Urban air quality remains one of the most pressing environmental and public health challenges facing cities across Europe and beyond. While progress has been made in recent years, many urban areas still struggle to meet long-term air quality targets, particularly as climate change, urban density, and mobility demands continue to intensify.
During a recent SIERA Impact Webinar, environmental engineering experts from the SIERA Alliance explored how cities can tackle air pollution while simultaneously advancing climate goals. The session, led by Andrew Rasmussen, Project Engineer at seecon Ingenieure GmbH – part of SIERA, focused on integrated, data-driven strategies that connect mobility, urban planning, and energy systems to deliver measurable environmental impact.
The webinar made one point clear: clean air and climate protection are not competing objectives. When addressed together through coordinated planning and engineering expertise, they reinforce each other, and create healthier, more resilient cities.
Why Clean Air Has Become a Strategic Climate Priority
Air pollution is no longer viewed solely as a local environmental issue. Nitrogen dioxide (NO₂) and particulate matter (PM₂.₅ and PM₁₀) are closely linked to climate-relevant sectors such as transport, heating, and land use. As cities work toward carbon neutrality, air quality has emerged as a critical performance indicator of successful climate action.
Across Europe, many cities now comply with current EU air quality limit values. However, upcoming EU targets for 2030 and the World Health Organization’s guidelines set significantly stricter thresholds. This creates a growing gap between regulatory compliance and long-term health-based objectives.
As Andrew Rasmussen emphasized during the webinar, achieving clean air at scale requires moving beyond isolated measures. Instead, cities must adopt integrated strategies that address emissions at their source while reshaping urban systems as a whole.
The Limits of Single-Sector Solutions
Historically, urban air quality measures have often focused on individual sectors—such as traffic restrictions or vehicle electrification—implemented in isolation. While these measures can produce short-term improvements, their impact is limited if other emission sources remain unaddressed.
Key challenges highlighted during the webinar include:
- Persistent traffic-related NO₂ hotspots along major urban corridors
- Rising importance of non-exhaust particulate emissions, such as brake and tire wear
- Seasonal PM peaks driven by heating systems in winter
- Urban street canyon effects that trap pollutants at street level
Electrification, for example, significantly reduces exhaust emissions but does not eliminate particulate matter from road abrasion or braking. Similarly, traffic flow improvements alone cannot compensate for dense urban layouts that restrict air circulation.
These challenges underscore the need for coordinated planning across mobility, building energy, and urban design.
Integrated Urban Planning as the Foundation for Clean Air
One of the central messages of the webinar was the importance of integrated urban planning. Clean air objectives must be embedded into mobility concepts, heat planning, and land-use strategies from the outset—not added as an afterthought.
Andrew Rasmussen outlined several principles that define effective integrated approaches:
- Align mobility, heating, and spatial planning
Coordinated planning reduces conflicting measures and maximizes overall impact. - Reduce vehicle kilometers traveled, not just emissions per vehicle
Traffic reduction remains one of the fastest ways to lower NO₂ concentrations. - Design streets for people, not only for cars
Open Street layouts, green corridors, and reduced stop-and-go traffic improve dispersion and reduce exposure. - Using data as a decision-making backbone
Air quality monitoring and modeling help cities target measures where they deliver the greatest benefit.
By combining these elements, cities can move from reactive air quality management toward proactive, climate-aligned urban transformation.
Key Technical Levers for Cleaner Urban Air
The webinar highlighted several technical levers that consistently deliver positive outcomes when applied as part of an integrated strategy:
- Urban Green Infrastructure
Trees, green corridors, and vegetated surfaces contribute to particulate matter reduction while also mitigating heat stress. In dense urban areas, green infrastructure supports both air quality and climate adaptation.
- Traffic Reduction and Modal Shift
Low-traffic neighborhoods, improved public transport, and active mobility reduce overall emissions and improve quality of life. These measures are particularly effective in reducing NO₂ concentrations in a short timeframe.
- Smart Street Design
Urban design minimizes braking, improves traffic flow, and reduces dust resuspension can significantly lower particulate pollution—especially where non-exhaust emissions dominate.
- Electrification as Part of a Broader System
Electrification plays an essential role in eliminating exhaust emissions, but it must be combined with traffic reduction and spatial planning to address remaining pollution sources.
Together, these levers demonstrate that clean air strategies are most effective when viewed as part of a broader environmental engineering system.
Regulatory Pressure Is Increasing—but So Are Opportunities
The tightening of EU air quality standards and alignment with WHO guidelines will place additional pressure on cities in the coming years. However, the webinar also emphasized that these regulatory developments create opportunities.
Cities that invest early in integrated clean air strategies benefit from:
- Improved public health outcomes
- Greater climate resilience
- Enhanced urban livability
- Stronger alignment with ESG and sustainability frameworks
Clean air initiatives increasingly serve as visible proof points for successful climate governance and sustainable urban development.
The Role of the SIERA Alliance
Addressing complex urban challenges requires expertise across multiple disciplines. This is where the SIERA Alliance plays a critical role.
SIERA brings together 14 environmental engineering and consulting companies into an integrated ecosystem covering urban sustainability, climate strategy, infrastructure, water, digital tools, and environmental protection. By combining technical depth with strategic perspective, SIERA enables cities and organizations to translate ambitious environmental goals into implementable solutions.
Within the Alliance, seecon Ingenieure GmbH – a member of the SIERA Alliance contributes extensive expertise in environmental and urban planning, supporting municipalities with data-driven strategies for clean air, mobility, and climate action.
About the SIERA Impact Webinar Series
The SIERA Impact Webinar Series provides a platform where experts from across the SIERA Alliance share practical insights into environmental engineering challenges—from clean air and climate resilience to infrastructure transformation and ESG compliance.
Each webinar is designed to bridge the gap between regulation, strategy, and real-world implementation. Rather than focusing on theory alone, the series highlights engineering-based approaches that deliver measurable impact in complex urban and environmental systems.
Join the Conversation: SIERA Impact Webinars & seecon
How can your city or organization turn clean air ambitions into effective climate action? How can integrated planning unlock healthier, more resilient urban environments?
- Explore upcoming SIERA Impact Webinars to gain expert insights from across the SIERA Alliance.
- Connect with seecon Ingenieure GmbH – part of SIERA to learn how environmental and urban planning expertise can support your clean air and climate strategies.
- Visit SIERA to discover how integrated environmental engineering delivers real-world impact—Engineering for a Better Tomorrow.
Clean air is not just an environmental objective. It is a cornerstone of climate-resilient, future-ready cities—and it starts with integrated thinking.
