"100 Times More Polluting": Study Reveals Industries You Didn't Know Were Harming Your Air

Air pollution rules are far weaker in some industries than others, according to new research from the University of York. The study looked at legal limits for nitrogen oxides pollutants that come from engines, flues, and chimneys and include harmful nitrogen dioxide, which is a serious issue in many UK cities.

The researchers behind this study compared different engines, turbines, and boilers - ranging from small household boilers to large power stations, ships, and aircraft - based on how much pollution they produce per unit of energy.

Lead researcher Dr Sarah Moller told The Guardian, "We expected that larger emitters, such as power stations, would have stricter limits than smaller appliances like the gas boiler that you have in your home. But this wasn't the case. Per unit of energy produced, power stations can emit 10 times more nitrogen oxides than the gas boiler in your home, and a digger working on your road could emit 100 times more."

Sectors such as shipping, aviation, construction, and farming have some of the loosest air pollution controls, often due to weak regulations rather than a lack of technology. For example, a ship's diesel engine is allowed to emit five times more nitrogen oxides than the same engine used in a generator. A diesel generator at a construction site can emit up to 48 times more than a home boiler while producing the same energy.

Biomass plants, coal-burning facilities, and medium-sized boilers also have weaker pollution rules than fossil gas systems. Some biomass power stations, such as Drax, are legally permitted to emit more nitrogen oxides.

Many polluting engines and machines will remain in use for decades. The average age of a merchant ship is 22 years, and in 2018, over a third of UK diesel trains were built before any emission limits were introduced. The researchers said that enforcing stricter standards now would help improve air quality for many years to come.

As the UK moves towards net zero emissions, cars and homes will increasingly shift to electricity, reducing air pollution. However, other sectors plan to switch to lower-carbon fuels like biofuels, hydrogen, ammonia, and sustainable aviation fuel. These fuels still produce nitrogen oxides and can harm air quality.

Shipping is expected to double and aviation to triple by 2050. These sectors currently face the weakest pollution rules. Co-author Lucy Webster said: "As we transition to net zero, stricter pollution limits should be applied to low-carbon alternative fuels to make sure we get both cleaner air and climate benefits. This is especially important in sectors like aviation and shipping, where activity is expected to grow. If limits for alternative fuels are kept the same as for current fuels, then pollution from nitrogen oxides will likely increase."