Description of individual pollutants and their adverse health effects

Gas heating

In addition to greenhouse gas carbon dioxide emissions, nitrogen oxide emissions are also significant.

Nitrogen oxides

Nitrogen oxides are formed by heat. 78% of the atmosphere is made up of stable nitrogen gas (N2) which is naturally oxidised by forest fires and lightning to form nitrogen oxides. The same process takes place in human-induced combustion, for example in cars burning fuel, or in thermal power stations, or even in domestic stoves and boilers. In the latter cases, the main source of nitrogen is the nitrogen content of the air, and only to a much lesser extent the nitrogen content of the fuel used. Nitrous oxide in the air causes respiratory diseases, inflammation of the mucous membranes of the airways and the conjunctiva of the eyes, dilated blood vessels, and the formation of methahemoglobin. It can also cause genetic damage in humans.

Heat pumps

Heat pumps are powered by electricity, so they do not cause air pollution locally. Their pollution is primarily significant in fossil-fired power plants (gas and coal-fired), although filtering equipment can minimise air pollution per unit of energy produced, except for carbon dioxide emissions. The pollutants emitted are detailed under gas-fired and coal-fired plants. If the electricity generated is from solar, wind, or hydroelectric power, there is no air pollution.

District heating

Gas-fired district heating is generally used in Hungary, with the occasional biomass-based or waste-fired systems (in Budapest) providing heat. The air pollution per unit of thermal energy produced can be minimised, except for carbon dioxide emissions. In the case of biomass combustion, the carbon dioxide emitted is cycled through the plants and does not pollute the Earth's atmosphere. The pollutants are similar to those of gas heating, but in the case of biomass, the pollution is significantly lower (hundredths to thousandths) compared to wood combustion.

Wood combustion

Smoke from wood combustion contains harmful substances due to incomplete combustion. Wood combustion can also contribute significantly to emissions of volatile organic compounds, carbon monoxide, and certain heavy metals.

A detailed publication on the subject has been published.

Soot particles

Soot particles are organic particles composed of elemental carbon. They are often defined as "black carbon". Some of the fine particles emitted in combustion processes are soot particles; like fine particles, they are measured in mass (μg/m3). Like fine particles, soot particles are long-lived in the atmosphere. Therefore, they can travel long distances and be deposited in such remote places, like the Arctic. Recent studies have suggested that soot particles, which appear to be more dangerous to health than inorganic particles, are one of the main culprits behind human-induced climate change and the melting of polar ice caps.

Fine particles

Fine particles (PM2.5) are particles with a diameter of less than 2.5 micrometres (μm). Fine particles are measured by their mass; usually micrograms per cubic metre (μg/m3). In Hungary, fine particles from domestic solid fuel combustion account for 85% of particulate emissions, according to the Ministry of Agriculture. The vast majority of this comes from wood combustion. Fine particles are airborne for long periods and therefore travel long distances. For this reason, a significant part of fine particle pollution in Hungary comes from abroad, just as part of the Hungarian particle pollution reaches other countries and causes health damage there. In residential areas with high rates of wood combustion, concentrations of fine particle pollution can reach the same levels as those found on the most polluted Hungarian roads during the busiest hours. The morbidity and mortality from air pollution are calculated based on fine particle pollution, which is the air pollutant that causes the greatest number of years of life lost and premature deaths on earth.

 

Ultrafine particles

Ultrafine particles (PM0.1) are particles with a diameter of less than 0.1 micrometres (μm), i.e. less than 100 nanometres. They are measured by counting and are typically measured in particle counts per cm3. There are currently no official measurements of ultrafine particle pollution from domestic wood-burning in residential areas. The Clean Air Action Group has measured that there are extreme levels of emissions from domestic chimneys and that wood-burning in residential areas causes severe ultrafine particle pollution. In addition, indoor ultrafine particle pollution from wood combustion can be much more severe. Our measurements suggest that the first line of pollution is localised, with significantly lower particle numbers further away from settlements. Ultrafine particles are also the most dangerous form of particle pollution, according to experts at the National Institute of Public Health, because from the air we breathe they get directly into the bloodstream through the lungs. Several scientific studies confirm that ultrafine particles can pass through the placenta into the fetus.

Tar ingredients

Tar components (PAHs: polycyclic aromatic hydrocarbons) are organic compounds containing polycyclic aromatic rings. Of particular concern is the Benz-a-pyrene component, which is carcinogenic even in very small quantities. In residential areas with high wood-burning density, concentrations of tar compounds are higher than along the busiest roads in large cities. In wood smoke, tar constituents are present both as adherent solid particles and as gases. In the atmosphere, tar constituents increase their toxicity by adhering to the surface of particles.

