Smoke A guide to the fire season What is Smoke? Smoke consists of: potentially harmful gases (carbon monoxide, sulfur and nitrogen oxides, volatile organic compounds) While present, these may cause respiratory irritation or other acute problems, but are often not present in smoke at concentrations that cause long-term health impacts Inert gases (carbon dioxide, water vapour) Particulates These can cause long term health impacts, as they can remain in the body once inhaled What are particulates? Smoke particulates are classed as PM2.5 (particles below 2.5 micrometers (μm) in diameter) and may be smaller than 1 micrometer (PM1.0). Particles in these classes are small enough that they are not filtered out during respiration and enter the lungs. They may also cross into the bloodstream through the lungs, allowing them to affect the circulatory system. Masks and air filters that protect against COVID are generally measured in their effectiveness at filtering PM10 particles (10 μm in diameter) because that's the typical size for an airborne droplet containing viruses. This means that a particular mask or filter that is effective against COVID might not necessarily be effective against smoke. Neither masks nor air filters protect against gases in the smoke. Health Effects of Wildfire Smoke Acute effects Most people will experience upper respiratory symptoms (sore eyes/throat/sinuses, nasal congestion, coughing and wheezing) and headaches Pre-existing respiratory and circulatory conditions (asthma, COPD) may be triggered. As PM2.5 and (particularly) PM1.0 particles are small enough to enter the bloodstream through the lungs, they can have a range of systemic effects on various parts of the body. Circulatory system inflammation Reduced sperm count Pregnancy complications Long term effects Living with 22 μg/m3 of PM2.5 particulates has the same health consequences as smoking one cigarette per day in terms of long-term health effects This number can be found on most weather or air quality apps. If the main pollutant is PM 2.5, it is often wildfire smoke Most provincial and federal weather apps in Canada will begin to classify air quality risks at levels above 30μg/m3, and issue warnings for unhealthy air at 60μg/m3 and 100μg/m3 with increasing severity As the amount of PM 2.5 particulates increases, so too does the risk. For example, an air quality of 500 μg/m3 of PM 2.5 would be equivalent to one cigarette per hour spent breathing unfiltered air, or a little over a pack per day As wildfire smoke is normally only a significant air pollutant for at most a few weeks during the year, the aggregate health consequences are less serious than would be the case in cities that have such high levels of pollution year-round. Pregnancy Concerns There is evidence that maternal exposure to wildfire smoke during early pregnancy may have negative effects on fetal development and makes preterm birth more likely Smoke exposure can cause circulatory inflammation and increase maternal blood pressure, which may trigger preeclampsia. Smoke particles may also be capable of penetrating the placenta and causing circulatory inflammation in the fetus Minimizing smoke exposure is therefore particularly important for people who are pregnant or trying to become pregnant How to Not Inhale Smoke Different types of filter Most filters are not expected to trap 100% of anything. E.G. N95 respirators are so named because they must stop 95% of PM0.3 particles. Furnace filters Basic furnace filters (MERV 6 or worse) do not filter any PM2.5 particles. MERV 8 (lowest level sold as "allergy defence") only filters 20% of PM2.5 particles and do not filter anything below one micron; only marginally better than nothing MERV 11 standard requires the filter to stop 65% of PM2.5 particles; only 20% of PM1.0 particles are filtered. MERV 13 standard requires trapping at least 85% of PM2.5 particles and 50% of PM1.0 particles. MERV 14 (upper end of what's commonly available for furnace filters) requires 90% filtration for PM2.5 and 75% for PM1.0. Filters can also be measured in MPR. MERV and MPR equivalency (for 3M filters specifically): MPR 1000 is comparable to MERV 11. MPR 1900 is comparable to MERV 13. MPR 2200 is between MERV 13 and MERV 14. MPR 2500 is comparable to MERV 14. Higher filtration levels also mean that the filter is more resistant to air moving through it. The resistance to airflow is measured in terms of the static pressure drop across the filter: the air pressure after the filter will be lower than the pressure before the filter. Before increasing the MERV rating of a furnace filter above what's currently in the furnace intake, check the furnace manual to see if it directly states a maximum MERV rating. If it doesn't, look to see if it states the maximum allowable static pressure for the filter and then look up the spec sheet for the new filters to find the static pressure drop that they create. Using a filter with a static pressure that's too high for the furnace can cause the furnace to fail , either by overloading the blower motor or by causing the heating elements to overheat due to not having enough air passing over them. New filters are sometimes worse at filtering than lightly used filters because stuff getting caught on the filter helps catch other stuff. Don't change filters too early. Higher-MERV filters clog faster so will need to be changed more frequently. Masks and respirators Properly fitted N95/KN95/FFP2 and similar respirators are 95% effective against PM 2.5 and PM 1.0 particles. More stringent disposable respirators (N99, N100) are available but are considerably more expensive and may be less comfortable. Reusable N99 and N100 respirators (plastic/rubber frame with replaceable filter canisters are also available. Some of these respirators may also protect against