The Challenge of our Times (Part II) Pollution

European mean tropospheric nitrogen dioxide (NO2) vertical column density (VCD). Credits: University of Heidelberg

Chapter 2: CLEAN

The Challenge of our Times (Part II) Pollution

Pollution & Waste

Remember pollution? These days all we seem to talk about is climate change and greenhouse gas emissions. CO2, the main greenhouse gas, is not classified as pollution because it is a natural component of the atmosphere and needed by plants in order to carry out photosynthesis. It may harm us indirectly, via climate change or even via increased ozone pollution (12), but it does not directly affect respiration.

Lots of other substances, however, do have a direct effect on our health and our immediate habitat. Although it is true that enormous improvements have been booked in minimizing pollution and waste, it still exists and it still harms us. In Belgium, we are rediscovering air pollution, thanks in part to the smog alarms. Contrary to what people may think, the smog situation in Belgium has actually improved over the years. What has changed is our understanding of the health risks. As Tim Nawrot and his colleagues outline in their article on fine particulate pollution, the risks are very real. This is why the SMOG boards have begun to appear on our highways. But fine particulate pollution is just one part of the story. How bad (or good) is the overall situation in this country?

Air Pollution

According to the European Environment Agency, emissions of most air pollutants in Europe have fallen significantly since 1990, resulting in improved air quality. This is also true for congested Flanders. But problems remain, especially in four key areas: (fine) particulate matter, NOX, ozone and NMVOC.

Particulate matter pollution turns out be more dangerous than previously thought. The bigger particles, the dust that irritates eyes, nose and threat—but not the lungs—are the least dangerous. Anything smaller than 10 micrometers in diameter, however, can reach deep into the lungs and thus cause a range of health problems. As a result, PM 10 and PM 2.5 (referring to their maximum size in micrometers) have been monitored for some years now. Although concentrations have declined markedly since the early 1990s, in Flanders the problem is not under control. In fact, according to Tim Nawrot from the University of Hasselt, Flemish air quality is one of the worst in Europe. Year average concentrations are still above the target set by the European Commission and the number of days per year that the concentrations exceed the ‘safe’ limit remains too high. Furthermore, it turns out that ‘ultrafine’ particles (PM 1 and PM0.1), not yet monitored systematically, are proving to be more dangerous for human health than even PM2.5. The key culprits behind fine particle pollution: diesel motors (motorised transport and home heating), industry (the Ghent canal zone is particularly bad given the steel works and coal power plant) and agriculture. But what exactly are these fine particles and why do they harm us and our environment? The problem is that many of these particles are toxic substances such as NOX, Ozone and many others.

NOX pollution—the term itself sounds chilling, as it should, since it is nasty. NOx is a generic term for mono-nitrogen oxides (NO and NO2), which are produced during the combustion of fuels, especially coal and oil. In the air it reacts with other compounds to form nitric acid vapour, Ozone and a range of other toxic substances. These are at least one part of the fine particle story, causing lung damage, heart disease aggravation and possibly cancer. NOX clearly is not under control. According to the European Environment Agency, NOX emissions for the EU-27 as a whole are still 20% above the ceiling set for 2010. The main cause of this is the continued growth in road transport. Belgium, and Flanders in particular, are not likely to achieve the 2010 EU target. Oh, and NOx is a greenhouse gas too, contributing to the climate problem.