Almost half of all deaths by air pollution from transportation are caused by diesel emissions on the road, and one in three are linked to emissions from off-road vehicles and international shipping, according to a new, global study.
The findings were among several new revelations in A Global Snapshot of the Air Pollution-Related Health Impacts of Transportation Sector Emissions in 2010 and 2015, released recently by the International Council on Clean Transport and Climate and Clean Air Coalition.
The report delves into an unprecedented level of detail and scope with respect to the nature and contribution of the global transport sector to air pollution worldwide, focusing on the health and mortality burdens of fine particulate matter (PM2.5) and ozone of a comprehensive range of transport sources.
Between 2010 and 2015, the researchers found an encouraging pattern: action at the national level in key markets is working to hold steady the contribution of transport emissions to deaths by air pollution.
More vehicles, more miles travelled, but proportion of air pollution deaths from transportation emissions remain steady
Despite a growth in vehicle vehicle ownership and vehicle distance travelled between 2010 and 2015, the global fraction of air pollution-related premature deaths by tailpipe emissions stayed nearly the same.
In fact, they dropped slightly, from 11.7 per cent of deaths by all sources of air pollution in 2010 to 11.4 per cent in 2015, even as the global population grew by 5.7 per cent.
Some countries were particularly successful in reducing the impact of transportation on air pollution and, consequently, on health.
From 2010 to 2015, total concentrations of PM.2.5, ozone and black carbon from transportation declined in all regions that implemented world-class standards for fuel quality and new vehicle emissions, including the United States and Canada, EU and the European Free Trade Association countries, and Japan.
The researchers estimate that other regions that have implemented “progressive stages” of emission controls, including Brazil, Argentina, Chile, Russia and Australia have also seen declines in concentrations of these pollutants.
These successes belie an ongoing struggle, however: in absolute numbers, deaths by transport emissions increased– from 361,000 to 385,000, because of a growth in overall deaths by air pollution.
In 2015, that translated to 7.8 million years of life lost and approximately $1 trillion (2015 US$) in health damages globally from PM2.5 and ozone concentrations from tailpipe emissions alone.
“Transportation-attributable health impacts declined in the United States, European Union, and Japan as vehicle emission standards have been implemented, but these reductions have been offset by growing impacts in China, India, and other parts of the world,” said lead author of the study and an associate professor at the George Washington University Milken Institute School of Public Health, Susan Anenberg.
“Unless the pace of transportation emission reductions is accelerated, these health impacts are likely to increase in the future as the population grows, ages, and becomes more urbanized,” she said.
The researchers expect regions with world-class standards to see even further reductions as old vehicle fleets retire, but they encourage decision makers to get the momentum going, as there’s a demonstrated time-lag between putting in place relevant policies, like new vehicle and fuel standards, and realizing their full health benefits— not least because in-use vehicle fleets and related equipment have long lifetimes.
What else needs doing to reduce health impacts of air pollution by transportation?
Specifically, the researchers had a number of recommendations for decision makers. Among them were the following:
• Expand and accelerate the global uptake of world-class standards in countries and trade blocs.
• Strengthen compliance and enforcement practices.
• Accelerate fleet turnover to remove vehicles and equipment with older technology and implement low emission zones, retrofit/replacement/scrappage programs.
• Vehicle importing countries— particularly those that allow second-hand vehicle imports— should update their regulatory framework and taxation policies to ensure they do not become a dumping ground for diesel vehicles with high tailpipe PM2.5 without diesel particulate filters and nitrogen oxides emissions.
• Make reducing emissions from the transportation sector a central element of national and local management plans aimed at reducing ambient air pollution and its burden on public health.
Findings err on the conservative side
The researchers cautioned that the report’s estimated health impacts associated with the transportation sector were likely underestimated.
Firstly, they looked only at air pollution from transportation tailpipe emissions, whereas the public health impacts of the transportation sector are much broader, encompassing noise, physical activity effects, road injuries, resuspension of road dust, release of particles from brake and tyre wear, evaporative emissions and fuel life-cycle emissions.
Secondly, even the study’s health impacts estimates are likely to be conservative, because the researchers zoomed in on the impacts of PM2.5 and ozone to the exclusion of other transportation-related pollutants, like nitrogen dioxide, which is a significant cause for concern in several major cities (see box).
Nonetheless, the findings feed important information into the mammoth process of sustainable urban design, development and management, which rely on fine balances of decisions and projected consequences across a range of sectors.
For example, reducing transportation emissions while boosting access to active forms of transport (like cycling and walking) and public transport would reap the co-benefits of promoting more physical activity and reduced greenhouse gas emissions, but, on the other hand, has potential implications for injuries and fatalities from vehicle accidents.
To close gaps like these, the researchers suggest that future work address these co-benefits, quantify the future health benefits of recently adopted policies and the health damages from expected growth in transportation activity rapidly developing parts of the world, project the impacts of growing and aging populations, urbanization, and other factors that could affect transportation-related health impacts in the context of realistic policy scenarios.
Read the full report from the International Council on Clean Transport and Climate and Clean Air Coalition: A Global Snapshot of the Air Pollution-Related Health Impacts of Transportation Sector Emissions in 2010 and 2015
Read Land use, transport, and population health: estimating the health benefits of compact cities from the Lancet series Urban design, transport, and health
Banner photo by Lingaraj GJ/CC BY 2.0