Air pollution, what we breathe every day
Environment — di Rosy Battaglia
What do we breathe every day? Which substances? What damage do they cause to our health? We took stock of air pollution.
Air pollution, what we breathe every day
What do we breathe every day? Which substances? What damage do they cause to our health? We took stock of air pollution.
Air pollution, outdoors and indoors
Air pollution, inside and outside our homes, makes the air we breathe persistently toxic. Human activities — from transport to heating, as well as smoking, cooking using fossil fuel combustion, and wildfires — affect the quality of the atmosphere and what we absorb through our respiratory tracts. Getting to know pollutants and understanding the mechanisms that produce them can raise awareness among citizens and consumers, and help to change — and improve — the quality of our lives.
Not just air…
Let us start with the composition of the atmosphere that surrounds us: ideally it should be made up of nitrogen (N) at 78 per cent, oxygen (O) at 21 per cent, and one per cent argon. In addition to water vapour, the air also contains very small quantities of other gases, the so-called trace gases, including carbon dioxide (CO2) and methane (CH4). The concentrations of these minor gases in the atmosphere are usually measured in parts per million (ppm). All of this, ideally. In reality, today, alongside them we breathe in gases and pollutants produced by human activities. Those with the strongest evidence of health effects, according to the World Health Organisation, are particulate matter (PM), ozone (O3), nitrogen dioxide (NO2), sulphur dioxide (SO2) and carbon monoxide (CO). With certain negative consequences following short- or long-term exposure. To these substances we must then add benzene, benzo(a)pyrene and PAHs — polycyclic aromatic hydrocarbons — and metals.
Fine particulate matter, the most dangerous for health
According to the European Environment Agency, particulate matter is the air pollutant that causes the greatest harm to human health in Europe. Classified as a Group 1 carcinogen by the Iarc, it consists of inhalable and respirable particles in the most varied combinations, such as sulphate, nitrates, ammonia, sodium chloride, soot or black carbon, mineral dust and water.
Particles with a diameter of less than 10 microns (PM10) and fine particles of less than 2.5 microns (PM2.5) pose the greatest health risks, as they are able to penetrate our lungs and enter the bloodstream. This makes it a very different pollutant from all others, presenting itself not as a specific chemical entity but as a mixture of particles with the most varied properties. What produces it? The main emission sources of particulate matter are combustion engines (both diesel and petrol), but also plants powered by solid fuels (such as coal, lignite, heavy oil and biomass). Both for energy production in households and industry, and for other industrial activities (construction, mining, cement production and waste incineration).
Ozone should be 25 km up in the atmosphere, but instead…
Ozone (O3) is a pale blue gas with a characteristic pungent smell, unstable and toxic to living things. Its place should be in the upper layers of the atmosphere, at an average height of 25 km. But it is produced at ground level when, as a result of pollution, carbon monoxide (CO), methane or other volatile organic compounds are oxidised — that is, they react on contact with the oxygen in nitrogen oxides (NOx) and sunlight, particularly in summer. The result is that tropospheric ozone, produced by this chemical reaction, ends up in the gaseous mixture we breathe, and is one of the main components of photochemical smog, which forms from the combination of solar radiation and certain pollutants. The resulting mix is harmful to health: it can promote asthma, reduced lung function and respiratory diseases, and is also a short-lived climate pollutant and one of the most important greenhouse gases.
The danger of NOx, the nitrogen oxides produced by all combustion processes
Nitrogen dioxide (NO2) is a reddish-brown gas with a strong, pungent smell, highly toxic and irritating. Being denser than air, it tends to remain at ground level. In general, all nitrogen oxides (NOx) are produced by all high-temperature combustion processes (heating systems, vehicle engines, industrial combustion, power plants, etc.), through the oxidation of atmospheric nitrogen.
Nitrogen dioxide in turn promotes the formation of particulate matter and ozone. Also according to the WHO, it causes respiratory problems and infections such as bronchitis and asthma, and reduces lung function and growth. Exposure to it is linked to premature mortality and increased morbidity — that is, the percentage frequency of cardiovascular and respiratory diseases in the exposed population.
The reason for acid rain: sulphur dioxide
Sulphur dioxide (SO2), formerly known as sulphurous anhydride, is a colourless gas with a pungent, irritating smell that is highly soluble in water. In the presence of water or water vapour it can attack many metals, including aluminium, iron, steel, brass, copper and nickel. In liquefied form, it can corrode plastics and rubber. Its presence in the atmosphere is due above all to the combustion of fossil fuels (coal and petroleum derivatives) in which sulphur is present as an impurity. The main anthropogenic sources are heating and energy production plants powered by diesel, coal and fuel oils. In nature, it is produced mainly by volcanic activity.
