- Air pollution is a major environmental risk to health. By reducing air pollution levels, countries can reduce the burden of disease from stroke, heart disease, lung cancer, and both chronic and acute respiratory diseases, including asthma.
- The lower the levels of air pollution, the better the cardiovascular and respiratory health of the population will be, both long- and short-term.
- The WHO Air Quality Guidelines: Global Update 2005 provide an assessment of health effects of air pollution and thresholds for health-harmful pollution levels.
- In 2016, 91% of the world population was living in places where the WHO air quality guidelines levels were not met.
- Ambient (outdoor air pollution) in both cities and rural areas was estimated to cause 4.2 million premature deaths worldwide in 2016.
- Some 91% of those premature deaths occurred in low- and middle-income countries, and the greatest number in the WHO South-East Asia and Western Pacific regions.
- Policies and investments supporting cleaner transport, energy-efficient homes, power generation, industry and better municipal waste management would reduce key sources of outdoor air pollution.
- In addition to outdoor air pollution, indoor smoke is a serious health risk for some 3 billion people who cook and heat their homes with biomass, kerosene fuels and coal.
Outdoor air pollution is a major environmental health problem affecting everyone in low, middle, and high-income countries.
Ambient (outdoor) air pollution in both cities and rural areas was estimated to cause 4.2 million premature deaths worldwide per year in 2016; this mortality is due to exposure to small particulate matter of 2.5 microns or less in diameter (PM2.5), which cause cardiovascular and respiratory disease, and cancers.
People living in low- and middle-income countries disproportionately experience the burden of outdoor air pollution with 91% (of the 4.2 million premature deaths) occurring in low- and middle-income countries, and the greatest burden in the WHO South-East Asia and Western Pacific regions. The latest burden estimates reflect the very significant role air pollution plays in cardiovascular illness and death. More and more, evidence demonstrating the linkages between ambient air pollution and the cardiovascular disease risk is becoming available, including studies from highly polluted areas.
WHO estimates that in 2016, some 58% of outdoor air pollution-related premature deaths were due to ischaemic heart disease and strokes, while 18% of deaths were due to chronic obstructive pulmonary disease and acute lower respiratory infections respectively, and 6% of deaths were due to lung cancer.
Some deaths may be attributed to more than one risk factor at the same time. For example, both smoking and ambient air pollution affect lung cancer. Some lung cancer deaths could have been averted by improving ambient air quality, or by reducing tobacco smoking.
A 2013 assessment by WHO’s International Agency for Research on Cancer (IARC) concluded that outdoor air pollution is carcinogenic to humans, with the particulate matter component of air pollution most closely associated with increased cancer incidence, especially lung cancer. An association also has been observed between outdoor air pollution and increase in cancer of the urinary tract/bladder.
Addressing all risk factors for noncommunicable diseases – including air pollution - is key to protecting public health.
Most sources of outdoor air pollution are well beyond the control of individuals and demands concerted action by local, national and regional level policy-makers working in sectors like transport, energy, waste management, urban planning, and agriculture.
There are many examples of successful policies in transport, urban planning, power generation and industry that reduce air pollution:
- for industry: 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);
- for energy: ensuring access to affordable clean household energy solutions for cooking, heating and lighting;
- for transport: shifting to clean modes of power generation; prioritizing rapid urban transit, walking and cycling networks in cities as well as rail interurban freight and passenger travel; shifting to cleaner heavy duty diesel vehicles and low-emissions vehicles and fuels, including fuels with reduced sulfur content;
- for urban planning: improving the energy efficiency of buildings and making cities more green and compact, and thus energy efficient;
- for power generation: increased use of low-emissions fuels and renewable combustion-free power sources (like solar, wind or hydropower); co-generation of heat and power; and distributed energy generation (e.g. mini-grids and rooftop solar power generation);
- for municipal and agricultural waste management: strategies for waste reduction, waste separation, recycling and reuse or waste reprocessing; as well as improved methods of biological waste management such as anaerobic waste digestion to produce biogas, are feasible, low cost alternatives to the open incineration of solid waste. Where incineration is unavoidable, then combustion technologies with strict emission controls are critical.
In addition to outdoor air pollution, indoor smoke from household air pollution is a serious health risk for some 3 billion people who cook and heat their homes with biomass fuels and coal. Some 3.8 million premature deaths were attributable to household air pollution in 2016. Almost all of the burden was in low-middle-income countries. Household air pollution is also a major source of outdoor air pollution in both urban and rural areas.
