Asthma is a common chronic condition that affects millions around the world. For those that are able to access medical treatment, symptom management is possible through the use of inhaled corticosteroids. In fact, it can be so effective that many are able to live unobstructed lives with minimal symptoms.
But despite our modern medical solutions, a worrying trend has been emerging. Over the past 40 years, the number and severity of asthma cases have been steadily increasing with no anticipation of slowing down.
The latest numbers in 2019 show that asthma affected approximately 262 million people globally and was the cause of 461,000 deaths.
In the US, the rate of prevalence of asthma was only 3.1% in 1980. This increased to 7.8% in 2019, and asthma emergency department visit rates have also risen by about 10% from 2006 to 2014.
For many, the scariest part is that asthma affects many children. In fact, it's the leading chronic disease for this demographic.
So why do asthma cases keep creeping up year after year? Well, researchers are saying that climate change may be to blame as it changes the quality of the air we breathe.
To understand the connection between long-term changes in our weather and asthma numbers, we first have to look at what causes the condition.
Asthma is the #1 chronic disease among children.
Asthma causes the US to lose $56 billion annually.
The financial burden on patients with asthma in different Western countries is approximately $300-$1,300 per patient per year.
CDC reports indicate that the number of Americans with asthma grew by 28% from 2011-2021
Why someone develops asthma usually comes down to a combination of several predisposing and triggering factors.
Predisposing factors include things like:
Other health factors (e.g. if you have other allergic conditions like Eczema)
Birth factors like low birth weight or prematurity
Key triggers of an acute asthma attack include environmental factors like:
Allergens: Pollen, mould, dust mites, pets, allergic chemicals, and more.
Irritants: Air pollutants (like traffic pollutants or haze caused by forest fires), particulate matter, high ozone levels, and more.
Other health conditions
In addition to medication, managing or preventing Asthma largely has to do with avoiding environmental factors like allergens and irritants.
However, this is only going to get harder as rising global temperatures are closely linked to increasing the amount of these triggers in the environment — particularly pollen and air pollutants.
Pollen is an allergen and one of the most common triggers of asthma attacks.
It's a powdery substance that plants produce to fertilize other plants in the same species. Given that it's very light and airborne, it can be easily inhaled and result in allergic asthmatic episodes.
Despite its small size, the impact that it has on society is big. Such pollen-induced asthma episodes result in about 20,000 emergency room visits a year in the US.
Unfortunately, this is only set to get worse as researchers are seeing a pattern of increasing pollen being produced over more weeks and months within a year.
So, what's going on with the plants?
These changes in pollen production are actually due to climate change as a result of 2 main human-related processes:
Plants need water, sunlight, and CO2 for photosynthesis which helps them produce enough energy for growing and producing pollen.
As we burn fossil fuels as part of our energy consumption, this leads to more CO2 being released into our environment and gives plants more of what they need to produce pollen.
Atmospheric carbon dioxide concentrations have risen from 280 parts per million (ppm) in the 1800s to 420 ppm today.
If we continue at this pace, highly allergenic pollen from plants like ragweed is expected to increase by 60-100% in about 60 years. Grass pollen (which is another common allergen) is also expected to double by 2060 and triple by 2085.
If you're wondering if this is just part of natural changes in the weather, it's not. In fact, around half of the increase in the length of pollen seasons in North America is accounted for by human impact on our climate.
CO2 is a greenhouse gas which means that it easily traps the sun’s heat energy in the earth’s atmosphere. As the concentration of CO2 increases in the environment, this also leads to the planet warming up even further.
Over the past 50 years, the average number of days above freezing has increased by 10 days. While in a global study, researchers found that several countries saw between 1-2 more days of pollen production as a result of the loss of 1-3 days with frost.
This pattern of warmer winters and earlier springs is allowing plants more days to stay active for longer periods and produce pollen outside of their usual cycle.
Unfortunately for asthma patients, this means attacks may start happening earlier and lasting longer than expected in the years to come.
Another thing lingering in the air that's increasing asthma numbers are pollutants.
About two-thirds of people with asthma report that poor air quality exacerbates their condition and can even trigger an attack. For many, this is made worse by the fact that avoiding such environments is almost impossible. WHO research indicates that 8 in 10 people living in urban areas are exposed to air pollution levels that do not pass guideline limits.
