The health impacts of air pollution result in increased hospital admissions and emergency room visits, as well as increased risk of premature death. Deaths attributed to air pollution are mainly from heart disease, stroke, chronic obstructive pulmonary disease, lung cancer, and acute lower respiratory infections in children.

While air pollution does have immediate health effects, up to and including death, most impacts of air pollution are felt over the long-term, and often are not apparent until chronic illness has developed. For this reason, air pollution is often referred to as an “invisible killer”, with lifelong impacts on health.

In children and adults, both short- and long-term exposure to ambient air pollution can lead to reduced lung function, respiratory infections and aggravated asthma.

Maternal exposure to ambient air pollution is associated with adverse birth outcomes, such as low birth weight and preterm birth. Emerging evidence also suggests ambient air pollution may affect diabetes and neurological development, As the precise death and disability toll from many of these conditions is not quantified in current estimates, the burden of disease from ambient air pollution is expected to greatly increase with growing evidence.

Worldwide, air pollution accounts for:^{10 10}‘Indicator 3.9.1: Mortality rate attributed to household and ambient air pollution (per 100 000 population), WHO Global Health Observatory’, and ‘Assessing the recent estimates of the global burden of disease for ambient air pollution: Methodological changes and implications for low- and middle-income countries. Bart Ostro et al. 2018’X

• 29% of all deaths from lung cancer
• 17% of all deaths from acute lower respiratory infection
• 24% of all deaths from stroke
• 25% of all deaths from ischaemic heart disease
• 43% of all deaths from chronic obstructive pulmonary disease

Health impacts include:

• Premature mortality;
• Adverse pregnancy outcomes such as low birth weight and stillbirths;
• Bronchitis;
• Chronic pulmonary diseases, of which 43% are as a result of air pollution;^{11 11}WHO data: Ambient air pollutionX
• Cancers;
• Cardiovascular diseases such atherosclerosis;
• Exacerbation of asthma and other allergic respiratory diseases;
• Loss of productivity and absenteeism;
• Eye conditions such as macular degeneration and cataracts;
• Skin, nose, throat and eye irritation.

Around 91% of the world’s population live in places where air pollution levels exceed WHO limits. Although air pollution affects high and low-income countries alike, low- and middle-income countries experience the greatest health burden, with the highest concentrations in 2016 seen in North Africa and the Middle East due mainly to windblown mineral dust. The next highest concentrations were observed in South Asia due to combustion emissions from multiple sources, including household use of solid fuels, coal-fired power plants, open burning, industries and transportation sector. The lowest levels of air pollution were recorded in parts of North America and Europe.^{12 12}Data Integration for the Assessment of Population Exposure to Ambient Air Pollution for Global Burden of Disease Assessment. Gavin Shaddick et al. 2018X

Exposure to smoke from cooking fires causes 3.8 million premature deaths each year, mostly in low- and middle-income countries. Household air pollution mainly impacts those in parts of the world with less access to clean fuels and technologies, including electricity.

Exposure to air pollution can affect anyone, but certain populations are especially vulnerable:

• The elderly are most susceptible to infections caused by air pollution;
• Pregnant women and Children are also susceptible to health impacts from air pollution exposure;
• People living or working in densely populated urban areas where transport and traffic is high may experience high and prolonged exposure;
• Women and girls are most affected by indoor air pollution in developing countries due to more time spent in the home;
• Those with preexisting respiratory and cardiovascular illnesses;
• Athletes and others who exercise outdoors.
• Those working in occupations with increased exposure to polluted air, such as in coal mines, are at increased risk of respiratory illnesses such as silicosis, coal workers’ pneumoconiosis and lung cancer;

Impacts of Climate Change on Air Pollution
Climate change can impact air pollutant concentrations through its effects on meteorological variables.^{13 13}Video: Connections between air quality and climate. WMO. 2021X

Many processes that produce atmospheric pollutants are temperature dependent. Enhanced temperatures accelerate ozone production,^{14 14}Stratospheric ozone depletion: the main driver of twentieth-century atmospheric circulation changes in the Southern Hemisphere. Polvani, L.M., D.W. Waugh, G.J.P. Correa, and S.W. Son, 2011X with even small increases of the pollutant expected to considerably increase the risk of premature mortality and other detrimental impacts to human health.^{15 15}Effect of climate change on air quality. Jacob, D.J. & Winner, D.A. 2009; Climate change, ambient ozone, and health in 50 US cities. Bell, M.L. et al. 2007X The interactions between higher temperatures and air pollution will also aggravate the negative health impacts of air pollution.

