Air pollution exacerbates bronchiolitis and pneumonia

Children have an immature immune system that reacts worse to infections. In addition to being smaller, their airways become more easily clogged with inflammation and mucus buildup after an infection. For this reason, acute respiratory infections of the lower tract (ARRI), mainly pneumonia and bronchiolitis, are the most important cause of morbidity and mortality in children worldwide. Every year, about 5 million children under the age of 5 die from acute respiratory infections in the world.

On the other hand, older people are at greater risk of severe respiratory infections because their immune systems are outdated and less efficient, they have reduced respiratory function, and they often suffer from other diseases associated with aging.

Viruses are usually the main actors

Although RABI can be caused by viruses or bacteria, the most severe RABI is currently caused by viruses. The importance of bacterial infections has been reduced by vaccination programs, access to the national health system, and antibiotic treatment. The most common viruses responsible for ARIB are respiratory syncytial virus and influenza virus.

These respiratory viruses are transmitted as droplets that spread from person to person, causing severe respiratory failure due to an uncontrolled host immune response, damage to lung epithelial cells, and decreased respiratory gas exchange.

More serious infections if there is air pollution

Living in big cities, where there is high industrial activity and massive use of vehicles, means that we breathe in a large amount of pollutants every day. And it affects us more than we realize.

To begin with, air pollution affects various aspects of health, including the development and exacerbation of respiratory diseases. There is scientific evidence that both short-term and long-term exposure to air pollution is associated with an increase in hospital admissions, emergency room visits, or home visits due to IRAB in children and the elderly.

In 2019, over 300,000 people in Europe alone died prematurely from exposure to air pollutants. For this reason, in 2021 the World Health Organization (WHO) published and updated global air quality guidelines. These guidelines provide recommendations on new limit values ​​for major air pollutants to protect public health.

In addition, WHO, together with other international organizations (Climate and Clean Air Coalition, United Nations Environment Program and the World Bank), is providing up-to-date air quality information in more than 4,000 cities with the goal of reducing annual mortality by two thirds. due to air pollution by 2030.

The main air pollutants involved in viral ARIABs are particles smaller than 10 microns (PM₁₀), nitrogen dioxide (NO₂), sulfur dioxide (SO₂), carbon monoxide (CO) and ozone (O₃). These pollutants typically damage the airways, increase inflammation, and weaken the immune system.

Why are there more respiratory infections in winter?

In addition to pollutants, climatic factors (temperature, wind speed, humidity, thunderstorms) are also associated with a greater likelihood of infection. This is because they determine the survival and transmission of respiratory viruses, as well as host susceptibility.

In particular, low temperatures and high humidity are often associated with an increased risk of viral ARBI. Low temperatures provide greater stability of the pathogen, increasing its survival. Added to this, high humidity conditions stabilize the airborne droplets that carry the virus from person to person, which increases transmission.

Pollutants and climatic factors interact with each other. For example, cold weather and low rainfall are associated with increased levels of vehicle and smokestack exhaust, leading to elevated levels of NO₂, SO₂, PM₁₀, and CO. A warm climate favors O₃ at ground level, and humidity reduces O₃ pollution.

With this data on the table, there is no doubt that monitoring these environmental factors can help prevent hospital admissions, better plan public health resources, and improve patients’ quality of life.

Daniel Sepulveda Crespo, Research Fellow, Carlos III Health Institute; Isidoro Martinez Gonzalez, Senior Fellow, OPI, Carlos III Health Institute and Salvador Resino Garcia, OPI Fellow, Carlos III Health Institute

This article was originally published on The Conversation. Read the original.

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