The 2005 WHO Air quality guidelines offer global guidance on thresholds and limits for key air pollutants that pose health risks. The Guidelines indicate that by reducing particulate matter (PM10) pollution from 70 to 20 micrograms per cubic metre (μg/m), we can cut air pollution-related deaths by around 15%.
The Guidelines apply worldwide and are based on expert evaluation of current scientific evidence for:
- particulate matter (PM)
- ·ozone (O3)
- ·nitrogen dioxide (NO2)
- sulfur dioxide (SO2).
Please note that the The WHO Air quality guidelines are currently under revision with an expected publication date in 2020.
Particulate matter (PM)
Definition and principal sources
PM is a common proxy indicator for air pollution. It affects more people than any other pollutant. The major components of PM are sulfate, nitrates, ammonia, sodium chloride, black carbon, mineral dust and water. It consists of a complex mixture of solid and liquid particles of organic and inorganic substances suspended in the air. While particles with a diameter of 10 microns or less, (≤ PM10) can penetrate and lodge deep inside the lungs, the even more health-damaging particles are those with a diameter of 2.5 microns or less, (≤ PM2.5). PM2.5 can penetrate the lung barrier and enter the blood system. Chronic exposure to particles contributes to the risk of developing cardiovascular and respiratory diseases, as well as of lung cancer.
Air quality measurements are typically reported in terms of daily or annual mean concentrations of PM10 particles per cubic meter of air volume (m3). Routine air quality measurements typically describe such PM concentrations in terms of micrograms per cubic meter (μg/m3). When sufficiently sensitive measurement tools are available, concentrations of fine particles (PM2.5 or smaller), are also reported.
There is a close, quantitative relationship between exposure to high concentrations of small particulates (PM10 and PM2.5) and increased mortality or morbidity, both daily and over time. Conversely, when concentrations of small and fine particulates are reduced, related mortality will also go down – presuming other factors remain the same. This allows policymakers to project the population health improvements that could be expected if particulate air pollution is reduced.
Small particulate pollution have health impacts even at very low concentrations – indeed no threshold has been identified below which no damage to health is observed. Therefore, the WHO 2005 guideline limits aimed to achieve the lowest concentrations of PM possible.
WHO Air Quality Guideline values
Particulate Matter (PM)
Fine Particulate Matter (PM2.5)
10 μg/m3 annual mean
25 μg/m3 24-hour mean
Coarse Particulate Matter (PM10)
20 μg/m3 annual mean
50 μg/m3 24-hour mean
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.
If these interim targets were to be achieved, significant reductions in risks for acute and chronic health effects from air pollution can be expected. Achieving the guideline values, however, should be the ultimate objective.
The effects of PM on health occur at levels of exposure currently being experienced by many people both in urban and rural areas and in developed and developing countries – although exposures in many fast-developing cities today are often far higher than in developed cities of comparable size.
"WHO Air Quality Guidelines" estimate that reducing annual average fine particulate matter (PM2.5) concentrations from levels of 35 μg/m3, common in many developing cities, to the WHO guideline level of 10 μg/m3, could reduce air pollution-related deaths by around 15%. However, even in the European Union, where PM concentrations in many cities do comply with Guideline levels, it is estimated that average life expectancy is 8.6 months lower than it would otherwise be, due to PM exposures from human sources.
In low- and middle- income countries, exposure to pollutants in and around homes from the household combustion of polluting fuels on open fires or traditional stoves for cooking, heating and lighting further increases the risk for air pollution-related diseases, including acute lower respiratory infections, cardiovascular disease, chronic obstructive pulmonary disease and lung cancer.
There are serious risks to health not only from exposure to PM, but also from exposure to ozone (O3), nitrogen dioxide (NO2) and sulfur dioxide (SO2). As with PM, concentrations are often highest largely in the urban areas of low- and middle-income countries. Ozone is a major factor in asthma morbidity and mortality, while nitrogen dioxide and sulfur dioxide also can play a role in asthma, bronchial symptoms, lung inflammation and reduced lung function.
100 μg/m3 8-hour mean
The recommended limit in the 2005 Air Quality Guidelines was reduced from the previous level of 120 µg/m3 in previous editions of the "WHO Air Quality Guidelines" based on recent conclusive associations between daily mortality and lower ozone concentrations.
Definition and principal sources
Ozone at ground level – not to be confused with the ozone layer in the upper atmosphere – is one of the major constituents of photochemical smog. It is formed by the reaction with sunlight (photochemical reaction) of pollutants such as nitrogen oxides (NOx) from vehicle and industry emissions and volatile organic compounds (VOCs) emitted by vehicles, solvents and industry. As a result, the highest levels of ozone pollution occur during periods of sunny weather.
