Every day, Miriam pitches camp at the Muthurwa Market in Nairobi, selling tomatoes oblivious to the wafting smoke from a burning garbage heap and emissions from buses at the nearby bus stop.
She has been at it at the same spot for four years now, and gotten used to the occupational hazards.
After two years after being exposed to these pollutants every day, she developed asthma, and was put under medication to keep it under control.
Miriam is one of the people in the world whose asthma is triggered by breathing in air polluted by ozone or fine particulate matter, which enter deep into the lung’s airways and causes difficulties breathing.
According to a study published in Environmental Health Perspectives last month, nine to 23 million annual asthma emergency room visits may be triggered by ozone, a pollutant generated when car, power plant and other emissions interact with sunlight.
Five to 10 million asthma emergency room visits were linked to fine particulate matter, small particles that get lodged deep in the airways and find their way into the bloodstream.
Miriam knows nothing about the United Nation study published in May that found that Muthurwa Market, Kariokor Baba Dogo, Donholm, Hazina Estate and parts of Gachie, are among the areas with the most polluted air in Nairobi.
But she does know that the smoke is not good for her, but she has nowhere else to erect her stall in the full and segmented market.
In any case, while she sees the pollution that causes her ill health, most of the pollution people in the world are exposed to, is not visible, yet it causes major health problems.
It doesn’t just cause chronic respiratory diseases, lung cancer and lower respiratory infections, but also health problems such as heart disease, stroke, kidney disease and diabetes, which would not ordinarily be linked to air pollution, were it not for continuous research that has linked these ailments to dirty air.
According to the World Health Organisation (WHO), 91 per cent of the world’s population lives in places with unsafe air, which caused 4.1 million illnesses and 230,000 premature deaths in 2016, according to data from the Global Burden of Disease Study, which quantified the impacts of air pollution on heart disease, chronic respiratory diseases, lung cancer and lower respiratory infections.
Air pollution contains fine particulate matter, or PM2.5, which is a mixture of invisible particles, which can stay in the air longer, where humans inhale them regularly without knowing it. PM2.5 can lead to serious health effects when inhaled often, because the particles get into the bloodstream and cause inflammation and other harmful health effects.
“The situation is worsened by traffic jams that concentrate the pollution in one area. Climate change and global warming are also precipitating factors,” says UN Environment’s chief scientist Jacqueline McGlade.
The far-reaching effects of air pollution which have become clearer and more pronounced, and their link to non-communicable illnesses which have become a growing concern, prompted the global health body to hold its first conference on air pollution last week.
In Kenya, where air quality is not monitored as seriously by the authorities, it is not clear just how much pollution Kenyans are exposed to, but a global air quality database maintained by the World Health Organisation, shows that most of the country is exposed to fine particulate matter of between 16 to 25 micrograms' per cubic metre of air, with the rest exposed to fine particulate matter of between 11 to 15 micrograms' per cubic metre of air, which is above the recommended limit.
Moreover, this year’s Economic Survey showed that respiratory illnesses are the leading reasons for hospital visits.
The most prominent of these diseases include asthma, bronchitis, emphysema, laryngitis, pneumonia and influenza, and pneumonia has been the leading cause of death since 2015.
Some estimates suggest that 21,000 Kenyans die from air pollution related causes every year.
In a study published in the European Heart Journal in August, researchers from Germany, England and the US, found that particulate matter, ozone, nitrogen dioxide, carbon monoxide and sulphur dioxide damage the cardiovascular system, causing 60 per cent of the more than four million deaths from polluted air.
“When ultrafine matter is inhaled, it immediately enters the bloodstream through the lungs, is taken up by the vessels, and causes inflammation.
“Ultimately, this causes atherosclerosis, leading to heart attack (myocardial infarction), heart failure and cardiac arrhythmias,” said Professor Thomas Munzel, a cardiologist from Germany, who reviewed the mechanisms responsible for vascular damage from air pollution, with scientists from the UK and the US.
Another study published in the same journal in October, found that when people are exposed to transportation noise (from cars, trains and aircraft) in addition to air pollution, the risk of heart attack and diabetes increases.
Fine particulate matter and soot has also been associated with higher blood pressure, in combination with noise pollution.
Fine particles exceeding 12 micrograms per cubic metre of air damage the kidneys in the same way they damage the heart and lungs.
Airborne and invisible, microscopic pieces of dust, dirt, smoke, soot and liquid droplets invade the bloodstream and as the blood enters the kidney for filtration, the harmful particles disrupt normal kidney function, found a study published in September 2017, in the Journal of the American Society of Nephrology.
According to the World Health Organisation, once the pollutants get into the body, they dissolve in fats and remain in the body due to their rock-solid chemical stability, where they cause different effects.
Air is contaminated by dust, pollen, soot, smoke and liquid droplets, many of which are microscopic and can penetrate deep into the lungs with adverse effects.
Outdoor air pollution is majorly linked to cars and industrial production and burning waste.
