air pollution
Daily Breathing and Overview
- Every day we breathe about 20,000 times.
- Presentation by Julian Aherne, School of Environment, focusing on air pollution.
- Course code: ERSC-1010H; Date: November 03, 2025.
Gaussian Plume Model
- How to determine concentration of an air pollutant at a location downwind of an emissions point (stack) and within the plume.
Mathematical Model
- The formula for concentration is given as:
C(x, y, z) = \frac{Q}{2\pi U H \sigmay \sigmaz} \exp \left( -\frac{1}{2} \frac{y}{\sigmay^2} \right) \exp \left( -\frac{1}{2} \frac{z - H}{\sigmaz^2} \right) + \exp \left( -\frac{1}{2} \frac{z + H}{\sigma_z^2} \right) - Variables:
- $C(x, y, z)$: Pollutant concentration in $g/m^3$ as a function of downwind position $(x,y,z)$.
- $Q$: Mass emission rate of pollutant in $g/s$.
- $H$: Effective stack height in meters.
- $
u$: Wind speed at ‘effective’ stack height in $m/s$. - $ auy$, $ auz$: Standard deviations in the $y$ and $z$ directions (m), indicating the spread of the pollutant.
- Mass distribution in the cross-wind dimension $(y)$ and vertical dimension $(z)$ including effects of surface reflection.
Importance of Air Quality
- 99% of the global population breathes polluted air.
- Air pollution is a transboundary issue; it knows no borders.
International Focus
- International Day of Clean Air for Blue Skies: September 7, 2025, focused on the theme "Racing for Air. Every Breath Matters."
- Air pollution is described as the biggest environmental health risk of our time.
Impact of Air Pollution
- Exacerbates climate change.
- Causes economic losses and reduces agricultural productivity.
- Exposure to air pollution can lead to:
- Stroke
- Heart disease
- Lung diseases
- Cancer, etc.
- FAQ section encourages users to download a clean air guide.
Understanding Air Pollution
Definition
- Air pollution is defined as the contamination of the atmosphere (particularly the troposphere) by gaseous, liquid, and solid wastes, primarily from anthropogenic sources, at harmful concentrations that adversely affect:
- Human health
- Environment
- Material degradation
- Visibility reduction.
Statistics on Health Impact
- Air pollution contributes to 1 in 9 deaths, with approximately 7 million deaths annually due to diseases related to air pollution.
- Example mortality rates for various diseases:
- Diabetes: 1.55 million deaths
- Transportation accidents: 1.28 million
- Tuberculosis: 1.18 million
- HIV: 0.86 million
- Breast cancer: 0.70 million
- Malaria: 0.64 million
- Prostate cancer: 0.49 million
- The sum suggests around 6.70 million deaths linked to air pollution.
Specific Impact on Diseases
- Air pollution is responsible for:
- 43% of deaths from chronic obstructive pulmonary disease (COPD)
- 24% of deaths from ischemic heart disease
- 29% of deaths from lung cancer
- 25% of deaths from stroke.
Life Expectancy
- Reduction in life expectancy due to air pollution is profound:
- Paris: 6 months decrease
- Northern India: 10 years decrease.
Case Study: Ella Kissi-Debrah
- Notable case in the UK where air pollution was directly listed as the cause of death for Ella Kissi-Debrah, highlighting the severe implications of air quality.
Measuring Air Pollution
Why Care About Air Pollution?
- Understanding the impacts and methods of measuring air pollution is crucial for effective management and mitigation strategies.
Definitions and Measurement Techniques
- Fine particles (PM2.5) can significantly penetrate the lower respiratory tract.
- Human hair: 50-70 μm in diameter
- PM2.5: Particles < 2.5 μm in diameter consisting of combustion particles and organic compounds.
- PM10: Particles < 10 μm in diameter including dust and pollen.
Types of Pollutants
- Primary pollutants: Formed and emitted directly from sources.
- Secondary pollutants: Formed through chemical reactions in the atmosphere.
Monitoring Air Quality
Monitoring Networks
- Governments and researchers rely on established networks to monitor concentrations of gases and particles, including wet deposition of pollutants.
- Examples of monitoring networks include:
- AEROCAN
- Brewer/Ozonsonde
- CAPMON
- CORALNet
- GAPS
- IADN
- NAPS
- Multiple sites in Canada.
Techniques Employed
- Active sampling: Requires power (e.g., to pump air).
- Continuous sampling: Provides continuous monitoring data.
- Passive sampling: No power required for air collection; relies on diffusion or deposition.
Measurement of Wet Deposition
- Wet deposition includes bulk, wet-only, and snow precipitation chemistry monitored through networks like the Canadian Air and Precipitation Monitoring Network (CAPMON).
Gold Standard Monitoring
- Ambient concentration measurement of gases and particles considered as the 'gold standard' for air quality assessment.
Challenges in Monitoring
- Despite the effectiveness of continuous samplers, practical issues prevent universal application.
Passive Atmospheric Samplers
Functionality
- Passive samplers measure ambient gases in the atmosphere without requiring power, through diffusion.
- Various designs and chemical reactions employed for specific gases like ammonia (NH3), ozone (O3), and nitrogen dioxide (NO2).
Impact of Air Pollution on Health and Environment
Bioindicators and Biomonitors
- Bioindicators: Qualitatively assess biotic responses to air pollution, indicating potential poor air quality.
- Biomonitors: Quantitatively assess pollutant concentration, such as through measurement in moss tissue.
- Spider webs have emerged as widely used biomonitors compared to other biological indicators.
Goal of Air Monitoring
- The ultimate aim of air monitoring is to protect both the environment and human health effectively.
Causes of Air Pollution
- Examining case studies like Delhi, particularly during events like the Hindu festival Diwali, illuminates acute pollution events due to:
- Crop stubble burning
- Emissions from transportation and industry
- Meteorological factors (cold mountain air, inversion)
- Topography (Himalayan effects).
Conclusion
Summary of Coverage
- Recap of air pollution:
- Definition and significance
- Measurement techniques
- Causes with specific focus on Delhi