Excessive ozone in the air can have a marked effect on human health. It can cause breathing problems, trigger asthma, reduce lung function and cause lung diseases.
Nitrogen dioxide (NO2)
40 μg/m3 annual mean
200 μg/m3 1-hour mean
The current WHO guideline value of 40 µg/m3 (annual mean) was set to protect the public from the health effects of gaseous.
Definition and principal sources
As an air pollutant, NO2 has several correlated activities. At short-term, concentrations exceeding 200 μg/m3, it is a toxic gas which causes significant inflammation of the airways.
NO2 is the main source of nitrate aerosols, which form an important fraction of PM2.5 and, in the presence of ultraviolet light, of ozone. The major sources of anthropogenic emissions of NO2 are combustion processes (heating, power generation, and engines in vehicles and ships).
Epidemiological studies have shown that symptoms of bronchitis in asthmatic children increase in association with long-term exposure to NO2. Reduced lung function growth is also linked to NO2 at concentrations currently measured (or observed) in cities of Europe and North America.
Sulfur dioxide (SO2)
20 μg/m3 24-hour mean
500 μg/m3 10-minute mean
A SO2 concentration of 500 µg/m3 should not be exceeded over average periods of 10 minutes duration. Studies indicate that a proportion of people with asthma experience changes in pulmonary function and respiratory symptoms after periods of exposure to SO2 as short as 10 minutes. Health effects are now known to be associated with much lower levels of SO2than previously believed. A greater degree of protection is needed. Although the causality of the effects of low concentrations of SO2 is still uncertain, reducing SO2 concentrations is likely to decrease exposure to co-pollutants.
Definition and principal sources
SO2 is a colourless gas with a sharp odour. It is produced from the burning of fossil fuels (coal and oil) and the smelting of mineral ores that contain sulfur. The main anthropogenic source of SO2 is the burning of sulfur-containing fossil fuels for domestic heating, power generation and motor vehicles.
SO2 can affect the respiratory system and the functions of the lungs, and causes irritation of the eyes. Inflammation of the respiratory tract causes coughing, mucus secretion, aggravation of asthma and chronic bronchitis and makes people more prone to infections of the respiratory tract. Hospital admissions for cardiac disease and mortality increase on days with higher SO2 levels. When SO2 combines with water, it forms sulfuric acid; this is the main component of acid rain which is a cause of deforestation.
WHO Member States recently adopted a resolution (2015) and a road map (2016) for an enhanced global response to the adverse health effects of air pollution.
WHO is custodial agency for 3 air pollution-related Sustainable Development Goals indicators:
- 3.9.1 Mortality from air pollution
- 7.1.2 Access to clean fuels and technologies
- 11.6.2 Air quality in cities.
WHO develops and produces air quality guidelines recommending exposure limits to key air pollutants (indoor and outdoor).
WHO creates detailed health-related assessments of different types of air pollutants, including particulates and black carbon particles, and ozone.
WHO produces evidence regarding the linkage of air pollution to specific diseases, such as cardiovascular and respiratory diseases and cancers, as well as burden of disease estimates from existing air pollution exposures, at country, regional, and global levels.
WHO develops tools such as AirQ+ for assessing the health impacts from various pollutants, but also the Health Economic Assessment Tool (HEAT) to assess walking and cycling interventions, the Green+ tool to raise importance of green space and health, the Sustainable Transport Health Assessment Tool (STHAT) and the Integrated Transport and Health Impact Modelling Tool (ITHIM).
WHO is developing a Clean Household Energy Solutions Toolkit (CHEST) to provide countries and programmes with the tools needed to create or evaluate policies that expand clean household energy access and use, which is particularly important as pollutants released in and around the household (household air pollution) contribute significantly to ambient pollution. CHEST tools include modules on needs assessment, guidance on standards and testing for household energy devices, monitoring and evaluation, and materials to empower the health sector to tackle household air pollution.
WHO assists Member States in sharing information on successful approaches, on methods of exposure assessment and monitoring of health impacts of pollution.
WHO is leading the Joint Task Force on the Health Aspects of Air Pollution within the Convention on Long-range Transboundary Air Pollution to assess the health effects of such pollution and to provide supporting documentation.
The WHO co-sponsored Pan European Programme on Transport Health and Environment (PEP), has built a model of regional, Member State, and multi-sectoral cooperation for mitigation of air pollution and other health impacts in the transport sector, as well as tools for assessing the health benefits of such mitigation measures.
