Bacteria in school dust and the functioning of children's lungs

This affects the air quality in schools

We know that the air quality in school rooms can be influenced by pollution, humidity, ventilation, temperature, humidity and biological factors such as fungi and bacteria, said Dr. Soutrik Banerjee from the Faculty of Environmental Sciences and Prevention at the University of Ferrara in Italy.

However, much less is known about whether the types of bacteria growing in classroom dust are related to children's lung function, he added.

We were particularly interested in two groups of bacteria, Streptomyces and Mycobacterium spp., which occur in soil, dust and water systems. We wanted to check whether greater exposure to these bacteria in school classrooms is related to the lung health of children in Europe, he explained.

The students underwent spirometry

The team used data from the SINPHONIE study, covering 22 European countries and almost 300 classrooms, to measure the amount of Streptomyces and Mycobacterium spp. bacteria in classroom dust.

They also tested the lung function of children in each grade using spirometry, a standard test in which you take a deep breath and then exhale as forcefully and quickly as possible into a measuring device. This device calculates the volume of air that the lungs can hold and the rate at which that volume of air can be exhaled.

Reduced lung function occurs when the lungs cannot hold as much air as normal or the air cannot flow freely through the lungs. This limits the amount of oxygen your body takes in and your ability to remove carbon dioxide, which can lead to fatigue and shortness of breath.

What were the results of the study?

The researchers adjusted the data for age, gender, body mass index (BMI), secondhand smoke, pet allergens, socioeconomic indicators, school building age and region, and local air pollution levels.

They found that children in classrooms with higher levels of Streptomyces bacteria had 0.08 liters lower forced vital capacity (FVC), which is a measure of the maximum volume of air a child can exhale after taking a deep breath.

It was also found that children in classes with higher Mycobacterium levels had slightly lower FEV1 (0.06 liters lower) and PEF (0.13 liters/s lower) values. FEV1 shows how much air a baby can blow out in the first second, and PEF is the maximum airflow a baby can blow out in the shortest possible time.

Significant impact on children's health

As Dr. Banerjee noted, although the observed declines were small for each child, they are statistically significant and may have implications for the broader population.

Children are exposed to the school environment every weekday, and mild to moderate reductions in lung function today may be a precursor to preventable lung diseases later in life, he emphasized.

He believes that bacteria in dust can irritate the respiratory tract or activate immune and inflammatory pathways. The scientist also believes that these bacteria may be markers of other conditions in classrooms, such as humidity, ventilation, cleaning practices or outside dust entering the building.

The bacteria may have a direct biological impact or may be indicators of other indoor environmental factors that affect lung function, he added.

"Schools should become sterile environments"

This large European study shows that children's lungs appear to suffer when two common types of bacteria grow in classroom dust, said Professor Alexander Möller, head of the Pediatric Team of the European Respiratory Society and professor of pediatric pulmonology at the University Children's Hospital Zurich in Switzerland. The scientist was not involved in this research.