Air Quality Management and Urban Sustainability Notes

The Dual Nature of Urban Environments

Cities function as society’s predominant engine of innovation and wealth creation.
Paradoxically, they are also the primary sources of crime, pollution, and disease.

Drivers of Urban Crime, Disease, and Pollution

Reasons for High Urban Crime Rates:
- Population density: High concentrations of people and potential targets in small areas increase opportunities for theft and violence.
- Poverty and unemployment: Economic hardship and limited job availability drive some individuals toward property and survival crimes.
- Inequality and segregation: Sharp wealth gaps and isolated neighborhoods increase social tensions and offending.
- Anonymity and weak social ties: High numbers of strangers and lower community recognition result in reduced social control and lower deterrence.
- Concentrated illicit markets: Large cities host networks for drugs, stolen goods, and gangs that sustain violent and property crime.
- Policing strain and reporting bias: Resource limits and uneven enforcement, combined with higher reporting rates in cities, amplify recorded crime rates.
Reasons for High Urban Disease Prevalence:
- Population density: Close quarters raise contact rates and transmission opportunities for pathogens.
- Global connectivity: International airports and mass transit networks spread pathogens rapidly within and between cities.
- Overcrowding and poor housing: Informal settlements and high-occupancy housing limit physical distancing and increase exposure.
- Sanitation and water gaps: Inadequate sanitation and unsafe water supplies sustain enteric and vector-borne diseases.
- Environmental risks: Air pollution and urban heat islands worsen respiratory conditions and vector-borne disease spread.
- Surveillance and reporting patterns: Denser health systems and higher testing rates can make cities appear to be the main source of disease even when transmission exists elsewhere.
Reasons for High Urban Pollution:
- Population density: Concentrated activities raise per-area emissions from transport, heating, and waste.
- Transport concentration: Dense road networks, freight hubs, and high vehicle use generate high levels of nitrogen oxides ( $NO_x$ ) and particulate matter ( $PM$ ).
- Industrial and energy demand: Factories, power plants, and high energy use emit $CO_2$ , $SO_2$ , and particulates.
- Waste and wastewater loads: Concentrated solid/liquid waste produce methane, leachates, and local contamination.
- Reduced green space and heat islands: Lack of vegetation and higher temperatures worsen ozone ( $O_3$ ) formation and pollutant retention.
- Connectivity and construction: Airports, ports, and continual building activity spread pollutants regionally and create dust.

Case Study: Shenzhen, China

History and Growth:
- Located in southern Guangdong, bordering Hong Kong.
- Transitioned from a village of $30,000$ people in 1980 to a metropolis of over $18$ million today.
- It is the third most populous city in China, after Shanghai and Beijing.
Economic Significance:
- Known as China’s "Silicon Valley"; home to high-tech giants including Huawei, Tencent, ZTE, and DJI.
- China’s richest city and the biggest electronics manufacturing and export hub.
- The Port of Shenzhen is the world’s 4th busiest container port.
Green Initiatives:
- Green Office Building: An eight-story building with one-third of its walls open to the air, using natural design to stay cool without air conditioning.
- Low Carbon Park: A campus where mist is sprayed into the air to cool streets and remove dust.
- Policy Focus: Rethinking cities to clean smoggy air and meet energy targets.

Global Air Quality and Environmental Impacts

Tehran, Iran (2016):
- Pollution led to the death of $412$ citizens in a 23-day period.
- Concentration of ultra-fine airborne particles ( $PM_{2.5}$ ) reached over $150$ .
- $PM_{2.5}$ (less than $2.5\,micrometres$ in diameter) can penetrate lungs and enter the bloodstream, linked to chronic bronchitis, lung cancer, and heart disease.
Mumbai, India:
- Despite being a wind-swept coastal city, $25,000$ deaths were attributable to air pollution in 2020.
Maui (Lahaina) Wildfire, August 2023:
- $80\%$ of the historic town of Lahaina was destroyed.
Los Angeles Fires, 2025:
- Driven by climate "whiplash" (swings between extreme dry and wet periods) and decades-long droughts.
- Creating "tinder-dry vegetation" ready to burn.
- Governor Newsom noted that fire season has become a "fire year."

Urban Design and Public Health Frameworks

The Pathway from Policy to Health:
- Policies/Design: Density, land use diversity, connectivity, and green space.
- Behavioral Changes: Choice of transport (Walking, Cycling, Car, Public transport).
- Environmental Pathways: Air pollution, noise, temperature ( $Heat$ ), physical activity, and social contacts.
- Health Outcomes: Cardiovascular disease, obesity, blood pressure, mental health, and premature mortality.
Barcelona Case Study:
- Catalan architect Ildefons Cerdà proposed uniting the old walled city with surrounding villages using revolutionary "urban planning."
- Focused on fresh air, green spaces, and transport proximity.
- Impact of poor planning in Barcelona (Premature deaths per year):
  - Physical activity deficiency: $1154$ deaths.
  - Air pollution: $659$ deaths.
  - Noise: $599$ deaths.
  - Heat: $376$ deaths.
  - Lack of green spaces: $116$ deaths.
  - Total: $2904$ premature deaths (nearly $20\%$ of mortality).

