How Does Air Pollution Affect Your Asthma?

The World Health Organisation acknowledge the exposure and access to clean, good quality air as a basic health and well-being necessity.

Published: Thursday 31 October 2019



Introduction

The World Health Organisation (WHO) acknowledge the exposure and access to clean, good quality air as a basic health and well-being necessity[1]. The association between short-term and long-term exposure to high levels of air pollution and detrimental effects on health and longevity are widely reported[2] . Air pollution collectively refers to the various gaseous pollutants and particulate matters that are emitted as a result of industry, urbanisation, power plants (such as coal and gas) and automobile activity. WHO summarise 4 key pollutants that form byproducts of industry activity that are most harmful to health and the environment, they consist of: Particulate Matter, Ozone, Nitrogen Oxide and Sulphur Dioxide.

Recommended Particulate Matter Exposure

The UK recommends air quality guidelines for fine particulate matter (PM2.5) are limited to an annual mean of 10 µg/m3 (micrometers per meter cubed) and for coarse particulate matter (PM10) an annual mean of 20 µg/m3[3]. The UK is currently meeting these emission targets following a downward trend since 2011, however, the downward trend is stipulated to plateau suggesting careful attention is needed to avoid a rise in air pollution beyond the advisable limits[4]. Air pollution in the city of London has similarly decreased over the past decade due to the implementation of strict government policy, however, London continues to exceed the WHO guidelines for annual mean of PM2.5 by 50% at roughly 15 µg/m3 per year[5]. To enable a global comparison, reported PM2.5 in 2019: Los Angeles (USA) is 18.4µg/m3, Paris (France) is 20.2µg/m3 and Beijing (China) has a reported annual equivalent of 54.75 µg/m3[6].

The Impact of Toxicants on Asthma and Respiratory Health

Asthma is a common inflammatory disorder characterised by chronic breathlessness and wheezing in response to allergens, pollutants or irritants[7]. Air pollution is a prominent risk factor to those with asthma due to the high level of induced inflammation associated with long-term exposure. Asthma sufferers that live in areas with a high level of air pollution are at an increased risk of an exacerbation of symptoms; elevated concentrations of diesel exhaust particles act as a significant trigger[8]. Particulate Matter (PM) is prevalent air pollutants in urban areas, they are categorised by aerodynamic diameter; common PM diameters range from larger 10µm to smaller 2.5µm particle diameters[8]. The exposure of small particle matter diameters (PM2.5) are acknowledged to be increasingly harmful to the human body where they are able to bypass nose hair filtration and penetrate deep into lung tissue; a relatively large surface area enables the transmission of harmful toxins which can lead to impared lung function and increased risk of respiratory disease with prolonged exposure[8]. Air pollution containing PM are responsible for the worsening of symptoms in those with asthma due to oxidative stress and both inflammation and hyperresponsiveness of the airways[9]. Therefore, it is imperative to ensure asthma treatments are utilised to attenuate the incidence of irritation and worsening of asthma related symptoms.

Rates of Asthma in Urban vs. Non-Urbanised Areas

Due to elevated activity of industry in urban areas, emitted pollutant byproducts consisting of Particulate Matter, Ozone, Nitrogen Oxide and Sulphur Dioxide are released. It has been reported that asthma attacks occur more regularly in urban areas compared with non-urban areas due to poor air quality, reflective of an increase in hospital admissions of asthma patients in 1997-2012 due to both short-term and long-term air pollution exposure[10]. Furthermore, the health hazardous pollutant Ozone, is speculated to be attributable an estimated 1500 fatalities in the UK by 2020 due to respiratory complications[11]. Interestingly, the prevalence of asthma in the UK in rural areas is 15.1% and in urbanised areas 21.5%[12], indicating a urban-rural gradient with the likely underlying factor being air quality. Alongside increased rates of asthma, it has been shown that in urban areas with a high density of trees, asthma attack rates tend to decrease with 50 fewer severe asthma attacks per 100,000 residents per square kilometre[13]. Whilst asthma is common and very manageable, lifestyle choices need to made with respiratory health in mind due to the increased health risks incurred due to air pollution.

How Lifestyle Choices Influence the Effect of Air Pollution on Asthma Symptoms

Smoking

Smokers and former smokers with asthma are increasingly vulnerable to worsening asthma symptoms from air pollution due to pre-existing incidence of lung irritation[8]. It is advisable that those with asthma who smoke, should aim to quit smoking, to significantly reduce the intensity and prevalence of asthma symptoms in addition to the wealth of other important health benefits.

Obesity and Lung Function

It is reported that long term exposure to increased concentrations of Nitrogen Oxide and Sulfur Dioxide due to air pollution propagates more intense symptoms of asthma in obese children compared to non-obese children[8]. Furthermore, lung function is significantly worse in obese adults exposed to Ozone for an extended period of time[8]. Therefore, it is clear that obesity can exacerbate asthma symptoms in environments where air pollution levels are high; effective weight loss treatments should be identified to promote lung function and general health.

Dietary Changes to Reduce the Impact of Air Pollution

A diet including sufficient sources of vitamin D (e.g. Oily fish, cheese, egg yolks) and antioxidants (e.g. fruits and vegetables, seafood and nuts) are key to attenuating the impact of air pollution on asthma[14]. This is supported by research reporting greater vulnerability to fine particulate matter (PM2.5) in children that were both obese and Vitamin D deficient[8].

In summary, to reduce the impact of air pollution where it cannot be practically avoided, it’s crucial to ensure you have an effective treatment for asthma in addition to reviewing your lifestyle choices to optimally support your respiratory health and well-being!

Sources

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