How Urban Pollution Affects Asthma Development

Living close to a polluted city can cause asthma. Exposure to outdoor pollutants can induce asthma symptoms, exacerbations, and decreases in lung function. Traffic-related air pollution, nitrogen dioxide, and second-hand smoking are significant risk factors for asthma development in children.

Air pollution can cause asthma and other lung diseases

Yes, living close to a polluted city can cause asthma.

People with asthma are at greater risk from breathing in small particles and irritating gases. They can irritate the airways and make asthma worse.

Ozone, a gas, is one of the most common air pollutants. It is very irritating to the lungs and airways. Ground-level ozone is created by chemical reactions between emissions of burning fuel emissions and volatile organic compounds (VOCs), heat, and sunlight. It is associated with worsening respiratory diseases such as asthma and chronic obstructive pulmonary disease (COPD).

Nitrogen dioxide (NO2) comes from burning fuels. It also forms from emissions from cars, trucks, other vehicles, and power plants. It is part of smog (haze). Breathing in NO2 can cause someone to develop asthma. It can worsen lung disease, especially asthma.

Sulfur dioxide (SO2) comes from burning fossil fuels, transportation, volcanoes, and industrial processes. It can be found in smog or haze. SO2 can harm plants (including trees). It can harm your lungs and lead to health problems.

Carbon monoxide (CO) forms from incomplete combustion of fuels and wood. It has no smell. It can be very dangerous when it builds up inside buildings, homes, and cars.

Methane (CH4) is another gas that is part of air pollution. It mostly comes from animal agriculture and in subarctic regions where it is released from melting permafrost. Fossil fuels (oil, gas, coal) and waste (food, landfills, wastewater) also add methane to the air. Methane is 30 times more potent at trapping heat than carbon dioxide (CO2) as a major greenhouse gas that is worsening the climate crisis. Methane can turn into ground-level ozone, which is harmful to human health.

The primary and most well-studied sources of indoor air pollution for children with asthma are secondhand tobacco smoke (SHS), particulate matter (PM), and nitrogen dioxide (NO2).

Children living in US urban centers are at risk for secondhand smoke exposure as multiple studies have found ≥50% of urban children are exposed to SHS. This percentage is higher than expected, as currently 12.4% of US adults and 8.1% of US adolescents are active smokers.

Children with asthma who live in urban neighborhoods experience a disproportionately high asthma burden, with increased incident asthma and increased asthma symptoms, exacerbations, and acute visits and hospitalizations for asthma.

There are multiple urban exposures that contribute to pediatric asthma morbidity, including exposure to pest allergens, mold, endotoxin, and indoor and outdoor air pollution. Children living in urban neighborhoods also experience inequities in social determinants of health, such as increased poverty, substandard housing quality, increased rates of obesity, and increased chronic stress.

The excess asthma burden in children with asthma living in urban communities is caused by a combination of indoor and outdoor air pollution, as well as disparities in social determinants of health.

Air pollution can worsen asthma symptoms, leading to increased hospital visits

Air pollution can worsen asthma symptoms and lead to increased hospital visits.

Outdoor Air Pollution

Outdoor air pollution is a mixture of gases and particles that can be harmful to human health and the environment. It is caused by traffic, power generation, and the burning of fossil fuels. It can increase the risk of getting asthma and worsen the symptoms of those who already have it.

Ozone, a common air pollutant, is particularly harmful to people with asthma. It is a highly reactive gas that irritates the lungs and airways. It is often found in cities with more cars and the burning of fossil fuels. Nitrogen dioxide and sulfur dioxide are also harmful gases that can be found in the air. These gases can cause lung damage and increase the risk of developing asthma.

Indoor Air Pollution

Indoor air pollution is caused by household cleaners, fuel-burning heat sources, tobacco smoke, and toxic fumes from new products. It can also be caused by attached garages, building and paint products, and pesticides. Indoor air pollution poses a health risk, especially to those with asthma.

Impact on Asthma

Air pollution can irritate the airways and trigger asthma attacks. It can also lead to difficulty breathing, decreased lung growth in children, reduced lung function, and the need for emergency treatment. People with asthma are particularly vulnerable to the effects of air pollution.

Vulnerable Groups

Vulnerable groups include people with lung or heart disease, those who work or exercise outdoors, individuals who are pregnant, and people who live near sources of pollution. Low-income communities and communities of color are also disproportionately affected by air pollution.

