In the US, more than 6 million children had asthma in 2016. Worldwide asthma kills around 1,000 people – and prevalence is increasing.
This condition has high economic costs.
Every year in the US more than $ 80 billion is lost due to asthma. This is mainly due to early deaths, medical payments and missed work and school days. The burden is greater for families with asthmatic children, who spend an average of $ 1,700 more on health care than families with healthy children.
An important environmental factor that can contribute to the development of asthma is air pollution from traffic.
In our study, published on April 3, our team identified where in the US children are most at risk of developing asthma due to this type of pollution.
Traffic and asthma
Asthma is probably the most common chronic illness in childhood, according to the World Health Organization.
Asthma presents itself as episodes of wheezing, coughing and shortness of breath due to the reversible, or partially reversible, airflow obstruction. Six out of ten children with asthma worldwide had a form of persistent asthma, meaning that they either used long-term medication or that their condition could not be monitored, even with medication.
Very few studies investigate geographical and spatial variations. This study by Texas A&M University quantified the relationship between traffic exposure and the onset of asthma in children in 48 US states and the District of Columbia
Traffic pollution contains a mixture of harmful pollutants such as nitrogen oxides, carbon monoxide, suspended particles, benzene and sulfur. These pollutants are known to harm health in many ways, causing a number of cardiovascular, respiratory and neurological diseases.
A 2013 evaluation suggested that long-term exposure to common traffic-related air pollutants is related to the development of asthma in children and adults.
A much larger meta-analysis in 2017, focusing on children and more recently published studies, found consistent links between this type of pollution and the development of asthma in children. The researchers concluded that there is now sufficient evidence to show a link between this type of pollution and the onset of asthma in children.
Studies by the non-profit organization Health Effects Institute and the US Environmental Protection Agency have been concluded in this sense.
Identify the problem
Despite this emerging evidence, the burden of asthma in children due to air-related air pollution is poorly documented. Very few studies investigate geographical and spatial variations.
My research team wanted to quantify the relationship between exposure to traffic pollution and the onset of asthma in children in 48 US states and the District of Columbia. We also wanted to make this information available to the public.
In our analysis we looked at 70 million children and performed all calculations at the census block level, the smallest available geographical unit for census data. We have collaborated with researchers from the University of Washington who have modeled the concentrations of nitrogen dioxide, a strong sign of traffic-related air pollution, using satellite images combined with environmental ground monitoring data.
We then derived data from surveys from the Centers for Disease Control and Prevention, which estimate childhood asthma incidence in the US. In addition to data from our air pollution models, we have used this data to determine the number of cases of child asthma caused by exposure to traffic pollution.
Despite the encouraging decrease in air pollution and the associated health burden, there were 141,900 cases of child asthma due to traffic-related air pollution in the US. That is 18 percent of all cases of child asthma
We then created a first-of-its-kind, region-to-city interactive heat map and a city-by-city table with details on the distribution of childhood asthma due to nitrogen dioxide in the US in both 2000 and 2010. Each province is represented and users can explore the data to view the findings for a particular province.
Drop in pollution-related asthma is a victory for public health
Our analysis found that cases of child asthma due to traffic pollution in the US decreased by 33 percent on average between 2000 and 2010. In 2000, we estimated that 209,100 cases of child asthma could be attributed to traffic pollution, while this number dropped to 141,900. fallen in 2010. That is a major victory for public health.
What caused the decrease in traffic-related asthma cases? There can be several causes, including more fuel-efficient vehicles, stricter regulations on nitrogen oxide emissions and possibly a reduction in total vehicle distances as a result of the recession.
Despite this encouraging decrease in air pollution and the associated health burden, there were 141,900 cases of child asthma due to traffic-related air pollution in the US. That is 18 percent of all cases of child asthma.
In addition, we found that children in urban areas had twice as many asthma patients as a result of exposure to nitrogen dioxide compared to children living in rural areas.
Our estimates underline an urgent need to reduce children's exposure to air pollution. We hope that our analyzes and heat maps will better inform policy makers, transport agencies, medical associations and other interested parties about the burden of asthma on children as a result of air pollution.