some of the noxious gases that can be present in smoke (if the canisters are labelled as protecting against gases and vapors as well as particulates); if you are particularly sensitive to respiratory irritants then this could be a good idea. Masks with an exhaust valve may be more comfortable due to making exhalation easier, but remember that this type of mask does not protect others against communicable diseases. Headband-type masks seal much better than earloop-type masks and are often more comfortable for long periods. The mask will eventually start to irreversibly clog and fill up with the particles it’s filtering out. Throw out a mask once it’s visibly discoloured or if you start smelling smoke more strongly even with it on. Cloth masks and surgical masks are ineffective against particulates as they don't seal tightly and are too porous Mask effectiveness is severely degraded by facial hair that touches the mask edges. Some N95-type respirators may remain effective over short stubble. HEPA filters Actual HEPA filters will remove almost all particulates from the air they filter (>99.9%) Many products are marketed as "HEPA-style" or similar terms; these are not regulated terms and you should not trust their filtration ability without looking up an independent certification of their PM2.5 and PM1.0 filtration. Air Filters - Buy or Make Purpose built air purifier: Need to make sure the filtered air circulates; many air purifiers don’t have a strong enough fan to do this on their own. Not good at filtering multiple rooms, so prioritize the rooms you spend the most time in and especially places you or someone else can't wear a mask (bedroom, rooms with small children). Always verify that the specific model of air purifier you’re buying has good filtration performance for PM2.5 and PM1.0 particles. Remember that the filter will need to be cleaned/changed periodically Corsi Rosenthal Box A cube made out of filters, a box fan, and tape. How to make guide can be found at https://corsirosenthalfoundation.org/instructions/ Filters must be replaced periodically as the airflow through the box is reduced once they get too clogged. Filter lifespan depends on how often the box is running and on how dirty the air is. MERV 11 filters are "good enough" for a CR box meant to reduce risk of COVID exposure in a home setting, but are not suitable for dealing with smoke as they only filter 20% of PM1.0 particles with each pass through the filter. Recommended materials: Costco MPR 2200 filters or 3M Filtrete MPR 2200 filters. Filters need to be replaced periodically, usually when visibly dirty. For Living box fans, Lasko fans, or Honeywell HF910 You also need packing tape and the box the fan came in (or another cardboard box at least 20" in length and width) Making a cardboard shroud for the fan improves efficiency and reduces noise Quieter boxes can also be made using computer case fans mounted on a wooden frame. Much like an air purifier, must make sure the filtered air circulates; CR boxes generally move more air than air purifiers because the fan is so large, so should circulate better on their own Still not going to be good at filtering multiple rooms, so prioritize the rooms you spend the most time in and especially places you or someone else can't wear a mask (bedroom, rooms with small children). General Advice Keep doors and windows to the outside closed as much as possible while the air is smoky outside Older buildings generally have more natural ventilation through cracks and crevices, so smoke will get in more easily and more filtering power will be needed to keep indoor air quality at a tolerable level Avoid exerting yourself when outside as you will inhale more particulates when you breathe harder. Wearing a mask is an especially good idea if you’ll be doing anything strenuous outside or in a smoky indoor space. If you are required to work in a smoky area, you can discuss with your employer whether they can provide N95 respirators or if you can wear your own. You have the right to refuse unsafe work, and working in smoking conditions may constitute unsafe work depending on the circumstances. Information on Air Quality Ontario Ministry of the Environment https://www.airqualityontario.com/history/pollutant.php? pol_code=124&stationid=51001 Simple hourly readout of current and past two days PM2.5 levels Also has historic data back to 2007 FireSmoke https://firesmoke.ca/forecasts/current/ Live smoke data Forecasting of smoke levels out to 48 hours ahead Also shows locations of wildfires How Many Smokes? https://smokesmap.com Live smoke data Forecasting of smoke levels translates air quality to comparable number of cigarettes smoked Sources What is Smoke? https://www.epa.gov/wildfire-smoke-course/why-wildfire-smoke-health-concern Health effects https://berkeleyearth.wpengine.com/air-pollution-and-cigarette-equivalence/ https://www.fertstert.org/article/S0015-0282(21)00847-5/fulltext https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8975955/ https://www.nbcnews.com/health/womens-health/wildfire-smoke-exposure- pregnancy-risk-preterm-birth-rcna70102 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9657128/ Filters and Masks https://multimedia.3m.com/mws/media/1740587O/filtrete-merv-vs-mpr.pdf https://www.nature.com/articles/s41370-021-00337-1 https://twitter.com/DavidElfstrom/status/1499210537779056640 https://en.wikipedia.org/wiki/Corsi%E2%80%93Rosenthal_Box#/media/File:Corsi- Rosenthal_Box.jpg https://itsairborne.com/building-a-pc-fan-corsi-rosenthal-box-68e7cd1ca570 Refusing Unsafe Work https://www.wsps.ca/resource-hub/articles/wildfire-smoke-in-canada-understand- the-health-risks-to-ensure-workplace-safety https://www.ontario.ca/document/guide-occupational-health-and-safety-act/part-v- right-refuse-or-stop-work-where-health-and-safety-danger