Mitigation Strategies

To reduce the impact of air pollution on asthma, it is recommended to avoid outdoor activities on days with high pollution levels, use close-fitting masks when outdoors, and live at least 300 meters away from major roadways. Community-level interventions, such as urban planning and the development of walking and cycling paths, can also help reduce respiratory morbidity.

Air pollution can cause early death

Yes, air pollution can cause early death. According to the World Health Organization, almost all of the global population (99%) breathe air that exceeds WHO guideline limits and contains high levels of pollutants, with low- and middle-income countries suffering from the highest exposures. Air pollution is associated with respiratory and other diseases and is a significant source of morbidity and mortality.

Air pollution is a mixture of gases and solid or liquid particles that are harmful to humans when present in the air. It is caused by human activities such as traffic, power generation, and industrial facilities, as well as natural sources such as wildfires and volcanoes.

The main gaseous pollutants include nitrogen dioxide, sulfur dioxide, ozone, carbon monoxide, and carbon dioxide, as well as volatile organic compounds and heavy metals. Particulate matter, which includes fine and coarse particles, is also a major component of air pollution and has been linked to various health issues.

Short-term exposure to air pollution can cause difficulty breathing, worsen asthma symptoms, and lead to increased hospital visits. Long-term exposure can result in reduced lung function, adverse birth outcomes, and an increased risk of developing heart and blood vessel diseases.

Certain groups, such as older adults, women, non-white individuals, and those from lower-income communities, are more vulnerable to the harmful effects of air pollution.

To reduce the risk of premature death due to air pollution, it is essential to implement policies and interventions that address key sources of pollution, such as residential energy use, transportation, and industrial activities.

People with lung disease like asthma are at greater risk from breathing in small particles and irritating gases

People with lung diseases such as asthma are at a greater risk of developing serious health issues from breathing in small particles and irritating gases. These particles and gases can irritate the airways and worsen asthma symptoms.

Small particles, such as those found in haze, smoke, soot, and dust, can lead to serious air quality problems. These particles are called "particulate matter" or PM. The smallest particles (PM2.5) are the most dangerous as they can get deep into the lungs or even into the blood.

Ozone, a gas, is one of the most common air pollutants. It is helpful in the upper atmosphere but can cause problems when found closer to the ground in the air we breathe. Ground-level ozone is part of "smog" or haze and is most common in cities with more cars and the use of fossil fuels. It is associated with worsening respiratory diseases such as asthma and chronic obstructive pulmonary disease (COPD).

Nitrogen dioxide (NO2) and sulfur dioxide (SO2) are also common air pollutants that can worsen lung diseases, especially asthma. NO2 comes from burning fuels, emissions from cars, trucks, and power plants, while SO2 comes from burning fossil fuels, transportation, volcanoes, and industrial processes.

People with asthma are advised to limit their time outdoors, especially during periods of high air pollution, and to stay in well-ventilated buildings. Taking measures to reduce exposure to air pollution, such as wearing masks and using air purifiers, can also help mitigate the risks associated with breathing in small particles and irritating gases.

Asthma patients ought to live at least 300m from major roadways to reduce the impact of pollutant exposure on their asthma

Living in a polluted city can indeed cause asthma and increase the severity of symptoms for those already suffering from the condition. Air pollution is thought to cause oxidative injury to the airways, leading to inflammation, remodelling, and an increased risk of sensitisation. Several pollutants have been linked to new-onset asthma, and long-term exposure to air pollution, especially traffic-related air pollution (TRAP) and nitrogen dioxide, is a significant contributing factor.

A study by Pujades-Rodriguez et al. examined the impact of living near a main road on asthma, concluding that living within 150 metres of a major road did not significantly increase the risk of asthma. However, the study did find a statistically significant association for airway hyper-responsiveness (AHR) at 200 metres from major roads. Another study suggested that distances within 300 to 500 metres of roadways were the most relevant for effects on human health, with a notable increase in respiratory illnesses in those living within this range.

Given the evidence, it is advisable for asthma patients to live at least 300 metres from major roadways to minimise the impact of pollutant exposure on their asthma. This buffer zone can help reduce the severity of symptoms and improve the quality of life for asthma patients.

Additionally, community-level interventions such as urban planning can play a crucial role in reducing respiratory morbidity. "Smart" cities with more green spaces, separated from major traffic arteries and industrial areas, can mitigate the impact of pollution on residents. Developing walking and cycling paths away from motorised streets also encourages a healthier lifestyle while reducing exposure to pollutants.

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