Metro Vancouver’s proposed $470-million, 500,000-tonne-a-year waste incinerator could pump massive amounts of potentially toxic nanoparticles into the air, worsening poor air quality and respiratory disease in the region, scientists say.
Frying garbage at high temperatures creates gigantic numbers of super-tiny smog particles that are only a few nanometres (or billionths of a metre) in size, also known as ultrafine particles. These particles are so minuscule they can penetrate deeply into the lungs and bloodstream, which makes them far more toxic than larger particles.
“I don’t think there’s any question among health professionals that the smaller the particle, the more problematic it is from a health perspective,” said Ian McKendry, an air-pollution expert and geography professor at UBC, in a phone interview from his office.
“There is a large body of credible published evidence to suggest that there is indeed sufficient cause for concern [about the incinerator plan], especially from dioxins and nano-particles,” McKendry wrote in a February report for the Fraser Valley Regional District on the proposed incinerator.
Incinerators come equipped with filters to catch emissions, but these are generally designed to capture mostly large particles, said Vyvyan Howard, a nanoparticle expert and professor of bioimaging at the University of Ulster, in a phone interview from his office in Coleraine, Northern Ireland.
The filters typically let through five to 30 percent of smaller particles under 2.5 microns (millionths of a metre) in size, which cause the worst health damage, Howard noted in a 2009 report on a proposed incinerator in Cork, Ireland.As for the smallest, nano-sized particles, today’s incinerator filters allow the majority of them to pass through and into the air, Howard wrote.
Europeans lose an average of eight months of life expectancy due to fine-particle pollution of 2.5 microns in size, which leads to the equivalent of 3.6 million life-years lost each year, according to a 2005 report by the European Commission.
Nanoparticles are even more toxic than fine particles. That’s partly because they have far more surface area that can react with body tissues than bigger particles of the same weight. (For example, a cubic metre block of wood split into 10,000 splinters will offer up far more surface area than the original block.)
A 2009 report on Metro Vancouver’s waste-management options by the firm AECOM downplayed the concerns. It said an incinerator wouldn’t produce as much pollution as other sources, like cars and cement kilns.
It said incinerator filters typically capture 99.9 percent of all particles by weight. But it conceded that the filters may not be as good at capturing ultrafine particles. “Some experimental results have shown that air pollution control devices, such as fabric filters, may be more effective for larger particles”¦than for ultrafine particles,” the report said.
Howard retorts that incinerator emissions include dioxins and metals such as mercury, which are more toxic than pollution from other sources.
He also said it’s the number, not weight, of nanoparticles getting out that poses the problem. Ultrafine particles “are generally around only one percent of the total mass [of air pollution] but present the majority of the surface area that is reactive to human tissues,” he said in his report.