According to the World Health Organization (WHO), nine out of ten people breathe an air that is not healthy.
Air pollution is a key environmental, economic and social issue, but also a complex problem posing multiple challenges in terms of management and mitigation of harmful pollutants.
Air pollution is an invisible killer that can affect everyone, just by walking outdoors or even in the domestic setting.
The pollutants, divided in primary and secondary toxic particles, have a wide and broad impact on health, infrastructures, environment, the ecosystem and the climate; they affect many different areas. Even though global government institutions are trying to reduce sources of pollution, it is still a worldwide problem.
Air pollution’s impact on health is a rising concern all around the world. The most hazardous pollutants are released in the air, in higher quantities than in water and soil combined [1]. Nearly 2 million premature deaths can be attributed to air pollution [2]. Almost everyone, especially populations living in large cities, is sometimes affected by respiratory irritations and breathing difficulties. Air pollution is composed of particulate matter (PM), aerosols and gases.
But it can get worse: some organic compounds in PM are notoriously known as endocrine disruptors [3] [4]. Their resemblance to the structure and shape of our hormones allows them to deceive and alter our system and causing cancers. [5].
According to WHO, about 3 billion people cook and heat their homes using open fireplaces or simple stoves in which they burn biomass (wood, animal dung, agricultural residues) and coal. More than 4 million people die prematurely from diseases caused by household air pollution from cooking with solid fuels. Also, more than half of pneumonia related deaths in children under five are due to inhalation of particulate matter from indoor air pollution. There are 3.8 million premature deaths from non-infectious and non-transmitted diseases, including strokes, ischemic heart disease, chronic obstructive pulmonary disease (COPD) and lung cancer, caused by too much exposure to air pollutants.
The latest database on urban air quality, show that 98% of cities with more than 100,000 inhabitants in low- and middle-income countries, do not comply with the WHO guidelines for air quality. Nevertheless, in high-income countries, this percentage drops to 56%. Global levels of air pollution in urban areas have increased by 8% despite improvements in some areas. Pollution of ambient air, due to high concentrations of small particles and fine particles, is the main environmental risk to health; it causes more than 3 million premature deaths each year worldwide.
SOURCE : World Health Organization
Currently, available filter systems can only capture PM, but can not reduce their toxicity. Therefore, we decided to create a cheap, compact, energy efficient, deployable on a large scale, and above all biodegradable device.
Particulate Matter
SOURCE : AirParif (Paris conglomeration Air Monitoring Administration)
Some PM are emitted directly from a source, such as industrial or domestic combustion, diesel road transport, natural origin (volcanism, erosion …). Most particles form in the atmosphere as a result of complex reactions of chemicals such as sulfur dioxide and nitrogen oxides, which are pollutants emitted from power plants, industries and automobiles. [8] Classified according to their size: - PM10: particles with a diameter of less than 10 μm (retained in the nose and upper airways) - PM2.5: particles with a diameter of less than 2.5 μm (penetrate deep into the respiratory tract to the alveoli of the lungs
Heavy metal ions (mercury, cadmium, lead ...) are for the most part soluble in water, the condensation of water is often sufficient to solubilize and recover them as witnessed by the drop in alerts of PM in Cities after a rain shower. The oxides are very hygroscopic, so they have a great affinity for water, which will allow them to be recovered in the same way. [9]
Polycyclic Aromatic Hydrocarbons (PAHs) are part of a class of organic molecules found in air with high toxicity. These molecules consisting exclusively of carbon and hydrogen come largely from combustion reactions (coal, oil, fire ...). Many PAHs are endocrine disruptors, that is, compounds that will interfere with the human hormonal system. Indeed, humans secrete hormones that will act as messenger for many functions such as growth, metabolism and production of reproductive cells. Endocrine disruptors, by their resemblance to hormones, will transmit to the body a parasitic message that will disrupt the entire system.
Composition of the Particulate Matter (PM 2.5)
Environmental impact Responsible for fouling monuments and buildings - Cost of renovation of public buildings in Ile-de-France, 1.5 to 7 billion francs per year (Source PRQA Ile-de-France), [5.] - Cost of cleaning the Louvre in 1995: around 30 million francs (Source PRQA Ile-de-France)
Health impact Irritation and alteration of respiratory functions in sensitive persons. Can be combined with toxic or even carcinogenic substances such as heavy metals and hydrocarbons, Associated with an increase in mortality due to respiratory or cardiovascular causes (ERPURS / ORS Ile-de-France). [5] [6] Small particles less than 10 micrometers in diameter can get deep into your lungs, and some may even get into your bloodstream. Exposure to such particles can affect both your lungs and your heart. Numerous scientific studies have linked particle pollution exposure to a variety of problems, including: - premature death in people with heart or lung disease - nonfatal heart attacks - irregular heartbeat - aggravated asthma - decreased lung function - increased respiratory symptoms, such as irritation of the airways, coughing or difficult breathing.
| PM 2.5 | PM 10 |
|---|---|
|
10 μg/m3 annual mean |
20 μg/m3 annual mean |
|
25 μg/m3 24-hour mean |
50 μg/m3 24-hour mean |
WHO Guideline values [14]
In addition to guideline values, the Air Quality Guidelines provide interim targets for concentrations of PM10 and PM2.5 aimed at promoting a gradual shift from high to lower concentrations.