Weather also influences air pollutant concentrations. For example, while rainy conditions remove air pollution through wet deposition, windy conditions tend to reduce air pollution by dispersing/spreading the pollution across space. But windy conditions can also exacerbate long-range transport from distant emission sources, or exacerbate airborne dust.

Changes to atmospheric weather patterns and effects on wind direction and speed can also affect how much and how far air pollution moves. Climate change will also lead to an increasing number of high winds or stagnation with consequences for air quality.^{16 16}Video: Connections between air quality and climate. WMO. 2021X Higher periods of stagnation coupled with increased emissions of air pollution can exacerbate the intensity and duration of respiratory and cardiovascular illnesses.

In regions where temperature and precipitation patterns are projected to change due to climate change, it is likely that the frequency and severity of forest fires will also increase, releasing more air pollutants.^{17 17}WHO: Ambient air pollution: Health impactsX

Air quality is expected to decline in areas where forest fires, drought and desertification will become more common, increasing the risk of cardiovascular disease, respiratory illnesses and air-borne allergens that negatively impact human health.

Impacts of Air Pollution on Climate Change
Many of the sources of air pollution are also sources of greenhouse gas emissions, and fossil fuel burning by the energy and transport sectors is a major source of both particulate matter and carbon dioxide.

Some policies^{18 18}Air quality and climate – synergies and trade-offs. Erika von Schneidemesser and Paul S. Monks. 2013 X to reduce air pollution offer a “win–win” strategy for both climate and health: lowering the burden of disease attributable to air pollution, as well as contributing to the near- and long-term mitigation of climate change.^{19 19}WHO: Air pollutionX

Certain air pollutants, such as methane and black carbon, are also powerful short-lived climate pollutants (SLCPs) that contribute to climate change and negatively affect agricultural productivity. Although SLCPs persist in the atmosphere for short lifetimes, their global warming potential is often much greater than carbon dioxide. Black carbon, a component of particulate matter, is one of the largest contributors to global warming after CO2. Black carbon warms the earth’s atmosphere by absorbing sunlight, thereby accelerating the melting of snow and ice.

Methane, another SLCP, is a potent greenhouse gas that is 84 times more powerful than CO2, and is a precursor to ground-level ozone. Ground-level ozone and black carbon affect weather processes and decrease agricultural yields, thus threatening food security. Ground-level ozone damages plants, reducing their capability to absorb CO2 from the atmosphere.

Policies and investments supporting cleaner transport, energy-efficient housing, power generation, industry and better municipal waste management can effectively reduce key sources of ambient air pollution.

Air pollution is widespread and pollution in one region or country can contribute to declining air quality in another country. Concerted action is therefore required at multiple levels, across urban, national, regional and international scale.

Risk assessment and communications

Communicating air pollution is a complicated task. Air quality data can reflect the concentration of an individual pollutant in the form of an Air Quality Index, or combine data from multiple air pollutants in the form of an Air Quality Health Index. Health-based indices in Hong Kong and Canada express air quality in terms of health risk.

Air quality index values are also calculated and presented differently in different regions of the world, depending on the general level of pollution and the regulatory limit values set by countries. The number of pollutants included in the Index calculation can also vary, even within one country.

While communicating air quality information has a certain level of complexity, regulatory monitoring data can ensure a level of trust in the data owing to the standardized monitoring protocols as well as the rigorous data quality assurance and control requirements.

Intervention Examples

• Tracking and surveillance of polluting fuels, local air pollution levels and implementing air quality guidelines, such as the WHO air quality guidelines.

Transportation

• prioritizing rapid urban transit, walking and cycling networks in cities as well as rail interurban freight and passenger travel;
• shifting to low-emissions vehicles and fuels, including fuels with reduced sulfur content;
• implementing stricter vehicle emissions and efficiency standards.

Housing

• replacing traditional household solid fuel with lower-emission cookstoves and/or cleaner fuels;
• shifting away from kerosene;
• improving the energy efficiency of homes and commercial buildings through insulation and passive design principles such as natural ventilation and lighting;
• Reducing household air pollution through the provision of clean, affordable fuels and technologies for cooking, heating and lighting in developing countries.

Industry

• improving brick kilns and coke ovens, which emit large amounts of black carbon;
• adopting clean technologies that reduce industrial smokestack emissions;
• increased recovery and use of gas released during fossil fuel production.

