Particulate Matter

Particulate Matter

The World Health Organisation (WHO) believes particulates are affecting more people worldwide than any other pollutant. Primary health effects include damage to the respiratory and cardiovascular systems. Due to the small size of PM10 and PM2.5 particles, they can get deep into the lungs, and some may even get into your bloodstream.


Credit for Picture: Environmental Protection Agency

Particulate matter is often divided into three classes – coarse particles with a diameter of 10µm -2.5µm; fine particles 0.1 to 2.5µm and ultrafine, less than 0.1µm. Human hair has a diameter of 50-70µm and a grain of sand has a diameter of 90µm.

There are natural and made-made sources of Particulate Matter. Natural sources include sea salt and mold whereas human made sources come from vehicle exhausts, tyres, brakes, construction sites and industrial processes. Under the class PM10s typically include dust and pollen. PM2.5 typically refers to products of combustion, organic compounds and metals.

Health effects

The inhalable dust fraction is the fraction of dust entering nose and mouth which may be deposited anywhere in the respiratory tract. The thoracic fraction is the fraction that enters the thorax and is deposited within the lung’s airways. The respirable fraction is what is deposited in the gas exchange regions (alveoli).

Because of their small size, particles of the order of ~10 micrometers or less (PM10) can penetrate the deepest part of the lungs such as the bronchioles or alveoli.

Fine PM or PM2.5 tend to penetrate into the gas exchange regions of the lung (alveolus), and very small particles (< 100 nanometers) can pass through the lungs to affect other organs. Particulates emitted from diesels are typically in the size range of 100 nanometers (0.1 micrometer). These particles can also carry carcinogens like benzopyrenes adsorbed on their surface.

According to the European Environment Agency Particulate pollution contributed to ~370,000 premature deaths in Europe during 2005 and The Lancet (380: 2224–2260) quotes 3.22 million deaths globally in 2010. The British Medical Journal stated that an increase in estimated annual exposure to PM 2.5 of just 5 µg/m3 was linked with a 13% increased risk of heart attacks.

The World Health Organization (WHO) estimated in 2005 that “… fine particulate air pollution (PM(2.5), causes about 3% of mortality from cardiopulmonary disease, about 5% of mortality from cancer of the trachea, bronchus, and lung, and about 1% of mortality from acute respiratory infections in children under 5 years, worldwide.”. The Journal of Toxicology and Environmental Health, states short-term exposure at elevated concentrations can significantly contribute to heart disease. A 2011 study in the Lancet concluded that traffic exhaust is the single most serious preventable cause of heart attack in the general public, the cause of 7.4% of all attacks.

These are the limits the WHO have put on Particulate Matter:

PM10 20µgm3 annual mean

PM10 50µgm3 24 hour mean

PM2.5 10µgm3 annual mean

PM2.5 25µgm3 24 hour mean

This country has the following standards:

PM10 50µgm3 24 hour mean

PM10 40 µg/m3 annual mean

PM2.5 25 µg/m3 annual mean