Systemic Health Impacts of the Urban Environment

Respiratory: Lung cancer, asthma, respiratory diseases.
Head: Stroke, cerebrovascular diseases, mental health, neurodegenerative diseases, autism, cognitive impairment.
Heart/Arteries: Myocardial infarction, arrhythmia, hypertension.
Reproductive: Low birth weight, preterm birth, lower sperm quality.
General: Obesity, diabetes, thrombosis, systemic inflammation, sleep disturbance.

Local Strategy: Southampton Green City Plan

Objectives:
- Strengthen Community Engagement Officer schemes.
- Support specific species (bats, hedgehogs, peregrines).
- Implement city flood alleviation and coastal erosion schemes.
Success Measures:
- Improvement in biodiversity index.
- Increased tree canopy coverage and managed habitats.
- Sustainable drainage systems ( $SuDS$ ) in all new major developments.
Infrastructure Example:
- Millbrook Roundabout Living Wall: The first of its kind on the UK major road network; ten green columns supporting the flyover to create a cleaner environment.

Long-term Strategic Responses

Build resilient and sustainable infrastructure.
Reinvent urban environments to enhance liveability and sustainable lifestyles.
Find efficient ways to feed and fuel cities.
Meet the economic challenges of this transition.
Encourage leadership, cooperation, and lifelong learning.

Transportation and Emissions Trends

University of Southampton (UoS) Data:
- "Conferences" are the greatest contributor to university travel $CO_2$ emissions ( $~50\%$ of total $kgCO_2$ ).
- Faculty Air Travel $CO_2$ (Tonnes) per Staff & PGR FTE is highest in FEPS (Engineering and Physical Sciences).
Vehicle Predictions (Bloomberg):
- ICE (Internal Combustion Engine) fleet expected to shrink from $2025$ onwards.
- EV (Electric Vehicle) fleet predicted to reach $19\%$ of total cars by $2040$ .
Travel Mode Changes (UoS Staff % 2013 vs 2022):
- Car driver (solo): Increased from $33.30\%$ to $43.38\%$ .
- Walk: Decreased from $21.17\%$ to $17.52\%$ .
Travel Mode Changes (UoS Students % 2013 vs 2022):
- Walk: Increased from $36.40\%$ to $43.02\%$ .
- Cycle: Massive decrease from $27.30\%$ to $8.38\%$ .
- Uni-link Bus: Increased from $23.83\%$ to $34.64\%$ .

The Case for Active Transport (Cycling)

Efficiency:
- Bicycles run on "fat" and save money; cars run on "money" and make you "fat."
- $50\%$ of car trips are less than $5\,km$ .
7 Ways Bicycles Improve Cities:
1. Less risk of premature mortality (decreases risk by $10\%$ ).
2. Combines transport with exercise (cyclists weigh $2\,kg$ less on average).
3. Reduced air pollution ( $40\%$ shift in Barcelona could avoid $28$ deaths/year).
4. Less noise pollution (up to $10\,decibels$ reduction on car-free days).
5. Zero emissions ( $40\%$ shift in Barcelona reduces $200,000$ tons of $CO_2$ annually).
6. Space efficiency (one car occupies the same parking space as $10$ bicycles).
7. Happiness (active transport is associated with better mental well-being).
Transport Energy Efficiency (Megajoules per passenger km):
- Cycling: $0.06$
- Walking: $0.16$
- Tram/Light rail: $0.92$
- Bus: $0.91$
- Car: $2.10$
- Taxis: $2.94$

Global Policy and Ethics

Political Quotes: Margaret Thatcher (1989) stated that global warming is "real enough for us to make changes and sacrifices, so that we do not live at the expense of future generations."
United Nations Sustainable Development Goals (SDGs): Goal 11 (Sustainable Cities and Communities) is central to urban air quality management.

Key Questions for Consideration

Is it acceptable to travel for study/work/holiday by ship or plane?
Is it acceptable to commute by car?
Is it acceptable to buy food transported by air/ship/lorry?
Should we strictly use locally sourced, in-season food?
Should politicians always be evidence-based?
If the public votes for parties that take no action on air pollution, is this ethically sound?
How do we maintain economic development while improving air quality?
How much money would you pay per week to enjoy fresh clean air?