Causes and Effects of Particulate Matter (Particle Pollution)

What is Particulate Matter?

Atmospheric particulate matter, better known as particulate matter or particulates or particle pollution are microscopic particles which are comprised of liquid or solid matter and suspended in the earth’s atmosphere. Created by both natural and man-made causes, particulates impact the earth’s climate, precipitation levels and can have substantial negative effects on human health. Particulates are the deadliest form of air pollution because of the ability for them to deeply penetrate the lungs and blood streams unfiltered. These particles vary greatly in size, composition, and origin.

EPA defines Particle Pollution or PM as,

“Particle pollution (also called particulate matter or PM) is the term for a mixture of solid particles and liquid droplets found in the air. Some particles, such as dust, dirt, soot, or smoke, are large or dark enough to be seen with the naked eye. Others are so small they can only be detected using an electron microscope.”

Particulate matter is often divided into two main groups, based on their size:

1. Inhalable coarse particles: These particles range from 2.5 micrometers to 10 micrometers in diameter (PM10 – PM2.5).
2. Fine particles: These particles are found in smoke and haze with a size up to 2.5 µm (PM2.5).

While Inhalable coarse particle are found near roadways and dusty industries, fine particles can be directly emitted from sources such as forest fires, or they can form when gases emitted from power plants, industries and automobiles react in the air.

Causes of Particulate Matter

Natural Causes

• Volcanoes – Erupting volcanoes eject large quantities of particulates including volcanic ash and gases into the atmosphere, volcanic eruptions have been directly associated with climate change since studies began

• Dust storms – Strong winds can pick up vast clouds of dust which in turn are dispersed into the atmosphere and can take years to return to the surface

• Forest and grassland fires – Wood and grass smoke contain a complex mixture of particulates such as carbon monoxide and hydrogen cyanide, which are lifted into the air and rest in the atmosphere

• Living vegetation – Vegetation that emits particles to the air, such as isoprene, methanol and spores. These particles can be carried upwards by the wind and add to the level of particulates in the atmosphere

• Sea spray – Due to the large amounts of plastics that have broken down to Nano scale, particles and can be found in ocean water all over the world. These hazardous particles can be thrown into the air by strong sea spray

• Tornado’s and hurricanes – These powerful weather systems can pick up large quantities of resting dust and pollutants just from the countryside, let alone when they pass through cities and encounter cement dust and higher levels of overall pollutants

Man Made Causes

• Coal Combustion – Coal burning is still used in the majority of countries to generate heat and supplying energy, the burning of coal directly increases the amount of carbon monoxide and other hazardous particles into the atmosphere

• Oil Combustion – Used for fueling vehicles, which in turn emit a large number of exhaust fumes containing hazardous particulates all over the globe, in huge quantities. Due to the large amounts if these pollutants in cities, countless deaths are caused by particulates

• Wood combustion – The burning of wood is a wide scale cause of particulates, used for many purposes such as heating and generating power, the combustion process sends many toxic cocktails of pollutants into the atmosphere, such as soot

• Construction – Cement dust is a large portion of overall global pollutants, because of the dust’s small particle size, it can hang around in the air for quite some time. The use of vehicles in the construction industry and other known pollutants makes the construction industries in dire need of reforming

• Demolition – Huge amounts of dust are thrown into the air during even the smallest demolition project, these particles are picked up into the wind, and again due to the small size of said particles, they can stay airborne for a very long time

• Road dust – Roads are covered in microscopic dust and pollutants which are sent airborne by the air pressure changes and wind caused when a car uses a road, this happens all over the planet

• Power plants – Plants that burn fossil fuels for energy and even nuclear plants disperse particulates on a huge scale, vast plumes of smoke will be found at most power plants, dispersing hundreds of cubic feet of pollutants every hour

• Industrial – Manufacturing plastics and other materials which create toxic fumes are dispersed into the oceans, air and land. Which in turn adds to the huge amount of man-made pollutants