Power generation

• transitioning away from fossil fuel combustion (oil, coal) for large-scale energy production, as well as diesel generators for small-scale production;
• increasing the use of low-emissions fuels and renewable combustion-free power sources (like solar, wind or hydropower);
• increasing reliance on the co-generation heat and power and distributed energy generation (e.g. mini-grids and rooftop solar power generation).

Cities

• making cities more compact, and thus energy efficient
  creating spaces for safe walking and cycling;
• investing in bus rapid transit or light rail;
• creating green spaces that help remove particulate matter and reduce the heat island effect;
• improving urban waste management, including capture of methane gas emitted from waste sites as an alternative to incineration;
• Green infrastructure such as green roofs and roadside plantings can help improve air quality. Trees and vegetation can remove harmful pollutants from the air, including ozone, nitrogen dioxide and particulate matter through deposition on leaves.

Waste management

• promoting waste reduction, waste separation, recycling and reuse or waste reprocessing;
• improving 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.

Agriculture

• reducing the burning of agricultural fields;
• promoting healthy diets low in red and processed meat and rich in plants-based foods;
• alternating wet/dry rice irrigation;
• improving the management of agricultural waste and livestock manure, including the capture of methane gas emitted from waste sites as an alternative to incineration

Air allergies occur worldwide, with millions of people affected by some form of air allergy. Ragweed is a common air allergen and is found in many countries, but is most abundant in North America and parts of central and Southern Europe. Fungal allergies are common in areas of the world that experience frequent flooding.

Air allergens, including pollens and molds, have a wide range of impacts on human health, mainly related to the respiratory system. They can exacerbate symptoms and chronic conditions in sensitized individuals. Symptoms may include:

• Skin conditions such as dermatitis and eczema;
• Allergic rhinitis, or hay fever;
• Increase risk of asthma, exacerbated symptoms and asthmatic episodes;
• Upper respiratory tract infections;;
• Conjunctivitis;
• Sleep and productivity disruption;
• Mental health impacts, such as depression

Exposure to pollen has been linked to asthma attacks and increases in hospital admissions for respiratory illness.

Air allergens, or aeroallergens, are substances carried in the air that trigger an allergic reaction. Impacts occur as microscopic pollen grains or fungal spores are inhaled or make contact with the nose, mouth, eyes and skin.

Population groups most vulnerable to the health impacts of allergens include:

• Children are particularly susceptible to most allergic diseases;
• Those with a weakened immune system can be particularly vulnerable to mold exposure;
• Those already suffering from asthma or a respiratory illness;
• Those living in poverty may lack capacity for allergy management, or live in substandard housing that may allow for mold growth and increased pollen exposure;
• Outdoor workers who face increased exposure to pollen

Increasing temperatures associated with climate are expected to increase the health impacts of air allergens. Warmer temperatures and increased CO2 concentrations favour pollen release, higher pollen counts^{24 24}Climate change and its impact on birch pollen quantities and the start of the pollen season: An example from Switzerland for the period 1969-2006. Frei & Gassner, 2008; Impacts of climate change on aeroallergens: past and future. Beggs et al 2004X and allergenicity of the released pollen.^{25 25}Genetic and environmental factors affecting the allergenicity of birch pollen. Ahlholm et al. 1998X Warmer temperatures also extend the growing season of many plants and trees so that pollen shedding occurs earlier in the spring, and for a longer period of time.^{26 26}Climate change and allergic disease. Shea et al. 2008X

Both oak and birch tree species have been shown to exhibit earlier flowering as a result of warming temperatures,^{27 27}The trend to earlier Birch pollen seasons in the UK: a biotic response to changes in weather conditions? Emberlin et al. 1997; Quercus pollen season dynamics in the Iberian Peninsula: Response to meteorological parameters and possible consequences of climate change. Garcia-Mozo et al. 2006X and in North America the ragweed pollen season has lengthened.^{28 28}Recent warming by latitude associated with increased length of ragweed pollen season in Central North America. Ziska et al 2011X The same is true for mold, with the spore season starting earlier and increasing in concentration in line with warmer temperatures.^{29 29}The long-term trends and seasonal variation of the aeroallergen Alternaria in Derby, UK. Corden & Milington 2001; The potential impacts of climate variability and change on air pollution-related health effects in the United States. Bernard et al. 2001X Air pollution associated with global climate change can also exacerbate the negative health impacts of air allergens.^{30 30}Climate change, air pollution, and allergic respiratory diseases: an update. D’Amato et al. 2016X

Extreme rainfall and rising temperatures can also contribute to a growing health impact from allergens. For example, they can cause the growth of mold indoors, which may lead to worsened respiratory conditions for people with asthma and/or mold allergies.

