WILDFIRES | IAQ Wildfire smoke can have serious consequences for human health As wildfire smoke with fine particulates and gases can enter buildings through natural ventilation, mechanical ventilation and infiltration, preventative measures and mitigation can be effective. Steven J. Emmerich is a mechanical engineer in the Energy and Environment Division at the USs National Institute of Standards and Technology. He says either the smoke has to be kept out or removed when it gets in. Keeping smoke out can be achieved through the combination of a tight building envelope, maintaining a positive building pressure, reducing outdoor air intake to a minimum and filtering the outdoor air, he says. Apart from the obvious advice of closing doors, vents and windows in the event of a wildfire, the operation of high-efficiency indoor particle filtration systems (see CIBSE air cleaning technologies guidance at www. cibse.org/knowledge) is recommended by the EPA, as well as by members of the UKs Airbods research group. Removing the PM2.5 38 July 2023 www.cibsejournal.com when it gets in means using better filtration in recirculating HVAC systems, says Emmerich. Many building owners and operators can take advantage of efforts they made to improve building filtration during Covid-19. Measures to consider include disabling economisers and demand-control ventilation, verifying what level of improved filtration a buildings systems can employ, and, potentially, rigging temporary filtration of outdoor air intakes. A number of practical steps to mitigate the impact of wildfire smoke are also recommended by the EPA. If the HVAC system has a fresh air intake, this should be closed or the system turned to recirculation mode. For mechanical ventilation systems, it is important to ensure the correct pre-filters and filters are in place. A MERV 13 filter or one with as high a rating as the systems fan and filter slot can accommodate is recommended by the EPA (see bit.ly/CJEPAfilter). Filters that can stop finer particulates generated by wildfires for example, 1 micrometers (PM1) are available from specialist filtration solution suppliers. If the building operates an evaporative cooler, this should be avoided in smoky conditions, says the EPA, as it can draw more smoke inside the building. Other options, such as fans or window air conditioners, should be considered. A portable air cleaning solution can also be effective in mitigating the impact of smoke. Among studies mentioned in the Berkeley Lab paper, two found that air cleaners in homes reduced PM2.5 by around 65%, and by 63% to 88%, during wildfires. Preparing for the impact of wildfires is very important, and ASHRAE has published a framework that Emmerich says offers practical help with an often overlooked aspect making a plan. Part of that is returning to normal operations after the wildfire smoke episode is over, he says. CJ AUSTRALIAN WILDFIRES: HEALTH IMPACT Australias Black Summer of wildfires in 2019-20 was one of the worst wildfire seasons on record, causing immense destruction and the full impact on health from smoke is still being assessed by researchers. The fires in eastern Australia consumed 24 million hectares of land and killed 33 people, with the resulting smoke estimated to have contributed to a further 429 deaths. Studies looking at the impact of smoke inhalation in Australia and the US indicate that wildfire smoke can lead to premature labour, low birth weight, impaired lung development, and higher use by children of some prescription drugs. Studies in Australia is looking into the long-term impacts of these wildfires; one doctor told Bloomberg (bit.ly/CJWFhealth23 )that, at the height of Black Summer, walking in Sydney would have been equivalent to smoking 37 cigarettes in a day.