Air Monitoring 15
Aerosols in Europe
An aerosol is defined as a stable suspension of solid and liquid particles in the atmosphere. Aerosols are found throughout the environment; they are very important for public health and the understanding of their dynamics is required for the quantification of their effects on humans.
The requirement to measure aerosols in range of fields has increased dramatically over the last two decades. As a result there are now a large number of instruments on the market ranging from small portable devices for personnel exposure monitoring to research laboratory based instrumentation.
Airborne particulate matter is a complex mixture of many different chemical species originating from a variety of sources. Particulate matter can act as transport medium for several chemical compounds, as well as, for biological material, which are absorbed or adsorbed on them. The role of particles in the atmosphere is very important both for effects on air pollution and climate. The 2007 Intergovernmental Panel on Climate Change identified aerosols (and clouds) as representing the single largest uncertainty in quantifying past climate change and in predicting future climatic trends
In recent years, extensive research effort has been invested in examining the relationship between exposure to ambient particulate matter (PM) and resulting health effects. Data from epidemiological studies demonstrate associations between ambient particulate concentrations and increased morbidity and mortality, while data from toxicological studies provide potential biological explanations for these observed associations.
Percentage of urban population resident in areas for days per year with PM10 concentration exceeding daily limit value, 1997-2009 (EU-27) Source
http://www.eea.europa.eu/legal/copyright. Copyright holder: European Environment Agency.
guidelines are: Annual mean, 10 µg/m3 PM10. The 24-hour mean is 25 µg/m3
Ambient air quality standards have been introduced at national and international levels with the aim of protecting human health and the environment. The threshold pollutant concentrations described in the legislation are based on a detailed review of the scientific information related to their effects on human health. It has been shown that the size of particles is directly linked to their potential for causing health problems. Initially legislation was aimed at PM10 (effectively particles with an aerodynamic diameter below 10 µm diameter) but more recently attention has focused on PM2.5 (PM < 2.5 µm diameter). However there is still debate as to whether even smaller particles or a non-mass metric, e.g. particle number that is primarily responsible for the effects.
The current EU air quality standards for particulate are given in Table 1. For comparison the World Health Organization (WHO) air quality
Table 1: EU air quality standards for particulate matter Particle size PM2.5 Concentration 25 µg/m3 ** 50 µg/m3
Author Details: Ian Colbeck
School of Biological Sciences University of Essex, Colchester, CO4 3SQ
Email:
colbi@essex.ac.uk PM10 40 µg/m 1 year Averaging period 1 year 24 hours Legal nature
Target value entered into force 1.1.2010
Limit value enters into force 1.1.2015
Limit value entered into force 1.1.2005**
Limit value entered into force 1.1.2005**
Permitted exceedences each year
n/a 35 n/a
**Under the new Directive the Member State was able to apply for an extension until three years after the date of entry into force of the new Directive (i.e. May 2011) in a specific zone. Request was subject to assessment by the Commission. In such cases within the time extension period the limit value applies at the level of the limit value + maximum margin of tolerance (35 days at 75 µg/m3
for daily PM10 limit value, 48 µg/m3 Adapted from
http://ec.europa.eu/environment/air/quality/standards.htm for annual PM10 limit value).
for PM2.5 and 20 µg/m3 for PM2.5 and 50 µg/m3
for for PM10.
Directive 2008/50/EC not only includes an objective for PM2.5 but also considers an exposure related objective and target reduction based on an average exposure indicator (AEI). This is determined as a 3-year running annual mean PM2.5 concentration averaged over selected monitoring stations in agglomerations and larger urban areas. Details are given in Table 2.
There is considerable literature concerning patterns and trends of ambient aerosols and their concentration characteristics. In Europe, PM measurements are performed mainly in urban areas for the purpose of monitoring human PM exposure. In general annual PM10 concentrations are higher in central and southern Europe than in the UK and Nordic countries. In 2009 the annual limit value for PM10 was exceeded most often in Poland, Italy, Slovakia, the Balkan states and Turkey. Across Europe local anthropogenic emissions (traffic, industries)
www.envirotech-online.com
IET September / October 2012
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