Remote sensing and satellite imagery is a powerful tool for monitoring air-allergens for health impact management, by providing information on the types and quantities of allergens in the air.

Local pollen data is an important way to help prevent allergic reactions, however, most data from pollen and spore monitoring networks is not freely available. The information regarding which biological particle is being monitored, where and by whom, is often not known.

Pioneering automatic monitoring has been developed, for example, in Japan, which can monitor several types of pollen simultaneously.^{31 31}Automated pollen monitoring system using laser optics for observing seasonal changes in the concentration of total airborne pollen. Kawashima et al. 2017X In France, the Observatoire de l’ambroisie is a network dedicated to monitoring ragweed pollen.

Interventions

Air-allergen forecasting enables people to better manage symptoms, however most pollen and spore networks are privately owned and the data they produce is not freely available. Pollen calendars based on forecasts can be a quick and effective way to communicate the health risks of air-allergens during seasons of high exposure.

Allergenic plant management is used effectively in some countries as a defence strategy against important allergenic plants. For ragweed and other allergenic species that readily invade habitats disturbed by humans, including wastelands, abandoned fields and road sides, the use of herbicides, mowing, competition vegetation, crop rotation, disking, graying, milling, sowing, singeing or mulching may help control plant populations. There are a number of ragweed eradication campaigns in Europe, where ragweed is invasive, that focus on correct identification of the species and subsequent control and follow-up monitoring.

Planting practices and policies consider which plant species are used in populated areas, by planting low or non-allergenic species. Species selection is also important to avoid increased air-allergen exposure from tree planting and urban reforestation.

Improvements in building design and ventilation, through the use of air conditioning, fans and dehumidifiers can be used to control mold exposure. Improved housing can include replacing leaky rooks, windows and plumbing as well as reducing outdoor sources by cleaning gutters.

Dust storms are a common meteorological hazard in arid and semi-arid regions. They are usually caused by thunderstorms, or strong pressure gradients associated with cyclones, that increase wind speed over a wide area.^{33 33}WMO: Airborne Dust: A Hazard to Human HealthX

There are frequent sand and dust storms in Northern Africa, the Middle East and Europe, the Arabian Peninsula, Central Asia, northern India, northern and north-western China, southern Mongolia and adjacent Asian countries; and in desert regions of Australia and the USA.^{34 34}WMO Airborne Dust BulletinX

These storms seriously threaten human health as well as agriculture, aviation, ground transportation, solar energy industry, air quality, infrastructure and industry, and aquatic and terrestrial ecological systems.

Dust particle size is a key determinant of potential hazard to human health. Particles larger than 10 micrometres are not breathable, and can only damage external organs – mostly causing skin and eye irritations, conjunctivitis and enhanced susceptibility to ocular infection.

Inhalable particles, those smaller than 10 micrometre, often get trapped in the nose, mouth and upper respiratory tract, thus can be associated with respiratory disorders such as asthma, tracheitis, pneumonia, allergic rhinitis and silicosis. Finer particles may penetrate the lower respiratory tract and enter the bloodstream, where they can affect all internal organs and be responsible for cardiovascular disorders.^{35 35}WMO: Airborne Dust: A Hazard to Human HealthX

Some infectious diseases can also be transmitted by dust. Meningococcal meningitis, a bacterial infection of the thin tissue layer that surrounds the brain and spinal cord, can result in brain damage and, if untreated, death in 50% of cases. Outbreaks occur worldwide, yet the highest incidence is found in the “meningitis belt”, a part of sub-Saharan Africa with an estimated population of 300 million. These outbreaks have a strong seasonal pattern – many studies have linked environmental conditions, such as low humidity and dusty conditions, to the time and place of infections.

Researchers believe that the inhalation of dust particles in hot dry weather may damage nose and throat mucosa creating favourable conditions for bacterial infection. Moreover, iron oxides embedded in dust particles may enhance the risk of infection.

Dust also plays a role in the transmission of valley fever – a potentially deadly disease – in the Southwest of the United States and in Northern Mexico, by acting as a transporter of Coccidioides fungi spores.

