Can Air Pollution Cause Asthma?

In this article, we will answer whether air pollution can cause asthma. We will discuss the link between certain air pollutants with asthma, and which groups of individuals face a higher risk of developing asthma from air pollution. Lastly, we will discuss ways one can prevent asthma from air pollution.

Can air pollution cause asthma?

Yes, air pollution can cause asthma. Air pollution refers to any contaminant present in the surrounding air that can affect our health adversely. 

In this case, air pollution can cause asthma, a condition in which a person’s airways become inflamed, narrow and swell and produce extra mucus, which makes it difficult to breathe. 

What species of air pollution are linked to asthma?

The various species of air pollution that are linked to asthma are listed below.

Ozone (O3)

Ozone is a gaseous molecule which is naturally present in the higher layers of the atmosphere, where it absorbs the harmful UV rays of the sun. However, when present in the lower atmosphere layers, it acts as a pollutant, and can cause asthma .

Ozone has a characteristic pungent odor, which can irritate the inner linings of the airways, as well as the lungs. It can hamper one’s ability to breathe deeply, and reduce lung function.

Ozone formation in the lower atmosphere is due to interaction of sunlight with fumes emitted from vehicles, which contain hydrocarbons and nitrogen oxides (NOx). 

It is a major component of “Los Angeles Smog”, or summertime smog, which occurs during summer in metropolitan cities. Studies show that cities in which LA smog occurs have a higher number of reported cases of asthma patients.

Particulate Matter (PM)

Particulate matter refers to solid or liquid particles in the sub-micron range which are suspended in the air. These are of two types, coarse particulate matter (PM10), and fine particulate matter (PM2.5). Out of this, PM2.5 is a major concern.

PM originates from two sources – either from natural sources, which include pollens, molds, dust particles; or from anthropogenic (i.e.human-based) activities such as combustion, vehicular exhausts, industrial emissions, and so on.

In polluted air, PM is present in higher concentrations. Studies show that exposure to higher concentrations of PM can cause reduction in pulmonary functions. 

Furthermore, PM can contain substances which act as irritants to the throat and nose lining, which can cause asthma, or worsen the condition.

For example, ‘hay fever’, which is related to pollen allergy, serves as a trigger for people suffering from asthma.

Nitrogen dioxide (NO2)

Nitrogen dioxide is a gaseous substance which originates primarily from anthropogenic activities such as vehicular exhausts, emission from industrial chimneys, and combustion of firewood.

Higher concentrations of NO2 are usually associated  with  more  frequent  asthma  symptoms  and  asthma-related problems.

Previous studies have shown a link between exposure to local traffic-related pollution to onset of asthma in children. A study estimated that an increase in NO2 concentration by 20.4 ppb (parts per billion) was associated with a 67% increase in the risk of asthma-related school absence.

Which individuals are at a higher risk of developing asthma from air pollution

Vulnerability to onset of asthma from air pollution depends upon several factors, such as physiological factors (eg.: age, comorbidities, etc.), geographic factors (i.e., whether an individual lives in a city or a rural area, climate), and other factors such as occupation, lifestyle, etc.

On this basis, the following groups face a higher risk of developing asthma from pollution.


Children are vulnerable to the onset of asthma. At a young age, the lungs are still developing, and their breathing rate is relatively faster with respect to adults. 

In a study funded by the US Environmental Protection Agency (EPA), evidence suggests that air pollutants can suppress genes that regulate the immune system’s ability to differentiate an allergen from a dangerous foreign substance, such as a virus or bacteria.

The immune system then goes into action, setting up an inflammatory response whether the substance is harmful or not, which leads to asthma. 

Old people

Old people have a weaker immune system, due to aging. Poor respiratory muscle strength, decrease in elastic recoil, and greater rigidity of the chest wall are often all part of the natural aging process that may contribute to the onset of asthma. 

All these factors combined makes elderly people prone to develop asthma if exposed to air pollution. In the US, asthma affects 4%-13% of individuals aged 65 years or older. 

They are at a 5 times higher risk from dying from asthma or asthma-related issues than the younger population.

People living in crowded cities

Large cities which have a high vehicular traffic and industrial areas have a higher level of pollution, particularly of substances such as NO2, SO2, PM2.5, O3, and CO.

These substances are harmful in nature and their contribution to onset of asthma is well-documented in previous studies. 

In such conditions, even healthy people who had no pre-existing health conditions, as well as people who have a family history of asthma, can end up developing asthma or asthma-related issues if subjected to higher levels of pollution.

Occupational asthma

Occupational asthma refers to development of asthma due to exposure to certain factors in the workplace environment. It is caused due to inhalation of irritants during work.

Occupational asthma can be triggered by many factors, which also include:

1. Chemical dyes and solvents

2. Dust from processes involving wood, flour, grain, etc.

3. Working in a quarry or a mining facility.

4. Working with animals or insects

Occupational asthma is avoidable, and if caught early, can be treated as well.

How to prevent asthma from air pollution

Avoid places with traffic congestion

As it is evident, traffic-related pollution is a major contributor to the onset of asthma. So, it is best practice to avoid areas which have high traffic congestion or are prone to it. If it is convenient, one should travel in off-peak hours when there’s no traffic.

On the other hand, one can choose an alternate way of transit via a route which doesn’t have much traffic and is economical as well.

