealth of errors with disappearing HGV emissions and invisible LGV fleets (Light Goods Vehicles). Based on these EIs, Dr Debono was quite right, as I have done, to demonstrate disbelief towards previously published data. Since Dr Debono is not a full-time scrutiniser of Malta's EIs, Mr Seychell can only claim to have been saved by the bell.

Seeing that there is a dawn in realistic emissions reporting, may I take the opportunity to help take accuracy a step further.

HGVs (actually HDVs; Heavy Duty Vehicles in EI classifications) are vehicles with a GVW of over 3500 kg. In 2006 these numbered 13,000 vehicles not 40,000.

LDVs (Light Duty Vehicles with a GVW of 3,500 kg or less) consist mostly of small commercial trucks and vans. In 2006 these numbered 30,000 vehicles not 4,500.

The current, "revised" EIs still under represents LDVs which are wrongly attributed a GVW of 2,000kg or less. LDVs are a major traffic pollutant source in urban areas.

To date, HDV fleets are over represented and LDV fleets under represented.

Licensed (on the road) passenger cars are the only ones which contribute towards traffic emissions. Mepa uses the number of "registered" cars instead, so car fleets are inflated by around 50,000 vehicles.

Metal emissions from HDVs mysteriously halved in past EIs, the "error" corrected a week ago. Metal emissions from diesel passenger cars were calculated from wrong fuel sales data but still overlooked in the revised 2006 data!

Kilometrages to calculate particulate emissions should be more realistic. As things stand, Mepa's "average" petrol car uses 4.2 L/100kms (66 mpg), diesel LDVs 1.8 L/100kms (157 mpg), and HDVs 5.6 L/100kms (50 mpg) or the fuel consumption of a small diesel family hatch back!

A review of past publications by Mepa and official government statements, (as the March 2 press conference) including those on policy choices in vehicle taxation issues, wrongly depict PM10 emissions as being predominantly caused by passenger cars. HDVs and LDVs have been systematically made invisible and unaccountable.

Mr Seychell's partially valid explanation on the constituents of PM10 (Sahara dust, sea spray) does not mention dust from the construction industry. This brings up the point of "EU Air Quality Directive advice against the location of traffic oriented monitoring stations in microenvironments like street canyons", because unusually high traffic pollutants are present as a result of high buildings in narrow streets. Street canyons have been created by past and current town "planning" (sic) fuelled by property speculation not real housing needs.