Dioxins

Dioxins, which contain several chlorine atoms, are among the most dangerous organic compounds. They are carcinogenic and can damage the endocrine, reproductive and immune systems. In addition, when they accumulate in the food chain, they cause significant damage to the environment and increase the number of dioxins entering the human body through food.

Odor

Odor is caused by organic compounds in smoke from incomplete combustion, together with tar components and dioxins. There is no clear definition of odor, as tolerance is largely individual. The odor is primarily a simple aesthetic problem and is not dangerous in itself, but it can be a clear indication that wood smoke is present in the air in dangerous concentrations.

Benz-a-pyrene

A polycyclic aromatic compound, that is carcinogenic even at low concentrations! It forms at lower temperatures during incomplete combustion (e.g. when burning wood with too high moisture content).

Coal and lignite combustion

The main air pollutants are the same as those listed for wood combustion. However, there are additional pollutants to be considered for coal combustion, which are detailed in a separate article. Heavy metal ions (even radioactive ones) are often accumulated in coal, which were originally bound in plants, and then the carbonisation process favoured their accumulation.

Sulphur dioxide

Domestic carbon sources contain a lot of sulphur. The official sulphur content of Matra lignite is 1.4-2.2%, but some measurements indicate that it can even exceed 7%. Putnok coal (lignite), which is also sold in large quantities, is used in stoves and boilers with an even higher sulphur content of 4.88%. Sulphur dioxide is a colourless, pungent-smelling toxic gas that forms sulphurous acid or sulphuric acid with the moisture in the air, resulting in acid rain. Prolonged inhalation of sulphur dioxide leads to asthma. At higher levels, it can cause coughing, dyspnoea, spasms, pulmonary oedema, confusion and death.

Mercury

Mercury is cellular and neurotoxin, that inhibits certain enzymes and accumulates in the human body. Its toxicity depends on the chemical compound in contact with the human body. The main sources of mercury in the environment are coal combustion, metallurgy, municipal, hazardous and hospital waste incineration, as well as dental practices, but the mercury content of energy-saving light bulbs also poses risks. Mercury is particularly harmful to babies and children, causing learning disabilities or even severe neurological damage and developmental disorders. Chronic effects of mercury pollution can include impaired concentration and memory, depression, visual impairment, fatigue, irritability, agitation, tremors, skin disorders, dizziness, speech disorders, asthma, immune deficiency, joint and back pain.

Cadmium

In addition to natural sources, sources of cadmium in the environment include the combustion of fossil fuels, phosphate fertilisers, the manufacture of iron, steel, and other metals, the incineration of municipal waste, and cement production. The most dangerous exposure is the inhalation of fumes or dust from welding or smelting metal containing cadmium. Cadmium and most of its compounds are classified as carcinogens by all international organisations. It is toxic to the kidneys, liver, bones, and testicles and also disrupts the hormonal, immune, cardiovascular, and cardiovascular systems. Cadmium, when incorporated in place of essential zinc, causes serious damage. It also accumulates in the human and animal body, becoming chronically toxic.

Arsenic

Arsenic can be present in coal at levels of 10-1000 mg/kg, but concentrations of 8000 mg/kg have been measured in coal ash. Arsenic is mainly ingested through food and drinking water. Arsenic is a potent poison, with an estimated lethal dose in humans of 100-300 mg, although individual sensitivity varies widely. It can be absorbed in 3 ways: through the skin, lungs, and gastrointestinal tract. Inhalation causes coughing, sore throat, shortness of breath, weakness, while contact with skin and eyes causes redness and irritation. Ingestion of low concentrations over long periods (decades) causes noticeable symptoms only after many years. These are mainly skin symptoms such as increased scarring, hyperpigmentation. Another difficulty is that the occurrence of symptoms is not only related to arsenic, as these lesions can appear anyway with increasing age. In the developing organism, the nervous system is particularly sensitive to arsenic, although data on this are mainly available from animal studies. In humans, inorganic arsenic is carcinogenic, causing skin, bladder, kidney, and lung tumours. It is also implicated in the pathogenesis of a variety of chronic non-cancerous diseases when ingested at low concentrations over long periods. Examples include lesions involving skin scarring and changes in the pigment, heart and circulatory diseases, disorders of the peripheral and central nervous systems, liver and kidney diseases, diabetes, and Addison's disease. Its effects on chromosomal abnormalities and DNA repair mechanisms have been also demonstrated.

Fetal exposure to arsenic in pregnant women has also been demonstrated, with umbilical cord blood arsenic concentrations equal to those in maternal blood.

Uranium

In Hungary, the outstanding uranium content of the Ajka coal is well known. Fortunately, the mine was closed in 2004. Other coals also contain uranium but in much smaller quantities. Chemically, the metal itself and its compounds are both highly toxic.

Literature used: kockazatos.hu, legszennyezes.hu, tiszta.levego.hu