Source: World Health Organization
- Uchafuzi wa hewa ni hatari kubwa ya mazingira kwa afya. Kwa kupunguza viwango vya uchafuzi wa hewa, nchi zinaweza kupunguza mzigo wa magonjwa ya kiharusi, ugonjwa wa moyo, kansa ya mapafu, na magonjwa ya kupumua ya muda mrefu na ya haraka, pamoja na pumu. Kwa hivyo, kadiri viwango vya uchafuzi wa hewa vinavyopungua, ndivyo afya ya moyo na mfumo wa kupumua ya watu itakuwa bora, kwa muda mrefu na kwa muda mfupi. WHO Air Quality Guidelines: Global Update 2005 - Utafiti wa athari za afya za uchafuzi wa hewa na mipaka ya viwango vya uchafuzi vinavyoathiri afya Mwaka 2016, asilimia 91 ya watu duniani waliishi katika maeneo ambayo viwango vya viwango vya ubora wa hewa vilivyopendekezwa na shirika la afya duniani (WHO) havikutimizwa. Uchafuzi wa hewa wa nje katika miji na vijijini ulikadiriwa kusababisha vifo vya mapema vya watu milioni 4.2 ulimwenguni kote mnamo 2016. Asilimia 91 ya vifo hivyo vya mapema vilifanyika katika nchi zenye mapato ya chini na ya kati, na idadi kubwa zaidi katika mikoa ya Asia Kusini Mashariki na Magharibi mwa Pasifiki. - Sera na uwekezaji kusaidia usafiri safi, nyumba nishati-tendaji, uzalishaji wa umeme, viwanda na usimamizi bora wa taka za manispaa kupunguza vyanzo kuu ya uchafuzi wa hewa nje. Kwa kuongezea uchafuzi wa hewa wa nje, moshi wa ndani ni hatari kubwa kwa afya ya watu bilioni 3 ambao hupika na kupasha joto nyumba zao kwa biomass, mafuta ya petroli na makaa ya mawe. Uchafuzi wa hewa nje ni tatizo kubwa la afya ya mazingira linalowaathiri watu wote katika nchi zenye mapato ya chini, ya kati, na ya juu. Uchafuzi wa hewa wa nje katika miji na maeneo ya vijijini ulikadiriwa kusababisha vifo vya mapema milioni 4.2 ulimwenguni kote kwa mwaka katika 2016; vifo hivi ni kwa sababu ya kuambukizwa kwa chembe ndogo za PM2.5 ambazo husababisha ugonjwa wa moyo na mfumo wa kupumua na saratani. Watu wanaoishi katika nchi zenye mapato ya chini na ya kati wanakabiliwa na mzigo wa uchafuzi wa hewa wa nje, na 91% (ya vifo vya mapema milioni 4.2) hutokea katika nchi zenye mapato ya chini na ya kati, na mzigo mkubwa zaidi katika mikoa ya WHO ya Asia Kusini Mashariki na Pasifiki Magharibi. Makadirio ya hivi karibuni ya mzigo yanaonyesha jukumu muhimu sana la uchafuzi wa hewa katika ugonjwa wa moyo na kifo. """Uhakika unaoonyesha uhusiano kati ya uchafuzi wa hewa na hatari ya ugonjwa wa moyo unapatikana zaidi na zaidi, ikiwa ni pamoja na masomo kutoka maeneo yenye uchafuzi mkubwa." WHO inakadiria kuwa katika mwaka 2016, karibu 58% ya vifo vya mapema vinavyohusiana na uchafuzi wa hewa nje ya nyumba vilitokana na ugonjwa wa moyo wa ischemic na kiharusi, wakati 18% ya vifo vilitokana na ugonjwa wa mapafu ya kudumu na maambukizo ya upumuaji wa chini, na 6% ya vifo vilitokana na saratani ya mapafu. Baadhi ya vifo vyaweza kusababishwa na sababu zaidi ya moja ya hatari kwa wakati mmoja. Kwa mfano, uvutaji sigareti na uchafuzi wa hewa huathiri kansa ya mapafu. Baadhi ya vifo vya kansa ya mapafu vingeweza kuepukwa kwa kuboresha ubora wa hewa, au kwa kupunguza uvutaji wa tumbaku. Uchunguzi wa mwaka 2013 uliofanywa na Shirika la Kimataifa la Utafiti wa Saratani (IARC) uligundua kuwa uchafuzi wa hewa wa nje ni kansa kwa wanadamu, na sehemu ya uchafuzi wa hewa ya chembechembe