Air pollution doesn’t feel like a topic until it is. One day you’re revising IB ESS, and the next you’re looking at an air quality alert on your phone and realizing the “environment” is not out there somewhere--it’s in your lungs.
For IB ESS (2026 first assessment), air pollution is a high-yield bridge between atmospheric systems, human activity, and public health. Examiners love it because it rewards students who can do two things at once: explain the science clearly, then evaluate how societies respond.
When the AQI graph becomes personal
The fast revision checklist (what IB ESS expects)
Before you write a single paragraph in Paper 2 or interpret a graph in Paper 1, make sure you can do this from memory:
Link sources (transport, industry, homes, agriculture) to specific pollutants.
Define and use the “headline” pollutants: PM2.5/PM10, NOx, SO2, O3, CO.
Separate short-term health effects from long-term chronic outcomes.
Add at least two case studies you can flex for different questions.
Evaluate strategies using effectiveness, cost, equity, and feasibility.
For targeted practice on this exact subtopic, RevisionDojo’s 8.3 Urban air pollution hub is the cleanest starting point.
Where air pollution comes from (sources you can label in seconds)
In IB ESS, sources matter because they shape solutions. Different sources also dominate in different places.
Transport
Urban traffic is a reliable producer of NOx, particulates (especially from diesel), and precursor chemicals that help form ground-level ozone.
Industry and power generation
Burning fossil fuels in power plants and factories releases SO2, NOx, and particulate matter. That’s why policy often targets stacks and fuels, not just cars.
Domestic combustion and indoor exposure
In many regions, cooking or heating with solid fuels raises exposure to PM and CO indoors--often where ventilation is poor.
Agriculture and open burning
Crop burning and some farm emissions contribute to particulate formation and regional haze. It’s also a great place to show systems thinking in IB ESS: food systems, energy choices, and health outcomes are connected.
The pollutants you must know for IB ESS (and what they do)
Particulate matter (PM2.5 and PM10)
PM is the exam favorite because it links directly to health data. PM2.5 is small enough to penetrate deep into the lungs. In IB ESS language: it increases risk of respiratory and cardiovascular disease, and it is strongly associated with premature mortality at population level.
They always find a way
Nitrogen oxides (NOx)
NOx irritates airways and contributes to smog formation. It also acts as a precursor in reactions that create ground-level ozone.
Sulfur dioxide (SO2)
SO2 is associated with breathing difficulties and is a key contributor to acid deposition. In essays, it’s a neat pivot: some impacts are direct (airway irritation), while others are indirect through environmental change.
Ground-level ozone (O3)
O3 at ground level is formed when NOx and VOCs react in sunlight. It can reduce lung function and trigger chest tightness and coughing.
Carbon monoxide (CO)
CO reduces oxygen transport in the blood. It’s especially relevant when discussing incomplete combustion and indoor air pollution.
How air pollution affects human health (write it like a marker)
A good IB ESS answer is layered: immediate symptoms, then the longer arc.
Short-term (acute) impacts
In the short run, exposure can cause coughing, wheezing, throat and eye irritation, headaches, and aggravated asthma. In Paper 1, these often appear as spikes in hospital admissions following high pollution days.
Long-term (chronic) impacts
Over time, repeated exposure is associated with chronic respiratory disease (for example COPD), cardiovascular disease (including stroke risk), and increased lung cancer risk. The World Health Organization describes air pollution as a major global health risk, linked to millions of premature deaths each year--a statistic you can reference without needing to memorize a single perfect number.
Case studies you can actually use under exam pressure
Markers reward specificity, but they also reward relevance. Pick a few you can recall clearly:
London Great Smog (1952): a classic example linking coal combustion, SO2, and acute mortality.
Beijing: severe urban smog events tied to coal use and vehicle emissions.
Delhi: extreme PM2.5 concentrations and repeated public health alarms.
Los Angeles: photochemical smog and ozone formation driven by traffic and sunlight.
Management strategies (and how to evaluate them in IB ESS)
A trap in IB ESS is listing solutions without evaluating them. Instead, group them and judge trade-offs.
Technology
Catalytic converters, scrubbers, cleaner fuels, and renewable energy reduce emissions at source. Strength: measurable. Weakness: cost and uneven access.
Policy and planning
Emission standards, congestion charges, and air quality monitoring can change behavior quickly. Strength: scalable. Weakness: political resistance and enforcement challenges.
Behaviour change and urban design
Public transport, cycling infrastructure, and green spaces can lower exposure and reduce emissions. Strength: co-benefits (health, noise, equity). Weakness: slow rollout and requires public buy-in.
To practice evaluation in exam format, drill 8.3 Urban air pollution Questionbank and then do a timed attempt using RevisionDojo’s Mock Exams and Grading tools (especially helpful when your “evaluation” becomes vague).
Welcome to ESS
How this shows up in the IB ESS exams
Paper 1
Expect unfamiliar graphs: pollutant concentrations over time, AQI-style categories, or health statistics. Your job is to describe patterns, then explain mechanisms.
Paper 2
Common prompts include “Discuss impacts on human health” or “Evaluate strategies.” The winning move is to link pollutant --> mechanism --> health outcome --> response, with one case study.
Air pollution is one of the clearest examples in IB ESS where the environment becomes human health. If you can fluently connect sources to pollutants, pollutants to mechanisms, and mechanisms to short- and long-term outcomes--then evaluate responses with case studies--you’re ready for the questions that keep showing up.
When you want to move from “I understand it” to “I can score on it,” RevisionDojo is built for that jump: ESS Study Notes for clarity, Flashcards for recall, the Questionbank for exam-style reps, AI Chat for quick explanations, and Predicted Papers plus Mock Exams and Grading tools to make timing and evaluation feel normal.
