The research found that the combustion of natural gas in boilers for heating accounted for 72 per cent of NOx emissions within a few kilometres’ radius of the BT Tower between 2021 and 2023.
Transport
The findings highlight the success of transport interventions, such as the London Low Emission Zone and the Ultra Low Emission Zone (ULEZ), in reducing NOx emissions from vehicles.
NOx emissions from vehicles in central London are estimated to have fallen by about 73 per cent between 2016 and 2025. The prevalence of Euro 6 vehicles and electric cars has contributed to this decline.
The study, published in Environmental Science & Technology, was led by Professor James Lee, professor of atmospheric chemistry at York University.
Air quality
“Our research highlights how much NOx emissions from transport have improved, but also the task still ahead in getting combustion out of cities,” he said in a statement. “Whilst talk of switching from gas to heat pumps is mainly framed around the decarbonisation benefits, it would be a major gain for air quality too.”
Dr Sam Cliff, who carried out the research while carrying out a PhD at York, said: “Without action on gas boilers it could be hard for central London to meet the WHO [2021] guideline values for NO2, no matter how clean the vehicle fleet.”
The study pinpointed the source of pollution by analysing the ratio of NOx to CO2 which differs between traffic and boilers, using long-term air pollution flux measurements taken from the BT Tower.
Heat pumps
The researchers noted that industrial and non-domestic boilers are the main contributors in central London, which is not a highly residential area.
The team estimates a damage cost penalty of up to £600m in the UK if hydrogen combustion replaces natural gas for heating rather than technologies such as heat pumps, which are acknowledged as having cost challenges for consumers.
Commenting on the findings, Martin Lewerth, Aira Group CEO, Aira UK, said: “This research makes it clear: we need to move away from gas boilers in favour of clean heat solutions, such as heat pumps, to improve air quality.
“While schemes like the Boiler Upgrade Scheme are a step in the right direction, we need the government to act decisively and rebalance the cost of electricity relative to gas, provide implementation dates for heat pump planning permission changes and revisit the gas boiler ban to accelerate the clean energy transition.
“These changes need to be handled with care, but failure to progress only causes more harm to people’s health, environment and finances. Now is the time for change.”
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