Questions on Particulate Matter

1. What is Particulate Matter (PM)?
2. How does PM affect human health?
3. How are we exposed to PM?
4. Should current PM guidelines be reconsidered?
5. Conclusions on Particulate Matter

See also:
General issues & Recommendations

1. What is Particulate Matter (PM)?

Particulate matter is the sum of all solid and liquid particles suspended in air, many of which are hazardous. This complex mixture contains for instance dust, pollen, soot, smoke, and liquid droplets. More...

1.1 These particles come in many different size ranges such as coarse, fine and ultrafine. They also vary in composition and origin. More...

1.2 Particles are either directly emitted into the air by sources such as combustion processes and windblown dust, or formed in the atmosphere by transformation of emitted gases such as SO₂. More...

1.3 In Europe, sulphate and organic matter are the main components of particulate air pollution in terms of the mass of the particles. Mineral dust, nitrate, and soot can also be major components under certain conditions. More...

2. How does Particulate Matter (PM) affect human health?

2.1 In Europe, long-term exposure to current ambient particulate matter concentrations may affect the lungs of both children and adults and may reduce life expectancy by a few months, mainly in subjects with pre-existing heart and lung diseases. More...

2.2 Ambient particulate matter is responsible for harmful effects on health, even in the absence of other air pollutants. Both fine and coarse particles have been shown to affect health, in particular the respiratory system. More...

2.3 Fine particles are more dangerous than coarse particles. Apart from the size of the particles, other specific physical, chemical, and biological characteristics that can influence harmful health effects include the presence of metals, PAHs, other organic components, or certain toxins. More...

2.4 When particulate matter is combined with other air pollutants, the individual effects of each pollutant are cumulated. In certain cases, especially for combinations of particulate matter with ozone or allergens, effects were shown to be even greater than the sum of the individual effects. When particulate matter interacts with gases, this interaction changes its composition and, therefore, its effects. More...

2.5 Certain groups of people are more susceptible to suffer health effects due to ambient particulate matter. These include elderly people, children, people with a pre-existing heart and lung disease, asthmatics, and socially disadvantaged and poorly educated populations. More...

2.6 Because some persons are vulnerable even at low concentrations of ambient particular matter, no threshold has been identified below which nobody’s health is affected. More...

3. How are we exposed to Particulate Matter (PM)?

3.1 Studies on human populations suggest that a number of sources of particulate matter, especially motor vehicle emissions and coal combustion, are linked to adverse health effects. More...

3.2 Personal exposure depends both on particulate matter levels in ambient outdoor air and on specific indoor sources of particulate matter such as smoking or exposure at work. More...

3.3 The impact on public health of long-term exposure to particulate matter is probably larger than that of short-term exposure to peak concentrations. Long-term exposure particularly affects populations living near busy roads. More...

4. Should current PM guidelines be reconsidered?

4.1 Reductions in ambient particulate matter concentrations have had some positive impacts on public health. Changes in the composition of particulate matter might also reduce its adverse health effects. More...

4.2 Guidelines are recommended to be set for both short-term and long-term exposures to ambient particulate matter. More...

4.3 Current WHO Air quality guidelines describe the relationships between exposure to particulate matter and various health effects, but they recommend no specific maximum exposure values. New scientific evidence justifies reconsidering these relationships and developing guideline values both for fine and coarse particles. More...