Agriculture also causes air pollution, mainly in the form of ammonia, which enters the air as a gas from heavily fertilised fields and livestock waste. It then combines with pollutants from combustion – mainly nitrogen oxides and sulfates from vehicles, power plants and industrial processes – to create tiny solid particles no more than 2.5 micrometres.
Outdoor air pollution is compounded by global warming, as hotter temperatures speed up the chemical reactions that create air pollutants like ozone and fine particulate matter, which impact public health.
Indoor air pollution mainly arises from biomass fuels such as dung and firewood being burned for heating or cooking. While outdoor air pollution is mainly an urban problem, indoor air pollution tends to be rural.
Across the African continent, dirty air is thought to kill more people than unsafe water, malnutrition and unsafe sanitation.
So serious are the effects of air pollution, that the WHO estimates that air pollution is responsible for a third of deaths from stroke, lung cancer and heart disease, showing that air pollution has a similar effect to that of smoking tobacco.
Globally, 4.2 million deaths occur every year because of exposure to ambient (outdoor) air pollution with 3.8 million deaths annually as a result of household exposure to smoke from dirty cook stoves and fuel.
In Kenya, nearly six million households use firewood as the main source of cooking fuel, and this exposes them to indoor air pollution.
“Policies aimed at cleaning up the air can reduce the global burden of asthma and improve respiratory health around the world,” said Susan Anenberg, associate professor of environmental and occupational health at the George Washington University in the US, in a study published in Environmental Health Perspectives in October, which used atmospheric models, ground monitors and satellites with remote-sensing devices to estimate levels of pollution even in parts of the world where ambient air quality measurements are not available.
Dr Anenberg called on policymakers to aggressively target ozone, fine particulate matter and nitrogen dioxide, noting that policies that result in cleaner air would not only reduce the asthma burden, but also other health problems.
The World Health Organisation is supporting the implementation of health-wise policy measures like accelerating the switch to clean cooking and heating fuels and technologies, promoting the use of cleaner transport, energy-efficient housing and urban planning, to prevent illness and death from air pollution.
Efforts also include low emission power generation; cleaner and safer industrial technologies and better municipal waste management.
How to reduce air pollution
The capture of methane gas emitted from waste sites as an alternative to incineration (for use as biogas)
Ensuring access to affordable clean household energy solutions for cooking, heating and lighting
Shifting to clean modes of power generation; shifting to cleaner heavy-duty diesel vehicles and low-emissions vehicles and fuels, including fuels with reduced sulphur content
Improving the energy efficiency of buildings and making cities more green and compact, and thus energy efficient.
Increased use of low-emissions fuels and renewable combustion-free power sources (like solar, wind or hydropower)
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.
However, without an understanding of the baseline air quality in Kenya due to the lack of high-quality air monitoring data, the standards and regulations cannot be enforced.
WHO: Children most at risk from air pollution
A new World Health Organisation report estimates that 600,000 children in the world died from acute lower respiratory infections from breathing toxic air in 2016.
The report reveals that 93 per cent of the world’s children under the age of 15 years are exposed to polluted air that puts their health and development at serious risk.
The effects of polluted air start being felt when the baby is still in the womb, as pregnant women exposed to such air are more likely to give birth prematurely or give birth to smaller babies with low birth weight.
Thereafter, breathing in polluted air triggers asthma and childhood cancers, and predisposes children to a greater risk of chronic diseases such as heart ailments later in life.
Even low levels of pollution are harmful, affecting lung function in children.
Air pollution also has an impact on neurodevelopment and the cognitive abilities of children.
“Polluted air is poisoning millions of children and ruining their lives,” said WHO Director General Dr Tedros Adhanom Ghebreyesus.
"This is inexcusable. Every child should be able to breathe clean air so they can grow and fulfil their full potential.”
Children are more vulnerable to effects of air pollution because they are closer to the ground where the pollutants are at a peak level when their brains and bodies are still developing. Moreover, they breathe more rapidly than adults, hence absorb more pollutants.
"Air pollution is stunting children’s brains, affecting their health in more ways than we suspected. But there are many straight-forward ways to reduce emissions of dangerous pollutants,” said Dr Maria Neira, Director, Department of Public Health, Environmental and Social Determinants of Health at WHO.
The report examines the heavy toll of both ambient and household air pollution on the health of the world’s children, particularly in low- and middle-income countries.
Household air pollution from cooking and ambient (outdoor) air pollution cause more than half of acute lower respiratory infections in children under age five in low- and middle-income countries.
The report recommends the implementation of health-wise policy measures like accelerating the switch to clean cooking and heating fuels and technologies, promoting the use of cleaner transport, energy-efficient housing and urban planning.
To achieve this, governments should adopt measures to reduce overdependence on fossil fuels in the global energy mix, invest in improving energy efficiency and facilitate the uptake of renewable energy sources.
Better waste management can also reduce the amount of waste that is burned within communities and thereby reducing community air pollution.
The exclusive use of clean technologies and fuels for household cooking, heating and lighting activities can drastically improve the air quality in homes and in the surrounding community. Adrams Mulama