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Off Topic / Re: So . . . Canada's on fire, and it's unsafe to breathe the air again :(
« Last post by GuitarStv on Today at 12:40:26 PM »This was put out by the Australian Institute of Sport (where our elite athletes train for things like the Olympic Games) after the 2019 - 2020 fires which sent smoke completely around the world.
https://www.ais.gov.au/__data/assets/pdf_file/0003/1111098/37016_Exercise-in-bushfire-smoke.pdf
Well, that's not making me feel any better.
PM 2.5 from 51 to 150 - Poor conditions for exercise
• It is highly recommended to complete prolonged high intensity endurance activities (e.g., rowing,
cycling, long-distance running) in a facility with better air quality
• Intermittent exercise (e.g., tennis, netball, beach volleyball, cricket) and power activities (e.g., sprint
training, javelin training, jump training, rugby skills training) represent less risk than prolonged high
intensity endurance activities. However, risk remains elevated above baseline and susceptible athletes
should have a current asthma management plan and relevant medications accessible during the session
• Non susceptible individuals may unexpectedly develop symptoms at these concentrations and should seek medical review early
PM 2.5 of over 150 - Hazardous to exercise outdoors
• All efforts should be made to reduce smoke exposure as much as is practical
• Reschedule events, relocate them indoors, shorten overall time outdoors etc.
• Where there is an intention to play organised high level sport and there are medical staff on site to advise,
these levels of pollution should trigger a discussion between medical staff and officials about the
advisability or otherwise of proceeding with the event.
Consecutive days of exposure to polluted air can have a cumulative effect, lowering an athlete’s threshold for symptoms. There is no research into the effects of repeated smoke exposure. This should be considered if your region has been exposed to increased smoke for several days in succession
Acute smoke exposure also results in dose dependent changes to the local immune cell presence in the lower respiratory tract. In patients admitted to an intensive care burns unit, bronchoalveolar lavage (BAL) fluid demonstrated a shift towards a predominant neutrophil presence in those with worse smoke inhalation injury. (34) The normal macrophage percentage from BAL fluid is 95% and 0.7% for neutrophils. (35) Patients with a grade 0 (no injury) according to the Abbreviated Injury Score demonstrated 41% of neutrophils and 54% macrophages, compared to 94% neutrophils with 6% macrophages in the highest
severity grade 4 category (34) BAL neutrophilia is an indication of the acute inflammatory response caused by the bushfire smoke.
Similar, but lower magnitude changes have also been observed in young healthy firefighters who had a controlled exposure to woodfire smoke. After woodfire smoke exposure standardised at a PM 2.5 of 485ug/m 3 for two hours including a light cycling activity. Bronchoalveolar lavage was conducted 20 hours post intervention. A significant increase of absolute neutrophil percentage to above 8% (36) was observed. Moreover, when healthy participants were exposed to woodfire smoke at 224 ug/m3 for
3 hours with mild aerobic exercises, no changes to BAL cell counts 24 hours after exposure was observed. (37) It is possible that exposure at a level between these two exposure conditions is where healthy individuals begin to experience subclinical effects.
An absolute neutrophil percentage equal to or greater than 50% is generally considered diagnostically supportive of acute lung injury, aspiration pneumonia or suppurative infection. (38) The exposure studies noted above indicate the minimum exposure that
can initiate a localised neutrophilia is likely between 224 ug/m3 and 485 ug/m3, for 2-3 hours. (36, 37) Both studies (36, 38) reported there were no changes in pulmonary function, and a paucity of symptoms. Importantly, these studies were only a one-off exposure without an elevated background exposure. Currently there is no evidence regarding the time required to recover from a one-off exposure or compounding effects of repeating the exposure prior to recovery.
Long-term consequences of bushfire smoke exposure, and other sources of air pollution, are beyond the scope of this position statement.
In June of 2023 we had 21 of 30 days where readings were at or above the 'poor conditions for exercise' level. We were at PM2.5 reading of 75 or higher most of last week, and looks like we'll be in the 100 - 180 range for the rest of this week according to forecasts, with today, Monday, Wednesday, and Thursday going into hazardous territory.
