Cities of sickness: pollution, dementia and the modern condition

The journey from Tooting to the British Library tends to be a crowded affair at the best of times. Humans mash in ungainly fashion on the London Underground, though not mosh, as they tend to in Tokyo under almost brutal supervision. In the course of the walk, a breakfast of muffins and takeaway coffee is flavoured by furious fume blasts on Euston Road. The chill masks the choking pungency – slightly – but silent matter has already inhabited lungs and body. As receptacle, we take aboard this microscopic cargo, letting it fester through the course of the day.

Lingering contact with these joys of the global civilized effort cause predictable, lingering distress. The body, living ever longer in the face of natural depredations, responds accordingly. Health becomes a casualty, giving medical researchers and doctors their cue to seek more grant money and study this grand narrative of self-inflicted human decline.

These studies find their way into such journals as The Lancet, which published a gloom-filled study on January 4 examining trends linking the affect of major traffic to incidence of dementia, Parkinson's disease, and multiple sclerosis.

We aimed to investigate the association between residential proximity to major roadways and the incidence of these three neurological diseases in Ontario, Canada.

The researchers had already noted previous doomsday assertions "that living near major roads might adversely affect cognition." In March last year, a team of investigators focusing on children from 39 schools in Barcelona in Spain published their findings on the effects of exposure to high and low traffic-related air pollution. They make grizzly reading for policy maker and parent.

In what resembles a dark tale of brain shrinkage before the beasts of industry, children from "highly polluted schools had a smaller growth in cognitive development than children from the paired lowly polluted schools." Cognitive measurements were all smaller for those exposed to a cocktail of elemental carbon, nitrogen dioxide and ultrafine particle number, all components of chronic traffic air pollution.

Earlier in 2016, the British Medical Journal (BMJ) also raked over the terrain of children's exposure to air pollution, examining it through the prism of dispensed medications for psychiatric orders and adolescents. The authors, focusing on Swedish examples, concluded that there was a link, though cautioned that "findings should be corroborated by others." In short, developmental neurotoxicants make you thick.

Little from these findings should startle, though they suggest the inexorable, and even remorseless drive of the human species to growth that retains a touch of suicidal desperation: to grow, but at what cost? Perhaps we all have a right to suffer in growth.

The cadaverous form modern living takes in the gargantuan concentrations that count for our modern cities was already interesting A. Lundberg in the mid-1990s.

Physical and toxic effects of air pollution can lead to psychiatric symptoms, including anxiety and changes in mood, cognition and behaviour.

Lundberg's study urged a greater understanding of the phenomenon of environmental trauma, something which could be done in the way people perceived and coped with environmental health risks, the effects of pollution on behaviour and neuropsychological functioning, and the use of neurotoxicologic evaluation techniques of air pollutants.

The Ontario study moved to the next stage, attempting to identify specific diseases that might arise for those unfortunates hugging or, at the very least, in proximity to the belching woes and effects of modern traffic. The cohorts of Ontario population-based cohort study were impressively vast, featuring adults between 20-50 years, with 4.4 million in one cohort (multiple sclerosis) and adults aged 55-85 years (2.2 million) in the other, covering dementia or Parkinson's disease.

The researchers had obviously seemed to be on the ball with this one, taking into account access to neurologists, exposure to various pollutants, and adjustments made for the contexts of such conditions as brain injury, diabetes and neighbourhood income.

The findings indicate that the large cohort featuring the older population focused and living in proximity to heavy traffic "was associated with higher incidence of dementia, but not with Parkinson's disease or multiple sclerosis." One in 10 cases were identified for those living near roads affected by noise and air pollution.

The work is another clarion call about the vicissitudes of relentless urbanisation. As the lead scientist on the project Hou Chen explained,

Increasing population growth and urbanisation has placed many people close to heavy traffic, and with widespread exposure to traffic and growing rates of dementia, even a modest effect from near-road exposure could pose a large public health burden.

As is the nature of the business of risk, other scientists urged caution. Don't up stakes and go to the country just yet. "The analyses are exceedingly complex," suggested neuroscientist John Hardy of the University College of London, "and this always leads to concerns that the analytic complexity is hiding confounding factors in the analytic pipeline." By no means a reassuring statement.

Despite throwing some cold water on the Ontario study, Hardy can hardly dispel the firm notion that cities are places of increasing sickness, at both the bodily and mental level. The propaganda about well-being is everywhere; the clinics are getting busier. The human being is in a state of suffering, and urban planners will be smacking their lips at the prospect of more employment. Sickness, as it has was in the past, will continue being good for business.