What is the impact of climate and air quality policies on ozone pollution in Beijing?

Researchers are examining how various climate and air quality policies are influencing ozone levels in China’s capital.

In recent years, China's efforts to tackle air pollution have shown promising results, with significant reductions in harmful emissions across the country. As part of a broader push towards sustainability, China has also begun implementing carbon neutrality (CN) policies aimed at combating climate change. However, these policies may have a complex impact on air quality, particularly concerning the formation of ground-level ozone, a key pollutant with serious health implications.

A recent study has shed light on how different combinations of air quality and carbon neutrality policies could influence ozone production in Beijing, one of China's most populated and polluted cities. 

A team of scientists, led by researchers from the National Centre for Atmospheric Science at the University of York , used a detailed chemical computer model to predict future ozone levels in the capital city under various policy scenarios - taking into account anticipated changes in emissions of volatile organic compounds, nitrogen oxides, and particulate matter.

The role of volatile organic compounds in ozone formation

The study found that changing emissions of volatile organic compounds play a critical role in the formation of ozone. Volatile organic compounds are chemicals released as gases from different liquids or solids. 

“A small increase in volatile organic compounds could significantly boost ozone production, with our model showing that a mere 5% rise in alkenes, a highly reactive group of volatile organic compounds, could lead to a 1.12% increase in ozone production,” explains Beth Nelson , a Research Associate in Atmospheric Composition Measurements and Modelling at the National Centre for Atmospheric Science based at the University of York. 

Interestingly, the research team also highlighted that reducing less reactive but more abundant volatile organic compounds, such as short-chain alkanes, could be more effective in lowering ozone levels. This finding suggests that targeted reductions in specific volatile organic compound emissions could yield better air quality outcomes than broader, less focused approaches.

The impact of carbon neutrality policies on air pollution

Dr Beth Nelson describes the impact of several policy scenarios, each with varying degrees of ambition in reducing emissions and achieving carbon neutrality: “The Ambitious Pollution 1.5D Goals scenario, which aligns with global efforts to limit temperature rise to 1.5°C, was found to be the most effective in reducing ozone production by 2060. However, this scenario was not the most impactful in the mid-term, between 2030 and 2045. Instead, the Ambitious Pollution Neutral Goals policy, which aims for net-zero emissions by 2060, showed greater reductions in ozone production during this period.”

The study also examined the potential effects of climate change on ozone production levels, particularly the impact of increased biogenic volatile organic compound emissions - from plants - due to rising temperatures. 

The findings indicated that a doubling of these natural emissions could lead to an 18% increase in ozone production by 2060. This highlights the significant influence of climate-induced changes on air quality, and the importance of carefully considering the deployment of green infrastructure in cities.

Future implications for Beijing's air quality

This research underscores the importance of considering the complex interactions between air quality and carbon neutrality policies. While efforts to decarbonise and reduce emissions are crucial for mitigating climate change, they must be carefully managed to avoid unintended consequences - such as increased ozone pollution.

For policymakers in Beijing and beyond, this study provides valuable insights into how different strategies might influence air quality in the future. 

By focusing on specific volatile organic compound reductions and accounting for climate-related changes, it may be possible to craft policies that achieve both cleaner air and a stable climate.

As China continues its journey towards a greener future, this research serves as a reminder that the path to sustainability will feature challenges and trade-offs, requiring a nuanced approach to both air quality and climate action goals.