Where does air pollution come from?

Vehicle, combustion, and “hidden” pollution sources

• Several comments stress non-exhaust emissions: tire and brake dust are seen as major particulate sources, especially in cities and colder climates with studded tires and road sand.
• EVs are noted as better for brake dust (regen braking) but potentially worse for tire wear due to higher weight and fast acceleration.
• Wood burning (fireplaces, stoves, BBQs) is highlighted as a surprisingly large and often affluent-driven source of local particulates, in some places rivaling traffic.
• Sea spray and other “natural” PM2.5 sources exist, but commenters are unsure how their toxicity compares to combustion-derived particles.

Health impacts and metrics (deaths vs QALYs)

• Debate over whether pollution “mainly kills the frail who would die soon anyway” is pushed back on: people report clear symptom relief during COVID traffic reductions and when leaving dense cities.
• Pollution is framed as a “frailty multiplier” like starvation, shifting people into disease and death they might otherwise avoid.
• Discussion favors considering quality-adjusted life years (QALYs), but some argue lifespan and healthspan effects are roughly proportional, so death counts already imply large morbidity.
• Examples cited include asthma (especially children), cardiovascular damage, developmental harm, cancer, and possible links to hypertension.

Data, attribution, and monitoring

• Some skepticism about “hard proof” is met with references to extensive citations; others note that many estimates (especially outdoor contributions) are model-based.
• Indoor pollution from cooking, fireplaces, oil lighting, candles is widely accepted as clearly harmful.
• Under-5 air-pollution death rates in several African countries prompt debate over whether other causes (malnutrition, infections) are larger but correlated.
• Local monitoring gaps are a concern: polluted small towns may “disappear” in national stats if sensors are sparse or badly placed; micro-environments within cities (busy streets vs parks, beaches) can diverge strongly from city averages.

Inequality, politics, and regulation

• Pollution burden is seen as regressive: poorer communities live nearer roads, ports, and industrial sites, echoing industrial-revolution patterns.
• Attempts to curb urban pollution (e.g., stricter vehicle zones) often face intense political backlash.
• Shipping’s SO₂ cuts (IMO 2020) surprise some; possible explanations include port rules, fines, insurance constraints, and the fact that costs were imposed uniformly so operators could all raise prices.

Agriculture, consumption, and global trends

• Many sectors’ emissions are declining, but agricultural ammonia and methane show little progress; changing global diets is seen as harder than regulating a few industrial actors.
• Meat and dairy, especially cattle, are repeatedly flagged; lab-grown meat is discussed but current environmental gains seem unclear.
• Commenters stress “outsourced pollution”: rich countries claim green progress while importing goods (and associated emissions) from elsewhere; per-capita consumption-based CO₂ figures for some wealthy countries remain high or rising.

Personal mitigation and technology

• Individual steps mentioned: wearing well-fitted N95 masks in heavy pollution, using HEPA purifiers (commercial or DIY Corsi–Rosenthal/box-fan builds), monitoring indoor air, and considering solar for cleaner power.
• Balancing indoor filtration with fresh-air ventilation and CO₂ buildup is noted as an unresolved practical challenge.