Diesel fumes may be wrong culprit in air quality fight

According to figures from the Ministry of the Environment and Water Resources (MEWR), Singapore is not on track to achieve its air quality targets by 2020 (“Singapore not meeting its air quality targets: Masagos”; Jan 26, online). The finger has been pointed by some at diesel fumes, which have been demonised because of developments in some European cities.

For air quality standards for Singapore, the MEWR targets are:

• Nitrogen dioxide: 40µg/m3 annual mean

• Sulphur dioxide: 15µg/m3 annual mean

• PM2.5: 12µg/m3 annual mean

• PM10: 20µg/m3 annual mean

MEWR’s annual average report for Singapore from 2011-2015 shows:

• Nitrogen dioxide: 24.2 µg/m3 annual mean

• Sulphur dioxide: 12.2 µg/m3 annual mean

• PM2.5: 19.6 µg/m3 annual mean

• PM10: 30.8 µg/m3 annual mean

Despite the increase in the diesel vehicle population, nitrogen dioxide and sulphur dioxide numbers are low and exceed air quality standards. The statistics that fall outside the target are the annual PM2.5 and PM10, but these are heavily skewed when there is haze.

In Germany, where annual sales of diesel vehicles are eight times higher than Singapore’s 180,000 diesel vehicle population, the PM2.5 and PM10 for Berlin at 16µg/m3 and 24 µg/m3, respectively, are lower than Singapore’s.

The United Nations Economic Commission for Europe report on Diesel Engines Exhaust shows that, since 2000, PM figures have dropped by 15 per cent. Sulphur dioxide emissions dropped by 82 per cent since 1990, while nitrogen dioxide emissions dropped by 40 per cent between 1998 and 2010.

These reductions occurred despite an increase in the total mileage clocked by diesel vehicles. Clearly, newer diesel vehicles are helping reduce pollutant levels.

Arguably, this data is more useful than emissions tests to determine if increased diesel vehicle population correlates to increased pollutants.

According to the National Environment Agency, oil refineries contribute up to 93 per cent of sulphur dioxide emissions while diesel vehicles contribute a paltry 0.1 per cent.

Are our guns being pointed in the wrong direction?

Regardless, it is crucial for greener technology to become prevalent and I urge that resources be devoted to make hybrid and electrical vehicle technology affordable. In Europe, rebates are offered for existing diesel vehicle owners who have bought them in good faith to switch to electrical or hybrid options.

The diesel tax suggested by some is not only counterproductive, it may imply that the Government is merely generating more tax revenue. Most diesel vehicles belong to the logistics and public transport sector where fuel is a major cost component.

Increasing costs without a corresponding drop in pollutant indices means its cost-benefit ratio is questionable. A predictable consequence of this measure will be increased bus and taxi fares, as well as delivery surcharges, which the general public will eventually bear.