‘Un­prece­dented’ wild­fire smoke in Lower Main­land, re­port says

Vancouver Sun - - CITY - JEN­NIFER SALT­MAN jen­salt­man@post­media.com twit­ter.com/jen­salt­man

This sum­mer’s episodes of wild­fire smoke drift­ing from the B.C. In­te­rior into the Lower Main­land were “un­prece­dented” in their du­ra­tion and the geo­graphic area they af­fected, ac­cord­ing to a Metro Van­cou­ver staff re­port.

The re­port, which se­nior project en­gi­neer Fran­cis Ries pre­pared for the cli­mate ac­tion com­mit­tee, noted that the re­gional dis­trict is­sued five air-qual­ity ad­vi­sories dur­ing the sum­mer of 2017, re­sult­ing in ad­vi­sories be­ing in ef­fect for a record 19 days.

Metro Van­cou­ver op­er­ates the air-qual­ity ad­vi­sory ser­vice for the en­tire lower Fraser Val­ley air­shed, in­clud­ing the Metro Van­cou­ver re­gion and the Fraser Val­ley Re­gional Dis­trict. The B.C. Min­istry of En­vi­ron­ment is­sues air-qual­ity ad­vi­sories for the rest of the prov­ince.

An ad­vi­sory for ground-level ozone — a main con­stituent of smog that is formed when ni­tro­gen ox­ides and volatile or­ganic com­pounds re­act in sun­light — was in place July 6 and 7. An ad­vi­sory for fine par­tic­u­late mat­ter from for­est fires was in place July 18 and 19. Three ad­vi­sories for both groundlevel ozone and fine par­tic­u­late mat­ter were in ef­fect Aug. 1-12, Aug. 29-30 and Sept. 4-9.

Hot­ter than usual weather com­bined with wild­fire smoke from the In­te­rior re­sulted in the high num­ber of days with ad­vi­sories.

The re­port com­pared this year’s smoky con­di­tions to what the re­gion ex­pe­ri­enced dur­ing the 2015 wild­fire sea­son.

The lev­els of fine par­tic­u­late mat­ter in the air were “some­what” lower than those mea­sured at the height of the July 2015 wild­fire ad­vi­sory, “but both the du­ra­tion and geo­graphic scope of wild­fire smoke im­pacts in 2017 sig­nif­i­cantly ex­ceeded those ex­pe­ri­enced in 2015.”

Sim­i­lar to 2015, ground-level ozone ad­vi­sories had to be added to wild­fire-smoke ad­vi­sories. How­ever, de­spite re­duc­tions in tem­per­a­ture and so­lar ra­di­a­tion, ground-level ozone pro­duc­tion ac­tu­ally in­creased dur­ing two of the smoke-re­lated ad­vi­sory events. Both hot tem­per­a­tures and so­lar ra­di­a­tion, which con­trib­ute to ground-level ozone pro­duc­tion, are of­ten re­duced by the pres­ence of smoke in the air.

DAR­RYL DYCK/THE CANA­DIAN PRESS FILES

Hot­ter than usual weather and wild­fire smoke bumped up the num­ber of air-qual­ity ad­vi­sory days.

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