The dustier the air in Helsinki, the more often City of Helsinki employees were on sick leave, according to findings from a study carried out by the Finnish Institute of Health and Welfare (THL).
The study assessed the link between daily new sick leave numbers and the concentration of respirable coarse particles on the same day and preceding days.
It found that once the concentration of the particles increased by 10 micrograms per cubic metre of breathing air, sick leave increased by 1.8 percent.
"On the worst days of street dust, employees of the City of Helsinki may take several dozen more sick absences than on an average day," THL Chief Researcher Professor Timo Lanki said.
The study funded by the Helsinki Region Environmental Authority (HSY) used sick leave data for City of Helsinki employees as well as HSY’s air quality data. It studied almost two million annual absences of city employees between 2002 to 2017.
Tram drivers among worst affected
According to the results of the study, tram drivers in the capital region were particularly affected — sick leaves among the group saw an increase of 6.8 percent on days with high concentration of street dust in the air.
Lanki said tram drivers were studied as a professional group because they are most exposed to dust in their work. The study did not separately examine any other occupational groups.
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Surprisingly, the study found that although street dust levels are particularly high in the spring, no association was found between street dust and increased sick leave during springtime.
Lanki said that further research would be necessary to confirm the matter, as the study had fewer observation days in the spring compared to the whole year.
The health effects of street dust are also still not well known, although it is the most significant source of coarse particles in an urban environment.
Street dust contains many potential contaminants such as quartz, metals, and bacterial endotoxins.
"It is important that research raises people's awareness of the presence of street dust in the air in all seasons," Lanki said.
Helsinki wants to restrict use of studded tires
HSY air quality expert Outi Väkevä said the amount of dust in the air can be reduced by favouring friction tyres instead of studded tyres and by ensuring effective dust control in cities.
"Helsinki has been active in developing street washing methods. We also have no shortage of clean water, which means we can pressure wash the streets," Väkevä said.
During spring the streets are also treated with diluted saline to bind the dust.
The new Road Traffic Act, which came into force in the summer, makes it possible to restrict the use of studded tyres under the guidance of a new traffic sign. The City of Helsinki has launched a study mapping out sections of the street where the ban on studded tyres could apply.