inahusiana sana na ongezeko la saratani, haswa kansa ya mapafu. Ushirikiano pia umeonekana kati ya uchafuzi wa hewa wa nje na ongezeko la kansa ya njia ya mkojo/kibofu cha mkojo. Kushughulikia mambo yote ya hatari ya magonjwa yasiyoambukiza - ikiwa ni pamoja na uchafuzi wa hewa - ni muhimu kulinda afya ya umma. Vyanzo vingi vya uchafuzi wa hewa nje ya nyumba ni mbali zaidi ya udhibiti wa watu binafsi na inahitaji hatua ya pamoja na watengenezaji wa sera katika ngazi za mitaa, kitaifa na kikanda kufanya kazi katika sekta kama vile usafiri, nishati, usimamizi wa taka, mipango ya mijini na kilimo. """Kuna mifano mingi ya sera za mafanikio katika usafiri, mipango ya mijini, uzalishaji wa umeme na viwanda ambazo hupunguza uchafuzi wa hewa: kwa viwanda: teknolojia safi ambazo hupunguza uzalishaji wa moshi wa viwanda; kuboresha usimamizi wa taka za mijini na za kilimo, ikiwa ni pamoja na kuhifadhi gesi ya methane iliyotolewa kutoka kwa maeneo ya taka kama mbadala wa kuchoma (kwa matumizi ya biogas); kwa usafiri: kuhakikisha upatikanaji wa ufumbuzi wa nishati safi kwa ajili ya vyumba vya chakula, joto na taa; kwa hivyo: kuongezeka kwa matumizi ya nishati mbadala (kama vile umeme wa maji, umeme wa hewa, na umeme wa umeme) """ Kwa ajili ya usimamizi wa taka za manispaa na kilimo: mikakati ya kupunguza taka, kutenganisha taka, kuchakata na kutumia tena au kuchakata tena taka, pamoja na mbinu zilizoboreshwa za usimamizi wa taka za kibiolojia kama vile kumeng'enya taka za anaerobic kutengeneza biogas, ni mbadala zinazowezekana, za gharama nafuu kwa kuchoma wazi taka ngumu. Ambapo kuchoma ni lazima, basi teknolojia ya kuchoma na udhibiti mkali wa uzalishaji ni muhimu. Kwa kuongezea uchafuzi wa hewa wa nje, moshi wa ndani kutoka kwa uchafuzi wa hewa wa nyumbani ni hatari kubwa ya afya kwa watu bilioni 3 ambao hupika na kupasha joto nyumba zao kwa mafuta ya biomass na makaa ya mawe. Takriban vifo vya mapema milioni 3.8 vilitokana na uchafuzi wa hewa wa nyumbani mnamo 2016. Karibu mzigo wote ulikuwa katika nchi zenye mapato ya kati na ya chini. Uchafuzi wa hewa wa nyumbani pia ni chanzo kikuu cha uchafuzi wa hewa wa nje katika maeneo ya mijini na vijijini. Miongozo ya ubora wa hewa ya WHO ya 2005 inatoa mwongozo wa kimataifa juu ya mipaka na mipaka ya uchafuzi wa hewa muhimu ambao una hatari kwa afya. Miongozo hiyo inaonyesha kuwa kwa kupunguza uchafuzi wa PM10 kutoka 70 hadi 20 mg kwa mita ya kiunzi, tunaweza kupunguza vifo vinavyohusiana na uchafuzi wa hewa kwa karibu 15%. Miongozo hii inatumika ulimwenguni kote na inategemea tathmini ya wataalamu ya ushahidi wa kisayansi wa sasa kwa: - chembechembe (PM) - ozone (O3) - nitrojeni dioksidi (NO2) - sulfuri dioksidi (SO2). Miongozo ya WHO ya ubora wa hewa inasafishwa na tarehe ya kuchapishwa inatarajiwa mnamo 2020. PM (Particulate Matter) ni kiwango cha juu cha uchafuzi wa hewa. Inaathiri watu wengi kuliko uchafuzi mwingine wowote. Vipengele vikuu vya PM ni sulfate, nitrates, amonia, sodium chloride, kaboni nyeusi, vumbi la madini na maji. Ni mchanganyiko tata wa chembe ngumu na za kioevu za vitu vya kikaboni na visivyo vya kikaboni vilivyochukuliwa hewani. Chembe zenye kipenyo cha microns 10 au chini (PM10 au chini) zinaweza kupenya na kukaa ndani ya mapafu, lakini chembe