Exposure to SO2 affects the respiratory system and lung function and causes eye irritation. Inflammation of the respiratory tract from SO2 can worsen asthma and chronic bronchitis, and increases the risk of infection, leading to a rise in hospital admissions and emergency department visits. SO2 also combines with water in the air to form sulphuric acid, the main component of acid rain.
The most dangerous in an enclosed space: carbon monoxide
Carbon monoxide (CO), on the other hand, is a colourless and odourless gas that at high levels can be harmful to humans, compromising the amount of oxygen carried in the bloodstream to critical organs. This makes it very dangerous at high concentrations, to the point of causing death, inside a home. But even long-term exposure at low concentrations is associated with a wide range of health effects. The main environmental sources of CO include exhaust gases from motor vehicles and machinery burning fossil fuels. In the home environment, stoves, boilers and fireplaces, in the absence of ventilation.
Benzene, polycyclic aromatic hydrocarbons and metals are carcinogenic
Other pollutants, highly hazardous and carcinogenic, come from industrial processes, from oil refining processes and from exhaust gases. These include benzene, polycyclic aromatic hydrocarbons, through to metals such as arsenic, cadmium, chromium, mercury, nickel and lead.
CO2 is not poisonous to us, but it is to the planet
Against all fake news, clarification is needed. CO2 is not toxic, it is not harmful to humans: it is a "natural" atmospheric compound. We generate it through respiration. It is produced during the combustion or decomposition of organic molecules. It contributes to the Earth's natural thermoregulation. But, as is well known, its excess, due to anthropogenic activities, is accelerating the rate of global warming.
Where to consult air quality data
Knowing where to consult the public databases that make data on the air in our cities available on a daily basis is very important. The World Health Organisation has even produced a global map of air pollution, "Global ambient air pollution", based on its own guidelines for individual pollutants. The European Environment Agency has made available its own data collection and visualisation system with the European Air Quality Index. A useful tool for understanding, at a glance, how the air is in our regions and cities and for comparing ourselves with other European realities.
A sore point: the "air quality index" (AQI), the indicator that provides an immediate, summary assessment of the state of the air, is not uniform across all countries. As a result, both in Italy (from region to region) and across Europe, different formulations have been developed. Based, for example, on measured, estimated or forecast concentrations of pollutants; on whether these are hourly or daily figures; and on the varying number of pollutants with health effects. A system that will certainly need to be improved, precisely in order to make such information more comprehensible to citizens.
Regional maps on air quality in Italy
Data relating to Italy are not currently viewable in a single national database, neither on the website of the Ministry of the Environment nor on that of Ispra, the Istituto superiore per la Ricerca ambientale, the scientific and regulatory body responsible for collecting and processing environmental data from the regions. However, thanks to the 2016 law that established the national environmental protection system, it is now possible to find, on a single page, all the data processed by the regions. Environmental monitoring by the individual regional environmental agencies (Arpa) is carried out through control stations for the various pollutants, positioned in every municipality or city. Arpa collects the data on dedicated platforms that must be searched and consulted, where information on what we breathe, recorded daily, can be found. A vast body of work available to policymakers and the public, for new and possible air policies.
Civic monitoring and citizen science for cleaner air
In some parts of our country, however, it has been civil society that has mobilised to press institutions for greater controls. Citizens, scientists, epidemiologists, data scientists and associations. With citizen science campaigns, using crowdfunding to purchase new air monitoring stations in areas lacking them, or engaging in air monitoring.
This is what happened in Florence with the project Che aria tira, started by the Mamme no inceneritore, which spread to several Italian cities. In Milan, thanks to the work of Cittadini per l'aria, there was a civic monitoring project against NO2. In Taranto, another project sees activists from Peacelink collaborating with data scientists to create a platform, drawing on open environmental data from Arpa Puglia, which produces real-time measurements and shares them via Twitter. This extends all the way to the production of full-blown national reports such as the one historically produced by Legambiente, Mal'Aria. Examples of growing civic participation. Because air truly belongs to everyone and we must take care of it.
Il dossier annuale di @Legambiente sull'#inquinamento atmosferico nel 2018, "Mal'aria 2019", rileva che nelle città italiane l'#aria è irrespirabile sia d'inverno che d'estate.
#ANSAAmbiente
➡ bit.ly/2FWDWDU
#ANSAAmbiente
➡ bit.ly/2FWDWDU