Despite having a clear understanding of traffic pollution and its impact way back in the 1990s, air pollution in many urban areas and cities across the world continues to get worse! This is serious stuff. Just in the UK alone, air pollution from traffic is estimated to be responsible for the early deaths of twenty to thirty thousand [30,000] people, every year! That is equivalent to the entire population of a small town dying every year. Across the world, there are many more deaths and health problems caused by air pollution. You would probably expect this to be taken seriously. Some do take it very seriously and the demand for solutions is increasing. This article outlines the challenges and offers some solutions.
Air pollution refers to a substance in the air that has undesirable consequences. Typically, these consequences include one or more of the following:
» Irritation, headaches, and/or difficulty breathing
» Health problems, including birth defects, lung and heart disease, cancer, heart attack, and death
» Damage to vegetation and crops
» Climate change, and impact on the oceans
The impact of the pollutants usually increases with increasing concentrations, and the amount of time you are exposed to those concentrations. Governments set (legal) limits on concentrations of pollutants that cause health problems, so that the average person would probably be safe when exposed under typical situations. [However, roadside workers, for example, might be exposed to higher concentrations for longer periods than the average person.]
Public safety relies on concentrations remaining below these limits. However, in cities across the world these limits are being exceeded.
Note that in the case of pollutants that can cause cancer (known as carcinogens) there is no safe level. This means that any quantity, or concentration, might trigger cancer, but the smaller the quantity the smaller the probability of it happening. Limits for carcinogens reflect a probability that health experts consider safe or acceptable.
There are primary and secondary pollutants:
» Primary pollutants correspond to vehicle emissions, most of which come out of the exhaust pipe.
» Secondary pollutants form when primary pollutants react in the atmosphere, the most common example of this being ozone that forms in photochemical smog on (hazy) sunny days. This can occupy an area larger than the emissions source (e.g. the urban area) and be displaced from it, depending on wind patterns.
Many pollutants are in the form of gases, but some are small particles or aerosols.
An example of particulate emission is smoke, which is often seen coming out of diesel vehicles (and rarely petrol vehicles) when they accelerate or go up an hill. These small particles, especially those below 2.5 micrometres (called PM2.5) represent a major concern because they penetrate deep into the lungs and may pass into the blood-stream. These particles also contain carcinogenic [cancer causing] chemicals. Note that you cannot always see particulate emissions.
As a member of the general public, or even a green supporter, you could be forgiven for feeling confused over the environmental credentials of diesel vehicles. In the past they were [misleadingly] promoted as clean, or green, vehicles; but now it is clear they represent a major threat to human health in urban areas across the world. The reason for the confusion is a matter of priorities: global climate change versus human health.
Diesel vehicles were supposed [*] to offer better miles per gallon and lower emissions of carbon dioxide, compared with petrol vehicles. So this meant [in theory] that diesel vehicles would have less of an impact on climate change.
However, it has been known, at least as far back as the 1990s, that diesel emissions of particulates are very bad for human health; and that diesels also emit high levels of nitrogen oxides, another pollutant that impacts on health. Diesel vehicles in the UK alone may be causing twenty to thirty thousand deaths every year. That is a very high price to pay to mitigate climate change.
* The emergence of recent scandals about diesel emissions and fuel consumption, and actual on road performance, calls into question the suitability of diesel vehicles.
Consequently, the authorities are now waking up to this and there is growing demand to sort out the problem of diesel vehicles and their toxic emissions.
The World Health Organisation and other air quality organisations have identified that many cities across the world are exceeding air quality limits. However, it is not just the big cities, even smaller urban areas are exceeding these limits. Given that this means more deaths, health problems and probably fines for breaking legal limits, action is expected.
In the case of London (and elsewhere) this means establishing a clean air zone (or low emissions zone, or ultra-low emissions zone). In 2023, the London Mayor extended the clean air zone across the whole of London. It is expected that other cities might follow.
However, the social impact can be significant, depending on the specific implementation details of a clean air zone. Therefore, the relevant communities should be consulted, a sufficient period of notification should be provided prior to implementation, and changes should be made gradually to allow people to adapt.
Here is a list of relatively simple [but not necessarily painless] things that can be done to improve urban air quality.
» Create pedestrian only areas, especially where there are lots of people.
» Implement low emission zones: areas for low, or zero, emission vehicles only.
» Set up areas where diesel vehicles are not allowed. This could be challenging for deliveries though; so perhaps schedule deliveries outside of busy periods and/or encourage a new zero emission urban logistics service.
» Modify diesel vehicles with technologies that improve their emissions. [See Environmental ideas: Reducing toxic emissions from diesel powered vehicles (PDF, 358kB)]
» Switch bus fleets from diesel to gas, alcohol, hydrogen or electric power.
» Target the worst 10 percent of vehicles (which can cause up to half of all the pollution). At the simplest level, this could be enforced by police and traffic wardens by recording the number plates of smoking vehicles, and sending their owners warning letters then fines for repeat offenders. [More advanced solutions are available based on the use of technology.]
» Often, dealing with air pollution is a matter of setting priorities, and making trade-offs. Therefore, first set your relative priorities.
» Be aware that on the boundary of a restricted area there might be a negative impact. For example, unauthorised vehicles that previously drove through that area might now be making longer journeys around the perimeter, contributing to more congestion and emissions on other roads. Also, how do people change their behaviour when their vehicle is unauthorised but they still need access (e.g. deliveries, extra parking requirements, and switching modes of transport and times of day).
» You should think these ideas through carefully before implementation.
Wed 30 Aug 16:08:29 BST 2023