zenye kipenyo cha microns 2.5 au chini (PM5) ni hatari zaidi kwa afya. PM2.5 inaweza kuvunja kizuizi cha mapafu na kuingia kwenye mfumo wa damu. Kuathiriwa kwa muda mrefu na chembechembe huongeza hatari ya kupatwa na magonjwa ya moyo na ya mfumo wa kupumua, na vilevile kansa ya mapafu. Kwa kawaida, vipimo vya ubora wa hewa vinaripotiwa kwa viwango vya wastani wa kila siku au cha kila mwaka vya chembechembe za PM10 kwa mita ya kiunzi ya kiasi cha hewa (m3). Kwa kawaida, vipimo vya kawaida vya ubora wa hewa huelezea viwango hivyo vya PM katika micrograms kwa mita ya kiunzi (μg m3). Kwa mfano, kwa mfano, kwa mfano, kwa mfano, kwa mfano, kwa mfano, kwa mfano, kwa mfano, kwa mfano, kwa mfano, kwa mfano, kwa mfano, kwa mfano, kwa mfano, kwa mfano, kwa mfano, kwa mfano, kwa mfano, kwa mfano. Kuna uhusiano wa karibu kati ya kuambukizwa kwa viwango vya juu vya chembe ndogo (PM10 na PM2.5) na kuongezeka kwa vifo au ugonjwa, kila siku na kwa muda. Kinyume chake, wakati mkusanyiko wa chembe ndogo na nzuri hupunguzwa, vifo vinavyohusiana pia vitashuka <unk> ikidhani sababu nyingine zinabaki sawa. Hii inaruhusu watunga sera kutabiri maboresho ya afya ya idadi ya watu ambayo yanaweza kutarajiwa ikiwa uchafuzi wa hewa wa chembe ndogo hupunguzwa. uchafuzi ndogo chembe kuwa na athari za afya hata katika mkusanyiko mdogo sana <unk> kwa kweli hakuna kizingiti imekuwa kutambuliwa chini ambayo hakuna madhara kwa afya ni aliona. Kwa hivyo, viwango vya miongozo ya WHO ya 2005 vilikusudiwa kufikia viwango vya chini zaidi vya PM. WHO inaonyesha viwango vya kiwango cha juu cha PM2.5 (pamoja na kiwango cha juu cha PM10 na PM2.5), na viwango vya juu vya PM10 (pamoja na kiwango cha juu cha PM10 na PM2.5), na viwango vya juu vya PM10 na PM2.5 (pamoja na kiwango cha juu cha PM10 na PM2.5). Ikiwa malengo haya ya muda yatatimizwa, kupunguza kwa kiasi kikubwa kwa hatari za athari za afya za haraka na za muda mrefu kutoka kwa uchafuzi wa hewa inaweza kutarajiwa. Hata hivyo, kufikia maadili ya miongozo inapaswa kuwa lengo la mwisho. Athari za PM kwenye afya hutokea katika viwango vya mfiduo ambavyo kwa sasa vinapatikana na watu wengi katika maeneo ya mijini na vijijini na katika nchi zilizoendelea na zinazoendelea - ingawa mfiduo katika miji mingi inayoendelea haraka leo mara nyingi ni kubwa zaidi kuliko katika miji iliyoendelea ya ukubwa sawa. "Miongozo ya ubora wa hewa ya WHO inakadiria kwamba kupunguza wastani wa kila mwaka wa kiasi cha chembechembe (PM2.5) kutoka viwango vya 35 mg kwa m3 (kila moja) hadi kiwango cha miongozo ya WHO ya 10 mg kwa m3 inaweza kupunguza vifo vinavyohusiana na uchafuzi wa hewa kwa karibu 15%.""" Hata hivyo, hata katika Umoja wa Ulaya, ambapo viwango vya PM katika miji mingi hufuata viwango vya Mwongozo, inakadiriwa kuwa wastani wa maisha ni miezi 8.6 chini ya ingekuwa vinginevyo, kutokana na mfiduo wa PM kutoka kwa vyanzo vya binadamu. Katika nchi zenye mapato ya chini na ya kati, kuambukizwa kwa uchafuzi ndani na karibu na nyumba kutoka kwa kuchoma kwa mafuta ya uchafuzi kwenye moto wa wazi au jiko la jadi la kupikia, joto na taa huongeza hatari ya magonjwa yanayohusiana na uchafuzi wa hewa, ikiwa ni pamoja na maambukizo ya upumuaji wa chini, ugonjwa wa moyo, ugonjwa wa mapafu ya muda mrefu na kansa ya mapafu. Ugonjwa