The following article, by Dr George Crisp, first appeared in Medical Observer on 5th Sep 2011. It appears below with the kind permission of Medical Observer.
AIR pollution has been recognised as a major contributor to ill health for centuries.
While some of the acute effects of smogs, wood and coal burning have been obvious even prior to modern medicine, it is only recently we have started to realise the far greater and more insidious consequences of chronic exposure.
Worldwide, more than 800,000 deaths are now attributed to outdoor air pollution, with annual mortality in the US and the UK 100,000 and 30,000, respectively.
When the consequences of morbidity, lost productivity and lost years of life are considered, the global cost runs into trillions of dollars.
It is a largely silent but truly massive economic and public health issue.
Large epidemiological studies, supported by toxicological and clinical data, have confirmed a wide range of diseases are related to air quality.
There is strong evidence for a causal relationship between air pollutants and respiratory conditions such as COPD, asthma and lung cancer, and cardiovascular diseases, acute myocardial infarctions (AMI) and arrhythmias.
This is occurring even with exposure to low concentrations well below current guideline levels.
Air pollution refers to the introduced chemical, biological or particulate matter in the atmosphere that harms human health and other organisms, or damages the natural or built environment, with SO2, NO2, CO, volatile organic compounds and particulate matter (PM) the major primary pollutants.
Regulation and technological advances have reduced air pollutants, most notably SO2 and lead, but increasing traffic congestion and energy consumption result in a rise in pollutant emissions, and greater urban density and growth lead to greater human exposure.
Living near a busy road is a serious health hazard, with more than twice the number of Australians killed by traffic fumes than motor vehicle accidents. Research shows 15% of all asthma cases are linked to residential proximity to major roads(1).
A recent meta-analysis found traffic related pollution was the largest single population attributable factor for AMI. Exposure for just a few hours a week can trigger cardiovascular events, but longer term exposure can reduce life expectancy by years(2).
Particulates are liquid/solid droplets composed of nitrates, sulphates, organic compounds and heavy metals, and cause up to 80% of adverse health effects.
It is the very size of these particles that predominantly determines their damaging effects. Large particles are mostly filtered out in the airway, while the very smallest particles deposit deep within the lungs. Diesel-powered engines are the largest source of very fine particles, and produce up to 100 times the emissions of petrol engines.
A recent study in the European Heart Journal(3) found the adverse vascular effects of diesel exhaust inhalation are mediated through combustion derived nano-particulates. A single urban diesel four-wheel drive car may result in $3000 per annum in community health costs, it said.
There are compelling health and cost benefits to be gained by reducing pollution. Studies have repeatedly documented that even small reductions in fine particulate pollution can improve health outcomes.
The US Environmental Protection Agency calculates the 1990 Clean Air Act is currently saving 160,000 early deaths, 130,000 heart attacks, 1.7 million asthma attacks and 13 million working days. By 2020, the Act will be saving the US economy over $2 trillion every year, it says. Similarly, significant health co-benefits occur from reducing air pollution. This includes increased physical activity, reduced water use and pollution – and, of course, reducing greenhouse gas emissions.
One solution to all of these interlinked problems would be to include health in all policy decisions particularly in energy, transport and urban planning.
(1) A breath of fresh air please. The Lancet (Editorial)
(2) Public health importnce of triggers of myocardial infarction: a comparative risk assessment. ( Nawrot et al )
(3) Combustion-derived nanoparticlate induces the adverse vascular effects of diesel exhaust inhalation ( Mills et al )