The United Kingdom’s new clean air strategy wants to take aim at controlling emissions of ammonia. One major source is animal manure, here being spread as fertilizer, from farming operations.

John Eveson/Minden Pictures/AP Images

United Kingdom unveils ambitious air pollution plan

The United Kingdom wants to become a global leader in cleaning up polluted air—but the island nation may not be able to meet some of its ambitious new goals by itself. Last week, the U.K. government released a draft strategy for reducing air pollution that would impose the industrialized world’s strictest emission targets for tiny particles of soot and other compounds that can lodge in peoples’ lungs and shorten their lives. The plan would also tackle a source of particulate smog that is especially hard to rein in: ammonia from farm fields and manure piles.

Air quality researchers are applauding the goals of the 104-page Clean Air Strategy, which Prime Minister Theresa May’s government released on 22 May for public comment. But achieving those goals will be a challenge, they caution, in part because much of the United Kingdom’s particulate pollution drifts in from other nations. Even at home, cleaning up multiple, widespread pollution sources will require money and political will.

The boldest goal is to halve, by 2025, the number of people breathing air with concentrations of fine particulates—particles less than 2.5 microns wide—that exceed levels set by the World Health Organization (WHO). WHO’s particulate standard of 10 micrograms per cubic meter (µg/m3), averaged over a year, is much tighter than the European Union’s limit, which is set to drop to 20 µg/m3 in 2020. (The U.S. standard is 12 µg/m3.)

That commitment is welcome, says Alastair Lewis, an atmospheric chemist at the University of York in the United Kingdom and deputy director of the National Centre for Atmospheric Science in Leeds, U.K. Although it stops short of requiring the United Kingdom to meet the stringent WHO limit in every community in the nation, it will likely “become the de facto standard that people will hold [the government] to. You can’t put the genie back in the bottle and pretend you never said it.”

To achieve the goal, the government proposes tackling emissions produced by domestic stoves and fireplaces, which account for 38% of the United Kingdom’s particulate pollution. New rules could limit the use of polluting fuels such as wet wood, for example, and raise emission standards for new stoves. The plan also envisions phasing out diesel-fueled trains by 2040 and tightening standards on vehicle tires and brakes, which throw off tiny particles during use. (The plan does not address other vehicle emissions, which a second document will cover.)

Another key strategy is to reduce emissions of ammonia, which fuels chemical reactions in the atmosphere that produce an array of problematic particulates. Farm use of fertilizers and manure from livestock and poultry produce about 88% of the United Kingdom’s ammonia emissions, so proposed plans would curb fertilizer use and require covering manure heaps to trap ammonia gas. Such steps could mark “a key turning point” for controlling ammonia emissions, says environmental physicist Mark Sutton of the Centre for Ecology & Hydrology in Edinburgh. If current trends continue, Sutton notes, the United Kingdom will fall short of meeting ammonia goals set for 2020.

But enforcing ammonia limits on thousands of farms will be complicated and could meet with resistance from agriculture interests. And although the government says it is demonstrating a commitment to go “further and faster than the EU” in combatting particulates, the United Kingdom will likely need help from other European nations to realize cuts, given that up to one-third of the nation’s smog—especially in the southeastern part of the country—drifts in from the continent in the form of precursor gases.

The sweeping plan isn’t scheduled to be finalized until early 2019, and many of the details have yet to be hashed out. “They’re fighting on an awful lot of fronts here … a huge, wide range of sectors and industries,” Lewis says. “The question is: Have they really set out a case that they will have the resources and the capacity to do that?”