Emissions from non-road diesel vehicles in the construction sector are growing, with impacts on urban air quality and health. Is it time to regulate?
With the exception of underground mines and infrastructure construction, emissions from non-road diesel engines (covering vehicles and equipment) in Australia are unregulated, despite being the fourth largest human-made source of fine particle pollution in the NSW Greater Metropolitan Region (NSW GMR), which covers Sydney, Wollongong and Newcastle.
Monitoring and controlling emissions, especially on construction sites, would help improve worker health and safety as well as improving the construction industry’s environmental footprint at site level. This would also contribute to enhanced regional air quality.
Issues connected with outdoor air quality
The World Health Organization (WHO) emphasises that air pollution continues to be a major environmental risk to human health, especially in urban areas. Elevated levels of some common air pollutants bring an increase in acute respiratory infections and cardiovascular disease in humans and contribute to premature deaths and raised cancer risks.
Evidence of the toxicity and cancer risks related to diesel exhaust emissions comes from the International Agency for Research on Cancer, which classified diesel engine exhaust as carcinogenic to humans in 2012. The World Health Assembly estimated in 2015 that some 3.7 million deaths a year are linked to exposure to outdoor air pollution. Almost 90 per cent of these deaths occur in low and middle-income countries, with almost two out of three occurring in WHO’s South-East Asia and Western Pacific regions. About 94 per cent of the deaths are due to non-communicable diseases, notably cardiovascular problems, stroke, chronic obstructive pulmonary disease and lung cancer.
While urban air quality in Australia is generally good, Australia’s National Environment Protection (Ambient Air Quality) Measure (AAA NEPM) goals for fine particles and ozone are exceeded in some Australian cities and regions. Levels of CO, NO2, SO2and lead in urban air are generally below the national standards, and decreased or remained steady in the period from 1999 to 2008.
The impact of non-road diesel engines
One of the sources of outdoor air pollution noted above is the non-road diesel engine sector in Australia, with emissions contributing perceptibly to elevated fine particle and ozone concentrations in ambient air, especially within urban areas. In the NSW GMR non-road diesel engines produced almost exactly the same annual tonnage of particulate matter smaller than 2.5 micrometres (PM2.5) as on-road vehicles, 50 per cent of NOx and 76 per cent of PM10. This is a significant figure given the overwhelmingly large number of on-roadvehicles compared to total NSW GMR vehicles.
The contribution of non-road diesel industrial and construction vehicles to PM2.5 is not accurately known since the data from the NSW GMR is incomplete. However, heavy duty non-road diesel vehicles and equipment in the NSW GMR are estimated to have a PM2.5emission intensity six times higher than the on-roadvehicle fleet.
Projected fuel consumption by the non-road diesel sector in Australia (excluding rail locomotives and large marine engines) is expected to rise sharply over the next 15-20 years, according to the NSW Environmental Protection Authority. Despite the disproportionately high contribution of the non-road diesel sector to overall emissions, no national regulations have been issued in Australia and the pollutant load has remained largely unaddressed. The resulting load of toxic and hazardous contaminants, especially in large metropolitan cities, is significant and is likely to bring rising health costs in its wake as illustrated below.
Non-road diesel and construction activities
An intensive review of the literature and interviewing experts highlights four major issues:
- The contribution of the relatively small number of non-road vehicles and equipment to total vehicular pollution load is significant.
- Non-road vehicles and equipment are unregulated in Australia generally and especially in our metropolitan areas where urban construction projects will contribute significant emissions and where they will do the most harm.
- Data for PM is gathered but most carbon emissions from non-road vehicles are not monitored. Nitrous oxide (N20), for example, has a global warming potential of 298 compared with the benchmark CO2, but is ignored. Similarly, some nitrogen emissions from diesel exhaust are ozone precursors and ozone itself is a greenhouse gas but these gases are unmonitored, even at urban level
- Emission data available from the NSW EPA is for non-road vehicles generally, rather than focused on construction sites. There are predictions of substantial near-term growth in construction site non-road vehicle numbers, the strong inference being that diesel emissions will also rise significantly. Normal infrastructure spending associated with population growth and replacement and upgrading activities, plus the recent stimulus announced by the federal government will tend to aggravate emissions and possibly health costs, according to the graph above.
Why do we ignore emissions from construction sites?
We speculate that there are perhaps four reasons we ignore emissions from construction sites.
The first is connected with geographic scale and the feeling that localemissions from construction sites would be minor connected with global ones. However, this view contradicts the “think global, act local” dictum.
A second reason could be an assumption that measuring emissions from construction activities is not straightforward. Our literature review suggests this is the case, and that accurate and representative data are difficult to obtain using current measurement techniques.
A third factor may be that construction emissions are only one component of the overall energy demand and emission outputs over the lifespan of a building or item of infrastructure. This may be correct since the major energy draw (and emissions) from a building, for example, is during the operational stage, which might be up to 50 or 60 years. However, operational energy and its emissions are regulated at source – at power plants – leaving construction emissions untouched again.
Lastly, a fourth reason could be political and business concern for construction companies that would have to upgrade their equipment upon the introduction of emission regulations. Introducing the requirement over a period of time could be a reasonable compromise.
Lack of accurate measuring real-time systems for non-road diesel engines
Since there are no regulations or standards for non-diesel engines, there is little motivation to develop a system that could track overall emissions from a construction site and contemplate measuring the individual emissions of each sub-contractor.
Emissions from construction sites are being measured in several countries using a variety of tactics, though no published data exist for Australian construction sites. Current measurement methods mainly revolve around using pre-existing fuel and emission factors for various types of non-road diesel engines. Site-based evaluations are also carried out using portable instruments but the reliability of existing techniques are dubious given short-term monitoring efforts and the variability of the operating work cycle of plant and equipment.
A practical solution is lacking that would yield accurate and longitudinal measurement of pollution. However, an automated system using new digital technologies could provide long-term monitoring and reliable data.
Dr Samad Sepasgozar and Dr John Blair are researchers at the UNSW Faculty of Built Environment.