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Street dust season afoot, prep starts early April

With springtime temperatures starting to melt snow and ice from roads and streets, the amount of dust and microscopic debris will once more increase, as will methods to curb it. Some 5,000 vehicles will be moved over six weeks in April to enable street cleaning operations.

Lakaisukoneen harja ja pölyä
Mechanical street sweepers use a combination of sprayers and rapidly rotating brooms. Image: Laura Valta / Yle

Tingly eyes and scratchy throats are once more in store, especially for those with allergies or asthma. Melting snow and ice will soon leave behind heightened amounts of dust.

"Street dust causes symptoms for almost everyone," says Anne Vuorenmaa from the Allergy and Asthma Federation. "It isn't just people with allergies or breathing problems who will feel the coming of spring in their throats and sinuses."

Alder trees have already begun to flower in southern Finland, and alder pollen can also affect those with birch allergies.

Street dust is composed of asphalt dust and the industrial gravel used to create traction in icy winter conditions. The height of the dust-induced sneezing season is in March and April, when dry and windy weather flings the tiny particles across cities and towns.

"Bikers and joggers should take stock of the coming dusty weather and choose their routes accordingly,"says Vuorenmaa. "P2-class face masks can be found in pharmacies and hardware stores, and are the best defence against microparticles."

Another across-the-counter health apparatus suggested by Vuorenmaa to combat the sniffles is the so-called neti pot, a plastic jug used to clear the nasal canal with a saline water solution.

Helsinki streets cleaned in early April

The large-scale cleaning and rinsing of Helsinki's streets begins on April 4 this year, almost two weeks earlier than usual. The exact timing of the operations depends on the frequency of night-time frost.

"If the subzero temperatures hold, we can't use water effectively for cleaning so the work will be postponed," says Pekka Isoniemi from the Helsinki Public Works Department.

The worst of the dusty period will be approached with a cocktail of chemicals.

"Street dust will be curbed by spreading a calcium chloride solution into urban canyons where the dust gets trapped. The solution makes the swirling dust adhere to the surface of the roads," Isoniemi says.

In Helsinki's inner city areas real estate services are responsible for cleaning the streets outside the buildings. Sidewalk dust can be swept into the nearby car lanes, where industrial sweeper machines gather it up.

Cars moved for access

Springtime street-cleaning is a challenging project that costs some 2 million euros annually, according to the Helsinki Public Works Department. All in all the cleaning operations last some six weeks, utilising more than 100 cleaning or rinsing-related vehicles.

"The cleansing units are composed of a water tank truck, a rinsing truck, and a couple of street sweepers and vehicle relocation units, all on the same street," says Isoniemi. "A whole street can be addressed in a relatively short time with this kind of hardware."

In order for the cleansing operation to be effective, cars parked on roadsides must be moved out of the way. Car owners are notified of the need for their cars to be moved several days prior to the operations themselves, but the city is nonetheless often obliged to move some of the neglected cars.

"About 5,000 vehicles need to be moved during the six-week stretch, a huge job that really slows us down," Isoniemi says.

The schedule for Helsinki's street cleaning operations is available online at . A text message service is also in place for people who want a heads-up on when their street is up for a scrub.

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