Air Pollution: Time to clear the air?

Author: Dr Leila Battison

Just how clean is the air that we breathe? At the end of last year, the European Environment Agency (EEA) and the World Health Organization (WHO) published independent reports on global air quality, with some pretty murky conclusions. With around 92% of the global population living in areas where air pollution exceeds WHO safe limits, the risk to health is considerable. In fact, the EEA calculated that air pollution contributes to over 450,000 premature deaths in Europe alone each year (1).

This phenomenon is not limited to developing countries. December 2015 saw the first ever air pollution ‘red alert’ in Beijing as pollution levels soared to over ten times the recommended safe level. The alert caused schools to be closed, outdoor construction to be halted, and travel by car limited (2). And at the beginning of 2017, London exceeded its annual limit for pollution in just five days. During mid January, the city set a modern pollution record, with the first ‘very high’ pollution alert issued under a new monitoring system. City-dwellers were advised to spend less time outdoors and to contact their GP if they were feeling unwell (3).

Scenes in pollution-ridden cities in the last couple of years are reminiscent of those during the Great Smog of London in 1952, where smoke from inner city factories and domestic coal fires settled to the ground and stuck around for an entire week. The noxious fumes are thought to have caused up to 12,000 deaths in the city (4) and was recently portrayed in the Netflix series The Crown where the newly crowned Queen Elizabeth II was torn as to whether to ask then Prime Minister Winston Churchill to resign over his apparent dismissive attitude towards the actual reality of the disaster. After the fumes had cleared, the British government brought the first Clean Air Act into effect, which should have rendered future ‘pea soupers’ impossible. This legislation put limits on the amount of black smoke that could be emitted from chimneys, trains, and industrial furnaces, and after some modernizing amendments, is still in force today. Yet, despite this, and in the face of the ever-greening of industry, air pollution is still reaching critical levels in many cities. Perhaps it is time for a reassessment of the causes and effects of declining air quality in the modern world.

Pollutants in the air essentially consist of unwanted gases, as well as tiny particles that are small enough to be suspended in the air. The news is saturated with the greenhouse effect and global climate change associated with the emission of carbon dioxide and methane, but the sources and effects of polluting particulate matter are less well-understood.

Very fine particles that are at most 2.5 microns – one 400th of a millimeter – across, are termed PM2.5. These tiny particles are commonly emitted by road vehicles, and are small enough to be swept up in air currents and distributed far from their source under certain weather conditions (5). Larger particles, termed PM10, are up to 10 microns across – still only one 100th of a millimeter – and are emitted into the atmosphere by road vehicles and wood burning, as well as the dust from construction and agriculture (6).

It might be hard to imagine how such vanishingly small bits of stuff could be so damaging, but even though they are too small to see or smell, they can be responsible for a number of fatal conditions. PM2.5 is small enough to be inhaled and enter the blood, and has been linked to asthma, lung cancer, and even heart disease (7).

In addition to these fine particles, noxious gases such as sulphur dioxide, nitrogen dioxide and ground-level ozone are emitted during the burning of fossil fuels and from vehicles and central heating boilers, leading to higher concentrations in cities, and a higher instance of pollution-related illnesses and deaths.

The recent EEA report found that people living in urban areas are at the highest risk, with over 85% exposed to unhealthily high levels of PM2.5. Within Europe, regions of Bulgaria, Poland, and the Czech Republic suffer the most, as a result of these countries’ dependence on coal-fired power stations (8). Worldwide, rapidly industrializing countries such as Egypt, Turkmenistan, and Afghanistan have the highest death rates caused by ‘outdoor’ air pollution, which accounts for up to three million deaths per year. When ‘indoor’ air pollution is also considered, including those particles produced by cooking fires and wood smoke, the WHO reports that air pollution is linked to a staggering one in every nine deaths worldwide (9).

These statistics aren’t what we’d expect from a forward-looking modern world, and indeed it’s not all bad news. Between 2000 and 2014, the levels of coarser PM10 particles actually fell across 75% of Europe, and in general the wealthier countries are getting better at controlling the quality of their air. With interventions to promote sustainable transport, improved waste management, and renewable energies, developed countries have the means to cut back on the fossil fuel burning practices that are the primary cause of polluted air. To this end, North America has thus far been more successful in improving air quality than Europe, since many European countries still rely on diesel fuel and intensive farming methods that emit large amounts of methane and ammonia (10).

In contrast, poorer countries, especially those in south-east Asia and the western Pacific, are experiencing ever-worsening air pollution. Their rapid industrialization without the support of expensive environmentally friendly technologies are making them helpless in the face of their own smothering smog. And with nearly two out of every three deaths in these regions resulting from lung cancer, stroke, and heart disease, all of which are compounded by rogue gases and particles in the air, it couldn’t be clearer that the time to act is now. We can only hope that measures are put in place before another Great Smog strikes, bringing with it a health crisis on a scale never seen before.




Copyright: Image of Warzawski by Radek Kołakowski (2.0 Creative Commons Licence, Wikimedia Commons)