Other health impacts from dust include:

• Cardiovascular disease
• Respiratory problems
• Exacerbation of existing chronic health conditions, such as asthma and allergies, and chronic obstructive pulmonary disease
• Air-borne infectious diseases such as meningococcal meningitis and coccidiomycosis (valley fever)

Sand and dust primarily impact health by degrading air quality in affected regions. Fine mineral particles can be transported in dust and sandstorms and damage health when inhaled. Dust aerosol can carry irritating spores, bacteria, viruses and persistent organic pollutants. It can also irritate the lining of the respiratory tract and allow for the invasion of bacteria, such as that which causes meningococcal meningitis.

Dust storms can also cause structural damage to buildings, leading to collapse. The intense downward movement of air, known as downburst, involves vertical movement of the wind that can have devastating impacts on structures and result in many deaths.

How the climate impacts sand and dust risk
Unsustainable land management and more extreme weather events driven by climate change (especially droughts), have contributed to an increase in dust-storm activity, reducing human well-being in drylands and beyond.

How sand and dust impact the climate
Aerosols, particularly mineral dusts, impact both weather and the global and regional climate. Dust particles – especially if coated by pollution – impact the ability of clouds to absorb solar radiation, and affect the amount and location of precipitation.^{36 36}WMO: Airborne Dust: A Hazard to Human HealthX

Airborne dust functions in a manner similar to the greenhouse effect: it absorbs and scatters solar radiation entering Earth’s atmosphere, reducing the amount reaching the surface, and absorbs long-wave radiation bouncing back up from the surface, re-emitting it in all directions.

Higher intensity of sand storms and sand dune movements can also cause disruption and damage to transportation and solar and wind energy infrastructures.

Prediction of dust storms before they occur using meteorological observations is crucial for mitigating health impacts. Research forecasting products from atmospheric dust models may substantially contribute to risk reduction in many areas of societal benefit, but relies on real-time delivery of products.

The WMO Sand and Dust Storm Warning Advisory and Assessment System (SDS-WAS) has three regional nodes that provide SDS forecasts that ) enhance the ability of countries to deliver timely, quality sand and dust storm forecasts, observations, information and knowledge to users through an international partnership of research and operational communities.

Volcanic ash is a health hazard in areas with active volcanoes, and surrounding areas where the wind can transport ash – including across long distances.

Volcanic eruption ash particles can be so fine that they are breathed deep into the lungs. With high exposure, even healthy individuals can experience common short-term symptoms, including:^{39 39}USGS: Volcanic Ash Impacts & Mitigation – Respiratory Effects X

• Nasal irritation and discharge (runny nose);
• Throat irritation and sore throat, sometimes accompanied by dry coughing.’
• People with pre-existing chest complaints may develop severe bronchitic symptoms which last some days beyond exposure to ash (for example, hacking cough, production of sputum, wheezing, or shortness of breath).;
• Airway irritation for people with asthma or bronchitis; common complaints of people with asthma include shortness of breath, wheezing and coughing;
• Breathing becomes uncomfortable.

Volcanic eruptions can also cause indirect physical and mental health impacts through the displacement of persons and disruption of livelihoods, vital services, and economic activities, and destroying infrastructure.

• Fine ash particles irritate the airways and cause them to contract, making breathing more difficult in people who already have lung problems;
• Ash clouds have the potential to cause major aircraft accidents.^{40 40}WMO: Volcanic Ash Clouds and GasesX

People suffering from asthma or other lung problems such as bronchitis and emphysema, and severe heart problems are most at risk.

Asthma sufferers, especially children who may be heavily exposed to the ash when they play, may suffer bouts of coughing, tightness of the chest and wheezing. Some people who have never knowingly had asthma before may experience asthma symptoms following an ashfall, especially if they go outdoors in the ash and over-exert themselves.^{41 41} IVHHN: Health impacts of volcanic ashX

Volcanoes can impact climate change. Volcanic gases like sulfur dioxide have occasionally caused detectable global cooling of the lower atmosphere. Very large volcanic eruptions can inject significant amounts of carbon dioxide, a greenhouse gas, into the atmosphere, however it has never caused detectable global warming of the atmosphere. The 1980 eruption of Mount St. Helens vented approximately 10 million tons of CO2 into the atmosphere in only 9 hours – however it currently takes humanity only 2.5 hours to emit the same amount.^{42 42}USGS: Volcanoes Can Affect ClimateX

