This must cast doubt on some of the more alarmist claims about numbers of deaths attributable at least partly to emissions from vehicle engines, diesels in particular. It seems recent improvements in technology weren’t fully accounted for.
A team of researchers at the University of York in the U.K. has found that the proportion of nitrogen dioxide (NO2) in nitrogen oxides in European traffic emissions is smaller than has been thought, reports Phy.org.
In their paper published in the journal Nature Geoscience, the group describes analyzing data from roadside monitors over the course of many years and what they found by doing so.
Drew Gentner and Fulizi Xiong with Yale University offer a News and Views perspective on the work done by the team in the same journal issue and suggest that the team’s findings could have implications for air pollution standards organizations in many more places than just Europe.
One of the types of pollutants emitted by cars and trucks is nitrogen oxides (NOx), in particular NO2 and nitric oxide (NO). These pollutants have been in the news in Europe over the past couple of decades because many truck and car owners have chosen to switch to vehicles powered by diesel fuel, which costs less than gasoline—but such vehicles also emit more NOx.
To combat air pollution, officials in Europe and the U.K have enacted emissions standards that have resulted in less NOx emitted into the atmosphere. But most such emissions have applied only to NO2, which has muddied the standards.
Making things ever murkier—such standards have been based on the percentage of NO2 in total NOx emissions. This is because not only do vehicles emit NO2 directly, but NO turns into NO2 over time once released into the air. Now, it appears that the percentages that officials have been using to set their standards have been wrong.
To get an accurate measurement of the true percentage of NO2 in the NOx being emitted by vehicles, the researchers analyzed data from roadside monitors across Europe. In looking at the data, they found that NO2 percentages had risen, as expected, during the period 1995 to 2010 (as people converted to diesel) but then as emissions regulations came into effect, the percentage of NO2 leveled off and has remained at those levels ever since. These levels, the researchers note, are roughly half of what is described by air quality policy, which suggests Europe may reach mandated levels sooner than thought.
Gentner and Fulizi Xiong suggest the group’s finding could have also implications for developing nations as well because consumers there tend to buy used diesel vehicles from Europe.
via Tallbloke’s Talkshop
November 28, 2017 at 09:33AM