wa ugonjwa wa kisukari unaathiri afya ya binadamu kutokana na athari za kemikali za PM, ozoni (O3), nitrojeni dioksidi (NO2) na sulfuri dioksidi (SO2). Kama ilivyo na PM, mkusanyiko ni mara nyingi juu zaidi katika maeneo ya mijini ya nchi za mapato ya chini na ya kati. Ozoni ni sababu kuu ya ugonjwa wa pumu na vifo, wakati nitrojeni dioksidi na sulfuri dioksidi pia inaweza kucheza jukumu katika pumu, dalili za bronchial, uvimbe wa mapafu na kupunguza kazi ya mapafu. "Mipaka iliyopendekezwa katika Miongozo ya Ubora wa Hewa ya 2005 ilipunguzwa kutoka kiwango cha awali cha 120 mg m3 katika matoleo ya awali ya ""Miongozo ya Ubora wa Hewa ya WHO"" kulingana na uhusiano wa hivi karibuni kati ya vifo vya kila siku na viwango vya chini vya ozoni." Ufafanuzi na vyanzo kuu Ozoni katika ngazi ya ardhi - si kuchanganyikiwa na tabaka la ozoni katika anga ya juu - ni moja ya vipengele kuu ya smog photochemical. Ni inayotokana na athari na mwanga wa jua (photochemical reaction) ya uchafuzi kama vile oksidi nitrojeni (NOx) kutoka magari na uzalishaji wa viwanda na kemikali za kikaboni (VOCs) zinazotokana na magari, solvents na viwanda. Kwa sababu hiyo, kiwango cha juu zaidi cha uchafuzi wa ozoni hutokea wakati wa hali ya hewa yenye jua. Ozon nyingi sana katika hewa yaweza kuwa na athari kubwa kwa afya ya binadamu. Inaweza kusababisha matatizo ya kupumua, kusababisha pumu, kupunguza kazi ya mapafu na kusababisha magonjwa ya mapafu. Nitrogen dioksidi (NO2) 40 mg m3 wastani wa kila mwaka 200 mg m3 wastani wa saa moja kiwango cha miongozo ya sasa ya WHO ya 40 mg m3 (kiwango cha kila mwaka) iliwekwa kulinda umma kutoka kwa athari za afya za gesi. Kwa sababu ya hali ya hewa, NO2 ina shughuli kadhaa zinazohusiana. Katika viwango vya juu kama 200 mg m3, ni sumu ambayo husababisha uvimbe mkubwa wa njia za hewa. Nitrate aerosols ni chanzo kikuu cha nitrate aerosols, ambayo huunda sehemu muhimu ya PM2.5 na, kwa uwepo wa mwanga wa ultraviolet, ozone. Vyanzo vikuu vya uzalishaji wa binadamu wa NO2 ni michakato ya kuchoma (kupasha joto, uzalishaji wa umeme, na injini katika magari na meli). Uchunguzi wa magonjwa ya magonjwa ya akili umeonyesha kuwa dalili za bronchitis kwa watoto wenye pumu huongezeka kwa kushirikiana na mfiduo wa muda mrefu wa NO2. Ukosefu wa utendaji wa mapafu pia unahusishwa na NO2 katika viwango vya sasa vilivyopimwa (au vilivyoonekana) katika miji ya Ulaya na Amerika Kaskazini. Sulfur dioxide (SO2) - 20 mg m3 - wastani wa masaa 24 - 500 mg m3 - wastani wa dakika 10 - kiwango cha SO2 cha 500 mg m3 haipaswi kuzidiwa kwa vipindi vya wastani vya dakika 10. Utafiti unaonyesha kwamba idadi ya watu wenye pumu wanapata mabadiliko katika utendaji wa mapafu na dalili za kupumua baada ya vipindi vya kuambukizwa SO2 kwa muda mfupi kama dakika 10. Kwa sasa, athari za afya zinajulikana kuhusishwa na viwango vya chini zaidi vya SO2 kuliko vile vilivyoaminika hapo awali. Kiwango kikubwa zaidi cha ulinzi kinahitajika. Ingawa sababu ya athari za viwango vya chini vya SO2 bado haijulikani, kupunguza viwango vya SO2 kunaweza kupunguza mfiduo wa uchafuzi wa mazingira. SO2 ni gesi isiyo na rangi na harufu kali. Inatokana na kuchoma mafuta ya makaa ya mawe (makaa ya mawe na mafuta) na kuyeyuka kwa madini ya madini yenye sulfuri. Chanzo