Sources of air pollution
There are many examples of successful policies in transport, urban planning, power generation and industry sectors, which reduce air pollution due to :
Atmospheric emissions of natural origin :Forest fires, bush fires or volcanism can be the cause of natural atmospheric emissions of pollutants.
Anthropogenic emissions :Anthropogenic atmospheric emissions are emissions of human origin. Distinctions are commonly made according to the nature of the sources of emissions (mobile or fixed sources) or the sector of activity. The majority of human activities is a direct or indirect source of air pollutant emissions.
Industry Examples of pollutants emitted by this sector: sulfur dioxide (SO2), dust, metals, volatile organic compounds (VOCs). [6] Many solutions exist: clean technologies that reduce industrial smokestack emissions; improved management of urban and agricultural waste, including capture of methane gas emitted from waste sites as an alternative to incineration (for use as biogas).
Transport Road traffic accounts for more than a quarter of greenhouse gas emissions, more than half of nitrogen oxide emissions, about a quarter of PM10 and PM2.5 particulates emissions and more than 15% of emissions of hydrocarbons (VOCs). [6] All transport modes: whether it’s air transport, maritime or automobile, participate in emissions of air pollutants. Examples of pollutants emitted by this sector: oxides of nitrogen (NOx), particulates in exhaust gases, carbon monoxide (CO).
Urban planning :As for the residential and tertiary sector (mainly heating), it is the leading source of greenhouse gases (more than 40% of emissions) and weighs more than 20% in nitrogen oxide (NOx) emissions, more than a quarter of particulate matter PM10, 40% of PM2.5 and 30% of hydrocarbon emissions (COVs). [6]
Domestic activities :By using plant protection products, paints, household products, cooking ... we all emit atmospheric pollutants. Examples of pollutants emitted: volatile organic compounds.[8]
Individual and collective heating :This sector is responsible for a huge part of the emissions in temperate climate regions. The pollutants emitted are usually sulfur dioxide, carbon monoxide, nitrogen oxides or even fine particles. Air conditioning indirectly generates pollutants due to its high electricity consumption but also if the refrigerant gas is not recovered. [8]
Municipal and agricultural waste management :The agricultural sector is responsible for some of the air pollution, through the use of machinery in particular, but also because of the use of plant protection products or spreading (ammonia emission). Examples of pollutants emitted: dust, ammonia (NH3). [8]
Focus on indoor air pollution
We spend almost 80% of our time in closed spaces [10. ], whether private (apartments, houses, work, car, ...) or welcoming the public (schools, administrations, places of leisure ...). There are many internal pollutants which are the source of the cross-fertilization of our activities with the components of our environment. These sources of pollutants can be grouped into six categories [8]: - Equipment (furnishing, heat stoves, waste storage, HVAC (Heating, ventilation and air conditioning), moisture production of household appliances ...). - Human activities (DIY (Do it yourself) home improvement, cosmetics, household products, smoking, cooking ...). - Occupation of premises (animals, plants ...). - Soil (natural emanation of soils and basements). - Building and decoration materials (glue, paint varnish, insulation, coatings ...). - Outdoor air (local pollution, pesticides, pollen, dust ...). These pollutants therefore have various identities of chemical, physical and biological origin.
Impact of indoor and outdoor air pollution
On the materials :Atmospheric pollution induces corrosion due to sulfur dioxide, blackening and crusts of buildings by the dust largely resulting from the combustion of petroleum products, as well as various alterations in association with frost, moisture and micro-organisms [11].
On environment :High concentrations of some pollutants can lead to visible necrosis on plants. Air pollution can also lead to a reduction in plant growth, even without visible damage (e.g. ozone can cause a decline in agricultural production of cereals such as wheat) or reduced resistance of plants to certain infectious agents [11].