The magnitude of the physical and human costs from volcanoes can be reduced if adequate emergency prevention, preparedness, response and recovery measures are implemented in a sustainable and timely manner. This includes ensuring early warning systems are in place, evaluating the population, and raising awareness about the risks of volcanic activities.^{43 43}WHO: Emergencies, outbreaks & pandemics Volcanic eruptionsX

Interventions to protect people from volcanic ash include:^{44 44}IVHHN: Health impacts of volcanic ashX

• Reduce ash in your house: Keep all doors and windows closed whenever possible.
• Protection: Those undertaking clean-up operations should always wear effective dust masks. If no approved mask is available, a fabric mask improvised from cloth will filter out the larger ash particles which may contribute to throat and eye irritation. Dampening the fabric with water will improve its effectiveness. People with chronic bronchitis, emphysema or asthma are advised to stay inside and avoid unnecessary exposure to ash.
• Eye protection: In fine-ash environments, wear goggles or corrective eyeglasses instead of contact lenses to protect eyes from irritation.
• Drinking water: After light ashfall it is usually safe to drink water contaminated with ash, but it is better to filter off the ash particles before drinking. However, ash increases the chlorine requirement in disinfected surface collected water, which can be microbiologically unsafe to drink. Ash will usually make drinking water unpalatable (sour, metallic or bitter tasting) before it presents a health risk. The safest way to ensure your well-being is to stock up on water prior to the event. Collect enough drinking water for at least a week (up to one gallon , or 3-4 litres, per person per day). If you rely on collecting rainwater, cover the tank and disconnect any downpipes before ashfall occurs.
• Home-grown food: Ash-covered vegetables grown in fields are safe to eat after washing with clean water.
• Clean-up: Lightly water down the ash deposits before they are removed by shovelling, being careful not to excessively wet the deposits on roofs, which can cause excess loading and danger of collapse. Dry brushing can produce very high exposure levels and should be avoided. Hosing uses large quantities of water and may cause water shortages in heavily-populated areas.

Household use of biomass fuel for cooking and heating is widespread in Central Africa and common in South and Southeast Asia and parts of Central America.^{47 47}Proportion of population with primary reliance on clean fuels and technologies for cooking. WHO Global Health Observatory; Climate Policy Watcher: The geographical distribution of biomass burning – Methane Emissions X

The risks of biomass burning are associated with forested and grassland areas. The distribution of the fires depends strongly on weather conditions.^{48 48}GWIS: Current SituationX

Biomass burning for land management practices such as clearing of forests for agriculture, grazing or weeds control, take place over most continents but are more common over tropical savannas and tropical forest. Agricultural waste burning is also common over agricultural land in general.

Smoke from burning biomass has a range of negative health effects – from eye and respiratory tract irritation to serious disorders such as breathing problems, bronchitis, increased severity of asthma, cancer and premature death. Exposure to indoor biomass burning is particularly high among women and young children, who spend the most time near the domestic hearth in low- and middle-income countries.

3.8 million people a year die prematurely from illness attributable to the household air pollution caused by the burning of biomass, other solid fuels or kerosene for cooking. Among these 3.8 million deaths:

• 27% are due to pneumonia
• 18% from stroke
• 27% from ischaemic heart disease
• 20% from chronic obstructive pulmonary disease (COPD)
• 8% from lung cancer.

Infants, young children, women who are pregnant, and older adults are more susceptible to health impacts from smoke and ash, which are important air pollutants. Smoke and ash from wildfires can greatly impact those with pre-existing respiratory diseases or heart disease. Firefighters and emergency response workers are also greatly impacted by injuries, burns and smoke inhalation.^{49 49}WHO: WildfiresX

Recognising the need for international coordination of a diverse community dealing with the societal impacts of fires and smoke pollution, the World Meteorological Organization (WMO) Global Atmosphere Watch (GAW) Programme has taken the lead with international partners to develop and implement the VFSP-WAS.^{50 50}Vegetation Fire and Smoke Pollution Warning and Advisory System (VFSP-WAS): Concept Note and Expert Recommendations. WMO, 2018X The VFSP-WAS is an international network of research, national operational centres and users organised through regional nodes assisted by regional centres. There are two centers that provide smoke pollution forecasts: the South-East Asia VFSP-WAS center in Singapore and North America VFSP-WAS Center at Environment and Climate Change Canada.