U.K. firm claims tire-wear particles pose air-quality threat

STOKENCHURCH, England — A British emissions testing firm has declared pollution from tire wear can be significantly worse that tailpipe emissions, but its testing methods and findings are being questioned by the European Tire & Rubber Manufactuers Association (ETRMA).

Stockenchurch-based Emissions Analytics Ltd., an independent testing firm specializing in measuring real-world emissions and fuel efficiency, said "non-exhaust emissions" — tire-wear particles, brake wear, road debris, etc. — can be up to 1,000 times worse than emissions from exhaust, the impact of which has been diminished due to tighter emissions controls and the switch to hybrid and electric vehicles.

"Our initial tests reveal there can be a shocking amount of particle pollution from tires," Senior Researcher Richard Lofthouse at Emissions Analytics said, noting that non-exhaust emissions are not regulated.

"It's time to consider not just what comes out of a car's exhaust pipe but particle pollution from tire and brake wear."

The problem, Emissions Analytics said, is compounded by the rising number of larger, heavier vehicles, such as SUVs, on the roads.

In its comments, the ETRMA noted that the tire industry — through the Tire Industry Project (TIP), which is under the umbrella of the World Business Council for Sustainable Development (WBCSD) — is supporting research into the presence and environmental impact of these particles.

The ETRMA also pointed out that its analysis of the tire-wear rate results of Emissions Analytics' driving test found that they "do not reflect normal driving conditions and go far beyond the toughest realistic driving behavior."

In addition, the ETRMA said Emissions Analystics used a fully loaded vehicle fitted with "low quality" tires and incorporated "high speeds and excessive cornering" in its testing, elements it said "underscores the unrealistic nature of the driving test and its results. ...."

Emissions Analytics said emissions commonly are measured according to their size with Particulate Matter 2.5 and Particulate Matter 10 being two commonly used thresholds. PM2.5 is described by the U.S. Environmental Protection Agency as "fine inhalable particles" that are 2.5 micrometers or smaller. while PM10 are "inhalable particles" generally 10 micrometers or smaller.

Examples of PM2.5 include combustion particles, organic compounds and metals, while examples of PM10 include dust, pollen and mold. By comparison, human hair is typically 50 to 70 micrometers and fine beach sand is 90 micrometers, the EPA said.

A report released in 2019 from the U.K. Department for Environment, Food and Rural Affairs calls for increased attention to non-exhaust emissions and to quantify their impact.

The U.K. report indicates that tire particulate reduction "can be achieved primarily through reformulation and redesign. Literature does not suggest interest in enclosing the wheel to enable direct capture" of source particulates. There also is talk of filtering airflow around tires to help with capture.

Tire, brake and road surface wear account for 60% of the PM2.5 and 73% of the PM10 emissions from road transportation in the U.K., the report states. That translates into 7.4% of all primary 2.5PM emissions in the U.K. and 8.5% of all PM10 emissions.

Emissions Analytics CEO Nick Molden said, "The challenge to the industry and regulators is an almost complete black hole of consumer information, undone by frankly out-of-date regulations still preoccupied with exhaust emissions.

In the short term, he added, fitting "higher quality" tires and having tire inflated properly are ways to reduce non-exhaust emissions.

The study noted the rise in popularity of electric vehicles will add to the problem, because the weight of those vehicles will lead to more rapid tire wear.

"Ultimately, though, the car industry may have to find ways to reduce vehicle weight too," Mr. Molden said. "What is without doubt on the horizon is much-needed regulation to combat this problem. Whether that leads to specific types of low emission, harder wearing tyres is not for us to say — but change has to come."

The CEOs of 11 leading tire companies agreed at a TIP meeting in November 2019 to continue funding research into the impact of tire and road wear particles (TRWP) on the environment.

Research into TRWP over the next two years will include numerous projects studying the issue, TIP said, including extended sampling of TRWP presence in different environmental compartments (air, rivers, soil, estuaries), analyzing the degradation of TRWP, modelling TRWP fate in the environment and investigating the potential health impacts on organisms from long-term exposure to TRWP.