• Agricultural – Pesticides and other volatile chemicals are sent into the air via sprayers and liquid jets. Again the agricultural industries use a large number of vehicles running on fuels such as petrol and diesel, which all attribute to the level of air pollution

• Livestock – The livestock industry creates a huge amount of particulates which are dispersed into the air, ground and oceans. Even the animals themselves have been found to disperse great quantities of methane into the atmosphere

• Deforestation – Felling trees for various industries impacts the rate at which trees would naturally produce carbon dioxide worldwide, however recent trends of replanting and harvesting cycles have reduced this

• Poor condition of anti-pollution technology – In recent years the world has made a strong effort to combat the high levels of lethal pollutants, but unfortunately, some countries have produced very minimal reductions in annual pollution output

• Tobacco smoke – Hundreds of toxic chemicals are present in tobacco smoke, and due to the millions of smokers worldwide, this leads to further pollution

Effects of Particulate Matter

Climate Effects

• Volcanic eruptions – These have been linked with changes in the earth’s climate. For example, in the 1600s a volcanic eruption in Peru (Huaynaputina) is believed to have caused a devastating famine in Russia which resulted in nearly 2 million deaths

• Eruption of Mount Pinatubo – The eruption of 1991, the second largest terrestrial eruption of the 20^th century, led to a world-wide temperature reduction of 0.5 degrees Celsius which lasted several years

• Weather – Particulates are thought to affect weather on a regional scale and have been linked to the failure of the Indian Monsoon. Due to suppression of levels of evaporation of water from the Indian Ocean

• Drought – Aerosol haze and particulates are believed to be pushing tropical rainfall southward, leading to a number of droughts across the world. Droughts worldwide have been occurring much more often since recording began

• Rainfall declines – A decline in Australian rainfall have led researchers to believe the increase of pollutants from Asia have shifted multi-latitude systems southward

• Greenhouse Gasses – Our atmosphere’s molecular make up has changed dramatically since the industrial revolution. The increase in global industries has led to a build-up of so called greenhouse gasses in the atmosphere, which prevent heat from escaping the planet leading to global warming

• Global dimming – Reductions in the earths direct irradiance have led researchers to believe that the increase in particulates in the atmosphere has impacted this, global dimming also creates a cooling effect, counteracting the heating of the greenhouse gasses

• Ocean acidification – Due to the higher levels of carbon dioxide released by human activity. An estimated 30-40% of carbon dioxide dissolves into the oceans, causing harmful effects to ocean life such as coral bleaching.

Health Effects

• Asthma – A rising rate of diagnoses have been linked to the increased levels of fine pollutants in countries worldwide, particularly in areas with higher pollution

• Lung cancer – Fine particles that penetrate deep into the human respiratory system and attack the bronchi, affecting the health of the lungs and leading to cancerous growths

• Cardiovascular disease – Numerous different particulates have drastic effects on the heart and its functions, again caused by the fine particulates that easily pass into the human system unfiltered

• Premature delivery – Exposure to high levels of air pollutants has led to an increase in the amount of failed pregnancy’s, especially in towns and cities with higher levels of pollution

• Birth defects – Particulates pass through the mother and into the child at any point of the pregnancy and can lead to a wide range of birth defects

• Premature death – Typically higher in regions with high levels of air pollutants and aerosols

• Vascular inflammation – Caused by a plaque build-up in the arteries, directly caused by particulates inhaled

• Atherosclerosis – Hardening of the arteries that reduces elasticity, leading to heart problems, also caused by plaque build-up

• Radiation exposure – A large number of particulates are formed up of radioactive material such as uranium and thorium, which is then inhaled or finds its way into crops which in turn are consumed

• One Million Deaths – Every year are associated directly to the air pollution caused by the coal industry alone

• 5 Million Deaths – Every year are believed to be caused by particulates worldwide

Vegetation effects

• Mortality – Stomatal openings are clogged, leading to failures during the photosynthesis process

Image credit: Adam , NASA