The air quality glossary, indoors and outdoors
Environment — di Rosy Battaglia
How can we assess the quality of the air we breathe inside and outside the home? Which chemical compounds should we know about? A glossary.
The air quality glossary, indoors and outdoors
How can we assess the quality of the air we breathe inside and outside the home? Which chemical compounds should we know about? A glossary.
Breathing clean air is a fundamental requirement for our lives, it is the most natural act in the world and accompanies us from birth. But have we ever wondered what we are really introducing into our bodies, inside and outside our homes? What do those 12,000 litres of air that enter and leave our lungs every day actually contain? Inhaling and exhaling at least 20,000 times over the course of 24 hours, we take in nitrogen (N) at 78 per cent, oxygen (O) at 21 per cent and argon at 1 per cent. Along with the so-called trace gases, which include carbon dioxide (CO2), which we help to produce as a result of the oxygen consumed for our vital functions.
(Almost) all the harmful substances we breathe
But many other substances in gaseous form enter our respiratory system without our knowledge. Substances present in the atmosphere that can affect our daily wellbeing. The World Health Organisation reminds us of this: those with the strongest evidence of health effects 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 (C6H6), benzo(a)pyrene (BaP), polycyclic aromatic hydrocarbons (PAHs) as well as several metals.
#WorldHealthDay focuses on "a fairer, healthier world".
#HealthforAll includes improved air quality for all
WMO supports @WHO targets to reduce air pollution deaths by two thirds by 2030
#HealthforAll includes improved air quality for all
WMO supports @WHO targets to reduce air pollution deaths by two thirds by 2030
Outdoor and indoor air quality: the glossary of key chemical, physical and biological agents
Particulate matter (PM10, PM2.5)
Both coarse and fine, it is airborne dust present in both outdoor and indoor air, produced by various sources such as soot, combustion processes and natural sources.
It is a gas composed of unstable molecules with a pungent odour. It forms from the reaction between nitrogen oxides, volatile organic compounds and solar radiation.
Nitrogen oxide and dioxide (NOx and NO2)
Typical pollutants of outdoor air, originating from vehicular traffic, they are also found in indoor air wherever gas is used, both for heating and for cooking.
These include sulphur dioxide (SO2) and sulphur trioxide (SO3). Indoors, the presence of sulphur oxides is generally due to the ingress of outdoor air.
Polycyclic aromatic hydrocarbons (PAHs)
Derived from petroleum, indoors they are emitted by kerosene boilers, wood-burning fireplaces, cigarette smoke and grilling. They contain carcinogenic agents.
It is part of the PAHs and the main source in outdoor air is petrol. Indoors it can be emitted by cigarette smoke and by glues, adhesives, solvents and paints.
It also belongs to the PAH group, produced by the incomplete combustion of petroleum derivatives. Indoors, food and air represent the main source of exposure.
It is among the pollutant gases produced by combustion — colourless, odourless, tasteless and non-irritating yet toxic: without adequate ventilation, at high concentrations, it can be fatal.
Volatile organic compounds (VOCs)
Derived from hydrocarbons, the most widespread in indoor environments are limonene, toluene and formaldehyde. They are emitted by cosmetics, deodorants, cleaning materials, glues, solvents and paints.
It belongs to the VOCs and is the most significant from a toxicological and mutagenic standpoint. It is more prevalent indoors than outdoors. It is used in resins for upholstery and furnishings.
Environmental tobacco smoke (ETS)
It remains the principal pollutant of enclosed spaces, inhaled by those in proximity to smokers. It comprises a complex of 4,000 different chemical compounds in gaseous form.
A mineral with carcinogenic fibres, banned in Italy in 1992, it is still present on the outside and inside of public and private buildings — on roofs, in floors, pipes and insulation.
Produced and spread by humans and animals in indoor environments in great variety, they include viruses, bacteria, moulds, yeasts, fungi, protozoa, algae, insects and pollens.