kikuu cha SO2 ni kuchoma mafuta ya makaa ya mawe yenye sulfuri kwa ajili ya joto la nyumbani, uzalishaji wa umeme na magari. SO2 inaweza kuathiri mfumo wa kupumua na kazi za mapafu, na kusababisha kuchochea macho. Uvimbe wa njia za kupumua husababisha kikohozi, kutokwa kwa mucus, kuongezeka kwa pumu na bronchitis ya muda mrefu na hufanya watu kuwa na uwezekano mkubwa wa maambukizi ya njia za kupumua. Ugonjwa wa moyo na vifo huongezeka siku zenye viwango vya juu vya SO2. SO2 inapoungana na maji, huunda asidi sulfuriki, ambayo ni sehemu kuu ya mvua ya asidi ambayo husababisha ukataji miti. WHO imeidhinisha azimio la mwaka 2015 na ramani ya barabara ya mwaka 2016 kwa ajili ya kukabiliana na athari mbaya za uchafuzi wa hewa. WHO ni shirika la ulinzi kwa ajili ya viashiria vitatu vya malengo ya maendeleo endelevu yanayohusiana na uchafuzi wa hewa: 3.9.1 Kifo kutokana na uchafuzi wa hewa; 7.1.2 Upatikanaji wa mafuta safi na teknolojia; 11.6.2 Ubora wa hewa katika miji. WHO inaandaa na kutoa miongozo ya ubora wa hewa inayopendekeza mipaka ya mfiduo wa uchafuzi wa hewa muhimu (ndani na nje). WHO inatoa tathmini za kina za afya za aina tofauti za uchafuzi wa hewa, ikiwa ni pamoja na chembechembe na chembechembe nyeusi za kaboni na ozoni. WHO inatoa ushahidi kuhusu uhusiano wa uchafuzi wa hewa na magonjwa maalum, kama vile magonjwa ya moyo na mishipa ya kupumua na saratani, na pia makadirio ya mzigo wa magonjwa kutoka kwa maambukizi ya uchafuzi wa hewa, katika ngazi za nchi, mkoa na kimataifa. WHO inaendeleza zana kama vile AirQ+ kwa ajili ya kutathmini athari za afya kutoka kwa uchafuzi mbalimbali, lakini pia Health Economic Assessment Tool (HEAT) kwa ajili ya kutathmini hatua za kutembea na baiskeli, Green + chombo kwa ajili ya kuongeza umuhimu wa nafasi ya kijani na afya, Sustainable Transport Health Assessment Tool (STHAT) na Integrated Transport and Health Impact Modelling Tool (ITHIM). WHO inaendeleza Kitengo cha Vifaa vya Suluhisho la Nishati safi ya Nyumba (CHEST) ili kutoa nchi na programu na zana zinazohitajika kuunda au kutathmini sera ambazo zinaongeza upatikanaji wa nishati safi ya nyumba na matumizi, ambayo ni muhimu hasa kwa sababu uchafuzi wa mazingira unaotolewa ndani na karibu na nyumba (chafu ya hewa ya nyumba) huchangia sana uchafuzi wa mazingira. Vifaa vya CHEST ni pamoja na moduli juu ya tathmini ya mahitaji, mwongozo juu ya viwango na upimaji wa vifaa vya nishati vya nyumbani, ufuatiliaji na tathmini, na vifaa vya kuwezesha sekta ya afya kukabiliana na uchafuzi wa hewa wa nyumbani. WHO inasaidia nchi wanachama kushiriki habari juu ya mbinu za mafanikio, juu ya mbinu za tathmini ya mfiduo na ufuatiliaji wa athari za afya za uchafuzi. WHO inaongoza Kikundi cha Kazi cha Pamoja cha Masuala ya Afya ya Uchafuzi wa Hewa ndani ya Mkataba wa Uchafuzi wa Hewa wa Mbali wa Mpaka wa Mipaka ili kutathmini athari za afya za uchafuzi huo na kutoa nyaraka za kuunga mkono. Programu ya Pan-Ulaya ya Usafiri, Afya na Mazingira (PEP) iliyofadhiliwa na WHO, imeunda mfano wa ushirikiano wa kikanda, wa nchi wanachama, na wa sekta nyingi kwa kupunguza uchafuzi wa hewa na athari zingine za afya katika sekta ya usafiri, na zana za kutathmini faida za afya za hatua hizo za kupunguza. Chanzo: Shirika la Afya Ulimwenguni