The cases of asthma, and the costs related to traffic related air pollution, are much higher than generally perceived, according to a study published in the early online version of the European Respiratory Journal.

Resource economist Sylvia Brandt, from the University of Massachusetts Amherst, along with colleagues from California and Switzerland, revised the cost burden for asthma cases. For the first time they included childhood cases, and showed how many of these childhood cases were linked to air pollution.

The study was conducted in communities within Long Beach and Riverside, California, with high regional air pollution levels and large roads near residential neighborhoods.

The research team found that asthma caused by air-pollution in these neighborhoods, were about $18 million per year, and half of that amount was due to new cases of asthma caused by pollution.

Study results also revealed that a single episode of bronchitic symptoms cost an average of $972 in Riverside and $915 in Long Beach. Additionally, researchers say that those also living in large cities may share the same numerical outcome, compared to those people living in smaller cities that have less areas with pollution.

The overall annual cost for a typical asthma case was $3,819 in Long Beach and $4,063 in Riverside. “The largest share of the cost of an asthma case was the indirect cost of asthma-related school absences,”the authors write. “School absences are an important economic consequence, they add, because they often lead to parents or caregivers missing work.”

Brandt states that families with children who have asthma are most impacted by these exorbitant costs.

“Families with children who have asthma are bearing a high cost. The total annual estimate between $3,800 and $4,000 represents seven percent of median household income in our study in these two communities. This is troublesome because that is higher than the five percent considered to be a bearable or sustainable level of health care costs for a family,” said the authors, in a statement .

Both Riverside and Long Beach make up nearly seven percent of California’s total population, said the authors. This further proves how “truly substantial” the costs of asthma really is, especially those cases related to air pollution.