Check pollution levels before leaving

If you live in an urban area, it would be a good idea to check the pollution levels before leaving, so that you can plan your trip accordingly. 

There are many government and non-government organisations that are responsible for tracking the concentration of major air pollutants in the city and provide real-time data for the public.

Clean your indoor air

An average American spends 93% of their total life indoors. 87% of their life is inside buildings, then another 6% of their life is in automobiles.

Over the last several years, a significant amount of scientific reports provide evidence of air pollution inside buildings and homes, referred to as indoor air pollution (IAP), which is more serious than outdoor air pollution, even in industrialised cities and metropolitan areas. 

Thus, a person has a higher health risk from indoor air pollution than from outdoor air pollution. The best way to deal with IAP is by the following methods:

  • Improving ventilation of the house, which would help to dilute the indoor air pollution level by introducing outdoor air, and carry the pollutants out of the house. Furthermore, you can install exhaust fans at your windows or in the central air ducts to improve the efficiency of ventilation.
  • Using an air dehumidifier to reduce the relative humidity of the home. A high humidity level can promote the growth of mold and mildews, which give rise to spores, which can cause asthma .

  • Avoid smoking or combustion of fuels inside the house, as these processes adversely affect the indoor air quality.

Cigarette smoke contains several toxins, which can act as irritants to the airway and affect the respiration system, thereby causing asthma .

  • You can invest in an air purifier. A major component of IAP is particulate matter (PM). These particles can originate indoors from various sources, or enter the house from the outdoor air.

    PM has serious implications on health, depending upon its composition and abundance, and can also cause premature death in people ailing from respiratory and cardiovascular diseases.

    The best method for reducing PM concentrations is by using an air purifier. Depending upon the size of the room, an adequate air purifier should be used.

    Air purifiers with HEPA (High-Efficiency Particulate Air) filters are best suited for indoor purposes. The presence of an activated charcoal filter and a UV light further increases the efficiency of the filters.

    Air purifiers with HEPA I recommend
NameWhy I recommend it
HATHASPACE smart true Air Purifier for HomeIt filters 99.97% of pollutants, as small as 0.3 microns, and has a coverage area of 700 sq.ft.
LEVOIT Air Purifiers for Home, Smart WiFi Alexa ControlCompact size and can be controlled with an Amazon Alexa or Google Home.

Other FAQs about Air quality that you may be interested in.

Can air pollution cause autism?

Can air pollution cause heart palpitations?

Does air quality worsen at night?


Exposure to air pollution can cause asthma, with intensity varying upon concentration and exposure time. 

Certain pollutants such as NO2, O3, and PM2.5 have more implications to onset of asthma, especially on certain groups of people such as the young and old, people living in metropolitan cities, and people with occupations that can trigger asthma. 

Certain ways to prevent asthma from air pollution is by avoiding places with high traffic activity, by checking pollution levels beforehand and planning the activity accordingly, and by keeping the indoor air clean.

Frequently Asked Questions (FAQs): Can air pollution cause asthma?

I live in a metropolitan city and my family has a history of asthma. Am I at risk for asthma?

Yes, you are at risk for developing asthma. Metropolitan cities have higher levels of pollution, particularly NO2, PM2.5, and O3. These pollutants can cause asthma at a relatively lower concentration than the other pollutants.

Furthermore, asthma is a genetic disease. A study shows that nearly three-fifths of asthma patients have one parent or both with asthma.

How can I, as someone who is affected by asthma, keep myself safe while visiting or travelling through polluted areas?

You can keep yourself safe when travelling through polluted areas by following prevention methods, such as wearing a face mask which can block sub-micron particles from entering your airway.

Furthermore, you must carry a reliever inhaler with you in order to quickly deal with the symptoms. You can ask your doctor or GP to direct you on the type of inhaler you should buy and how to use it.

Does weather play a role in air pollution?

Yes, weather plays a significant role in air pollution. In winter seasons, when the near surface air is cold, a condition of “inversion” exists, due to which the air doesn’t move vertically.

Under such conditions, the pollutants get trapped near the ground surface, and subsequent emissions from various sources increase the pollution levels, thereby making one more susceptible to asthma.

On windy days, the pollutants get unsettled and cannot accumulate, making the air cleaner.

Lastly, certain biological activities that can cause asthma also are dependent on the weather. For example, on warm days, in the absence of wind, people could face a chance of experiencing asthma due to the presence of pollen.


  • Pablo Orellano, Nancy Quaranta, Julieta Reynoso, Brenda Balbi, Julia Vasquez; “Effect of outdoor air pollution on asthma exacerbations in children and adults: Systematic review and multilevel meta-analysis”. PLoS One. 2017; 12(3): e0174050. Published online 2017 Mar 20. doi: 10.1371/journal.pone.0174050
  • Holst G J, Pedersen C B, Thygesen M, Brandt J, Geels C, Bønløkke J H et al. “Air pollution and family related determinants of asthma onset and persistent wheezing in children: nationwide case-control study” BMJ 2020; 370:m2791 doi:10.1136/bmj.m2791

Web references

The Links Between Air Pollution and Childhood Asthma:

Asthma and Allergy Foundation of America (AAFA):

Asthma UK:

Asthma in the Elderly: Important Considerations for Diagnosis and Treatment:

Is Your Job Giving You Asthma?:

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