Some of these asthma-triggering air pollutants do occur naturally in our environment. But a lot comes about due to human activities (like car emissions), and is the cause of why we're seeing sharp increases in pollution levels.
In a study conducted by the WHO across 67 countries, air pollution increased by 8% from 2008-2018. Furthermore, 65% of excess deaths due to air pollution can be attributed to fossil fuel-related emissions.
Here's a look at some of the most common air pollutants affecting those with asthma:
Many of us have come across the term "ozone layer" which generally refers to the naturally-formed upper part of our atmosphere that helps block out the sun's harsh UV rays.
However, a more harmful type of ozone is lurking in our air that many aren't aware of. And this is called "ground-level ozone". It's produced through sunlight interacting with gas emissions (like nitrogen and sulphur oxides which are also pollutants) from cars and factories.
This toxic mixture of ground-level ozone with nitrogen and sulphur oxides forms the main part of what we term "smog". We often see higher concentration levels during the summer months and afternoon toward early evening.
The link between ground-level ozone and asthma aggravation has been widely studied, and is likely to be one of many causes of asthma development. Even increases by 50 parts per billion (50ppb) for an hour can lead to increased asthma symptoms like wheezing and chest tightening in children — resulting in higher proportions needing emergency treatment.
Particulate Matter (PM) consists of any type of solid particle or droplet in the air. This includes things like small bits of dust, dirt, and smoke. Some may be visible, but the vast majority can't be seen with the naked eye. As particles get smaller, the deeper they're able to enter the lungs and cause breathing issues.
Studies have shown that PM exposure results in worsening asthma symptoms in children. On the other hand, those with asthma who have access to indoor PM filtration devices experienced reduced respiratory inflammation.
Is PM avoidable? It's most likely not be possible to fully eradicate it as many particles are naturally occurring. However, the worrying trend is where we are seeing large increases in human-related PM sources (like car emissions or brake dust). Indoor air pollutant sources are also an issue as approximately 3 billion people use biomass, kerosene fuels, and coal for cooking and the heating of their homes.
While climate change is affecting all regions across the world, the areas which are likely to experience the worst pollen-related health effects are the warmer regions. Within the US, this includes places within states like Texas and Tennessee.
Unfortunately, such locations are more likely to be humid as well. This means that asthma sufferers will have another allergen to battle with — mould. As moisture seeps into homes, mould can easily take up residence and produce spores that trigger asthma allergies too.
Years of scientific literature have shown that the level of income has a part to play in people's exposure to air pollution.
Of the people that do not live in areas that have acceptable air quality, 98% come from poorer countries, while only 56% come from high-income nations. This is also probably why more than 90% of air pollution-related deaths occur in low and middle-income countries. The reason for this is due to a combination of weak environmental laws and reliance on cheap, outdated technologies (like coal power stations) in such regions.
Another issue is the lack of proper diagnosis and medical treatment in such communities. Global research showed that in 2019, only half of those with asthma could access a bronchodilator while less than 20% could access a steroid inhaler in public primary healthcare facilities in low-income countries.
Similar findings have also been documented when examining specific countries. According to the CDC, minority races like African Americans and Puerto Ricans are at higher risk of suffering from asthma, and the same goes for those from lower annual income households.
As we look to the future, disadvantaged groups are likely to be further set back in life as the ones to feel the greatest health impact of climate change — especially if nothing is done to stall or reverse its effects.
The conversation around climate change is often limited to its effect on that environment. But research over the past few decades shows that its impact reaches far beyond that into economic, social, and even health domains.
As we continue to contribute to global warming through our behaviours (like deforestation and burning of fossil fuels), major asthma triggers like pollen and air pollutants are set to increase at exponential rates in the years to come.
The ubiquitous nature of these allergens and irritants means that all segments of society will feel its effect. But socially and economically disadvantaged people are also the most likely to be disproportionately affected, as asthma often goes undiagnosed or untreated in such communities.
It should not be taken for granted that asthma is a treatable condition, as medication is only one part of symptom management. Another big part of the puzzle comes down to avoiding triggers. But if pollen or air pollution rises to a point where it cannot be avoided, a major part of this strategy will be taken away from millions around the world.
Climate change isn't just an environmental issue anymore. Immediate action needs to be taken for the sake of our health too.
The author, Dawn Teh, is a certified clinical psychologist and medical writer.