Dust mites are tiny Arthropod insects belonging to the class Arachnida. Their excrement contains allergens. They nest primarily in household dust.
Epidermal derivatives from domestic animals
Saliva, dander and urine from dogs and cats, but also from birds and cockroaches. Once dried and fragmented, suspended in the air within dust, they become an important source of indoor allergens.
Moulds are microscopic fungi that form as a result of humidity and poor ventilation. During their growth they produce spores that disperse into the air.
Radon is a radioactive gas found in nature as a result of the decay of uranium and thorium. It disperses rapidly in the atmosphere but concentrates in enclosed spaces.
Polluted air causes the premature death of 7 million people every year
These compounds contribute to environmental pollution and originate from the full range of human activities, from transport to industry, from heating to agriculture and livestock farming. As the World Health Organisation continually points out, polluted air, inside and outside our homes, causes at least 7 million premature deaths every year. Indeed, not even in our own homes are we safe, and the quality of the air inside houses, offices, schools, nurseries, public and private buildings and healthcare facilities is as important as that of the outdoor environment. Air quality depends on our activities and habits, on furnishings, on the structure of dwellings, on how well ventilated and how crowded they are, but also on biological contaminants, pollens and dust. As well as on which products we use to clean them.
Toxic air causes thousands of deaths a year. Here's how to prevent it wef.ch/2Y9THhW #pollution #health
We spend almost 90% of our time indoors — but this does not protect us from air pollution
All of these factors are increasingly important, especially when we consider that we spend most of our time indoors — and we were already doing so before the Covid-19 pandemic confined us to our homes during the long lockdowns. As an Ispra study on indoor pollution reported some years ago, we spend on average 84 per cent of our daily time inside enclosed spaces and at least 64 per cent at home. Figures that are rising even further, according to Casaclima, confirming that the majority of our lives — as much as 87 per cent — is spent inside buildings and at least 69 per cent in our own homes.
We too contribute to polluting the air in our homes
We cannot ignore, moreover, that we ourselves, through our activities and habits, can contribute to polluting the air in our homes and increasing the concentration of certain compounds. First of all, we must not forget that combustion processes for cooking food and heating spaces contribute to raising the concentration of the ever-present nitrogen oxide and dioxide (NOx, NO2), carbon dioxide (CO2) and the dangerous carbon monoxide (CO), as well as PAHs and fine particulate matter, both PM10 and PM2.5.
Gases and mixtures to which are added volatile organic compounds (VOCs), also known by the English acronym "VOC", standing for Volatile Organic Compounds, a category that includes formaldehyde (CH2O) and PAHs. The combustion of so-called "biomass" — driven by the growing use of wood-burning stoves and fireplaces, a phenomenon that has also increased in relation to the economic crisis and the energy policies that have encouraged their use — also adds to indoor pollution. On top of all these factors, one of the main causes of indoor pollution must be added: passive tobacco smoke (ETS), which introduces concentrations of nicotine, irritants, toxic substances and carcinogens.
The chemical, biological and physical agents that contaminate the air in our homes
And yet, none of this protects us from harmful substances. On the contrary, in our homes multiple factors converge and combine: chemical, biological and physical agents that we need to learn to recognise, prevent and avoid. Without forgetting what we all recognise: so-called "stale air", which can be caused by overcrowding, the lack of adequate ventilation and air circulation, cramped spaces, but also by the newer, better-insulated homes that prevent air from recirculating. This is why — as anti-Covid measures made us well aware — we need continuous and consistent renewal of ambient air, especially when several people are present.
This practice, however, can also mean — particularly in more polluted cities or in areas especially close to sources of vehicular traffic or industrial zones — the introduction into the domestic environment of nitrogen oxide and dioxide (NOx, NO2); sulphur oxides (SOx); carbon monoxide (CO); ozone (O3); airborne particulate matter (PM10, PM2.5); as well as benzene (C6H6), polycyclic aromatic hydrocarbons (PAHs) and asbestos fibres, all coming from outdoors.