Analysis: Gas boilers and NOx: the hidden emitter

Spike in gas boiler use this winter could compromise the UK's ability to meet legally binding air quality targets

By Kathy Grenville

Information on this page correct as of:

Air pollution, specifically nitrogen oxides (NOx) emission from gas boilers, could spike over the course of a winter spent working from home, potentially compromising the UK’s ability to meet legally binding air quality targets, a new report finds [1].

Gas combustion in buildings, from boilers and cookers, is a major source of local pollution, accounting for approximately a fifth (21%) of total NOx emissions across Greater London [2]. Modelling predicts that boiler use will rise by 56% this winter due to the coronavirus pandemic changing work patterns [3].

New analysis from the Energy and Climate Intelligence Unit (ECIU) shows that this increase in energy use has implications for urban air quality, driving up NOx emissions by approximately 12% in towns and cities – enough to offset the last two years’ worth of progress on reducing traffic emissions.

The report does not attempt to model traffic emissions over the coming winter and notes that lighter traffic during lockdown may mean a temporary reduction in the overall NOx burden.

Nevertheless, as highlighted in the report, the increase in pollution from gas boilers provides a graphic illustration of their forgotten role in contributing to air pollution. Furthermore, urban dwellers could potentially experience high pollution levels from both home heating and traffic in the near future, if many Britons continue to work from home but those who travel to their workplaces do so by car rather than public transport.

Commenting, Dr Anna Moore,Respiratory Registrar and Spokesperson for the UK Health Alliance on Climate Change, said,

"It's commonly known that nitrogen oxide pollution from road traffic harms health, and especially lung health. There’s less awareness however of alternative sources of these harmful pollutants from within our homes. Domestic gas boilers contributesignificantly to total NOx emissions.While it is important for our health to havewarm homes over the winter, the projected rise in exposure to air pollution as more people are working from home is concerning.

"However, gas boilers are not the only way of heating housesand water – at home, Ihave an air source heat pump, which runs on electricity and is more efficient than my old gas boiler.The Heat and Buildings Strategy presents an opportunity for a win-win scenario [4]: a strong and ambitious plan from the Government, supporting the public to transition to cleaner and healthier ways of keeping warm, would improve lung health and reduce the climate impact of our homes."

The author of the analysis Jess Ralston, Analyst at the Energy and Climate Intelligence Unit (ECIU) said: “The way we heat our homes needs to change if we are to get to net zero emissions by 2050. Fossil fuel heating currently accounts for around 15% of the UK’s greenhouse emissions and 21 million properties still have gas boilers, so there’s some way to go.

“Taking a lead from the UK Climate Assembly [5], where 9 in 10 people supported a gas boiler ban, the Heat and Buildings Strategy expected this year should give an indication of how the Government is going to address both the carbon emissions and air quality impacts associated with gas heating. Opting for a clean alternative will help curb CO2 emissions but also the dangerous levels of NOx highlighted in this report.”


Notes to editors:

  1. The report, Gas boilers and NOx: the hidden emitter, is attached to this email.
  2. In 2010, gas combustion accounted for 21% of total NOx emissions in Greater London:
  3. An ECIU report (2020), Lockdown in Leaky Homes, found that an extension of social distance guidelines into the winter months would boost domestic heating demand by 56%:
  4. In November 2020, the Government is set to publish its Buildings and Heat Strategy, which is expected to give details on plans to switch British homes to clean sources of heat:
  5. The first UK-wide citizens’ assembly on climate change published its final report on how the UK can reach net zero emissions by 2050 earlier this year in September: :

Download the full report here: Gas boilers and NOx: the hidden emitter