Health effects of indoor air pollution :In poorly ventilated houses, the level of fine particles contained in smoke in the domestic household can reach concentrations 100 times higher than threshold levels set by authorities. The distribution by cause of these deaths according to the WHO report is as follows [13]: - 34% of cerebrovascular accidents, which represent about 1.4 million deaths (half of them women) can be attributed to chronic exposure to pollutants released into indoor air. - 26% ischemic heart diseases; about 15% of all premature deaths per year result from exposure to polluted indoor air. - 22% Chronic Obstructive Pulmonary Disease (COPD), More than one-third of adult COPD premature deaths in low- and middle-income countries are a result of exposure to indoor air pollution. - 12% pneumonia; Exposure to indoor air pollution almost doubles the risk of pneumonia in children. (WHO, 2014). - 6% lung cancer: around 17% of premature deaths from lung cancer result, in adults, from exposure to carcinogens in domestic air. Fine particles and other pollutants in household fumes cause inflammation of the airways and lungs, degrading the immune response and reducing the oxyphoric power of the blood (WHO, 2017). In addition, it has been observed that there are links between indoor air pollution and low birth weight, tuberculosis, cataracts and cancers.
How to protect your health and our environment ?
ætherwas conceived as a biomaterial adaptable to different surfaces to capture and degrade fine particles. We did our tests on the Anthracene molecule, a member of the poly aromatic hydrocarbons (PAHs), as a proof of concept.
The main molecules that we will trap will belong to two categories: inorganic and organic. We will try to target several inorganic components in air pollution: metals (Ni, As, Pb…), their compounds, NOx, SOx, phosphates, but also organic molecules, such as anthracene, benzo[a]pyrene, all of its oxidized derivatives, that are equally toxic, including PAHs and their brominated and chlorinated derivatives (PBBs, polybrominated biphenyls, and PCBs, polychlorinated biphenyls)… The inorganic pollutants will be filtered and will stay imprisoned in our device. We plan to benefit from the added value of the metallic components, through recycling. The organic molecules will be degraded to lessen their toxicity, by enzymes. Some of these products of the degradation process can also be valorized.
Polyaromatic hydrocarbons present in polluted air constitute a major threat to the health of individuals. We have designed by synthetic biology methods a novel enzyme mix composed of four enzymes E1 :Ring hydroxylating oxygenase (1,2), E2 :Dihydrodiol dehydrogenase, E3 :2,3 Catechol dioxygenase, and E4 :trans-2-carboxybenzalpyruvate hydratase-aldolase, as a cocktail for the reaction involving anthracene degradation. Expression in Escherichia coli of the four enzymes followed by a spectrophotometric assay has allowed the observation of the degradation of anthracene. This enzyme cocktail could be used for the degradation of other multi ring aromatic compounds present in particulate matter, including benzo[a]pyrene which can hardly be modified by any other chemical methods.
REF :
[1] : http://www.conserve-energy-future.com/various-air-pollution-facts.php
[2] : https://www.airparif.asso.fr/pollution/effets-de-la-pollution-generalites
[3] : https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2677823/
[4] : https://www.ncbi.nlm.nih.gov/pubmed/27140679
[5] : https://www6.paris.inra.fr/ritme/Animations/Disrupting-pathways
[6] :airparif; https://www.airparif.asso.fr/en/index/index
[7] : https://www.transportenvironment.org/what-we-do/shipping/air-pollution-ships
[8] :Air quality in Europe — 2017 report, EEA Report No 13/2017; European Environment Agency.
[9] : WHO http://maps.who.int/airpollution/
[10] :The effects of air pollution on the environment can be felt at different geographical scales. Auteurs : R.-A. Lefèvre, Professeur émérite à l'Université Paris Est – Créteil (UPEC) et P. Ausset, Ingénieur de Recherches au Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA), 2011.
[11] : Household air pollution and health;Fact sheet N°292; Updated February 2016; WHO Media centre.
[12] : Curr Opin Cardiol. 2009 Nov;24(6):604-9. doi: 10.1097/HCO.0b013e32833161e5. Particulate air pollution and coronary heart disease. Simkhovich BZ1, Kleinman MT, Kloner RA.
[13] : http://www.who.int/sustainable-development/news-events/breath-life/infographic6-FR.jpg?ua=1
[14] :WHO Air quality guidelines for particulate matter, ozone, nitrogen dioxide and sulfur dioxide Global update 2005 Summary of risk assessment.
[15] :Ambient (outdoor) air quality and health; Fact sheet; Updated September 2016; WHO Media centre.
[16] :Respire la vie: la pollution de l'air, un tueur invisible; 20 janvier 2016.
[17] :Air quality guidelines. Global update 2005. Particulate matter, ozone, nitrogen dioxide and sulfur dioxide.
[18] :surveillance de la qualité de l’air en Île-de-france; ATMOSPHÈRE CAPITALE; airparif.
