According to the 2010 Global Disease Burden Assessment, outdoor air pollution caused more than three percent of the annual disability and life lost. Rising due to urbanisation. Responsible for 50 000 deaths annually in the UK.

Air pollution associated with low birth weight, smaller heads, developmental disorders eg autism, type 2 DM, strokes, heart attacks (atherosclerosis), cognitive decline, slower development of lung function with reduced adult capacity (implication for COPD), onset of asthma, wheeze. Not just exacerbations of chronic lung disease!

Different kinds of pollution – particulates (different sizes eg PM1), nitrogen dioxide, sulphur dioxide.  Most PM10 from traffic, but natural sources too eg pollen, soil.  Wood burners! NO2 and SO2 falling as fewer power stations and less industrial output, but NO2 particular problem for urban centres where most commercial vehicles run on diesel.

Diesel engines also produce polycyclic aromatic hydrocarbons eg BaP (Benzo pyrene), maternal exposure a concern as linked to mental health and neurodevelopmental problems in children. Some also carcinogenic.

Particulates a problem for respiratory conditions. Often contain spores and pollen. Ozone associated with airway hyperresponsiveness.

Not just about degree of pollution – metereological factors (temperature, atmospheric pressure, low humidity etc) complicate. In Taiwan, pollution synergistic with dust mites for development of asthma.

Carbon deposits found in fetal side placental macrophages. 

MRSA and stenotrophomonas colonization in CF associated with maternal PM levels.

European study of 325 000 adults found mortality increased proportionally with levels of particulate matter, nitrogen dioxide and black carbon – even at levels below current EU/US/WHO standards. [BMJ 2021;374]

Southern California reduced PM levels and found less severe chronic lung problems.

1 hour commuting in Sao Paolo estimated to be equivalent to  5 cigs/d.  In London, travel to school is bulk of exposure (plus school breaks! Note locations!) esp stationary traffic.

What cars produce in lab tests is not the same as in the real world, even when manufacturers don’t cheat!

Low emission zones generally exclude cars, and may just divert traffic elsewhere, not much evidence that they help. London low emission zone has reduced NO2 slightly only.  Plan for ultra low zone. 

[Abigail Campbell, SPRING meeting 2019, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6016370/ ]