A power outage is usually thought of as a problem involving lights, refrigeration, communication, and heating or cooling. Less obvious is what happens to the air inside homes and around neighborhoods when electricity disappears.
Modern buildings depend heavily on electricity to move and filter air. Heating, ventilation, air-conditioning systems, exhaust fans, air cleaners, and many pollution-control systems require power. At the same time, people often respond to outages by operating generators, fireplaces, grills, candles, and other combustion sources.
As a result, a prolonged outage can create a very different air-quality environment from an ordinary day.
Ventilation and Filtration Can Stop
Most central HVAC systems use electrically powered fans to circulate air through a building. When power disappears, those fans generally stop.
This means filtration stops as well.
A home equipped with a high-efficiency HVAC filter may normally remove a portion of the particles circulating through the building. During an outage, that protection disappears unless a separate air cleaner or ventilation system has backup power.
Mechanical ventilation may also stop. Bathrooms, kitchens, basements, workshops, and tightly constructed buildings can depend on exhaust fans or dedicated ventilation systems to remove moisture, odors, carbon dioxide, and pollutants produced indoors.
Without air movement, contaminants released inside the building can remain concentrated for longer periods.
This becomes particularly important during a wildfire smoke event. Closing windows may keep some outdoor particles outside, but without electricity, central HVAC filtration and many portable HEPA air cleaners cannot operate.
Generators Create One of the Greatest Hazards
Portable generators are extremely useful during emergencies, but they introduce one of the most serious air-quality dangers associated with power outages: carbon monoxide.
Carbon monoxide, or CO, is a colorless and odorless gas produced when fuels such as gasoline, propane, diesel, wood, or charcoal burn. It interferes with the body’s ability to transport oxygen and can cause headache, dizziness, confusion, unconsciousness, and death.
A portable generator should never be operated inside a house, basement, garage, shed, carport, or other enclosed or partially enclosed area.
Opening a garage door does not make generator use inside the garage safe.
Federal emergency guidance recommends operating portable generators outdoors and at least 20 feet away from buildings, with exhaust directed away from windows, doors, and vents.
Battery-operated or battery-backup carbon monoxide alarms are especially important during outages because ordinary plug-in alarms may stop functioning when electrical power is lost.
Neighborhood Air Can Change Too
Generators do not only affect the house using them.
During a widespread outage, hundreds or thousands of portable and permanent backup generators may begin operating across a neighborhood, hospital complex, commercial district, or industrial area.
Internal-combustion engines can release carbon monoxide, nitrogen oxides, volatile organic compounds, particulate matter, and hazardous air pollutants.
One residential generator may represent a relatively small source outdoors. A neighborhood where many generators operate continuously for several days creates a larger and more concentrated source of combustion pollution.
Hospitals, data centers, manufacturing plants, telecommunications facilities, and other critical infrastructure may use large stationary diesel or natural-gas generators during outages. These systems are essential for maintaining critical services but still produce exhaust and are subject to environmental requirements depending on their design and use.
Cooking and Heating Can Add Indoor Pollution
The loss of electricity may also change how people cook and heat their homes.
Gas stoves, fireplaces, wood stoves, and other combustion appliances can release nitrogen dioxide, carbon monoxide, particulate matter, and other pollutants. Using them more frequently during an outage may increase indoor concentrations.
Outdoor grills, charcoal burners, camp stoves, and similar devices should never be brought inside as substitute cooking or heating equipment unless the manufacturer specifically designed the appliance for indoor operation.
Candles also create particles and combustion products. A few candles used briefly may contribute relatively little pollution, but numerous candles burning for hours inside an unventilated space can noticeably change indoor air.
Battery-powered lighting avoids both the fire hazard and combustion emissions associated with candles.
Heat and Humidity Create Another Problem
Air quality is not limited to pollutants coming from engines or fires.
When air conditioning stops during a summer outage, indoor temperatures and humidity can rise rapidly. High humidity can make buildings uncomfortable and, if moisture remains elevated for extended periods, can create conditions that favor mold growth.
After hurricanes and severe storms, the problem can become more complicated because the same outage may occur alongside roof leaks or flooding. Damp drywall, carpet, insulation, furniture, and wood provide additional opportunities for microbial growth.
Opening windows may improve ventilation and reduce indoor heat when outdoor air is cooler and cleaner. However, opening them during heavy wildfire smoke, severe ozone pollution, or extreme outdoor heat may make indoor conditions worse.
Residents sometimes have to balance two hazards rather than choosing a single obvious solution.
Wildfire Smoke Makes Outages More Difficult
Wildfires can damage electrical infrastructure at the same time they create severe particle pollution.
Normally, residents may protect themselves by closing windows, operating air conditioning in recirculation mode, and running HEPA air cleaners. A power outage can remove several of those protections at once.
Battery power stations or properly installed backup electrical systems may keep a portable air cleaner, fan, or other small device operating. Community cleaner-air centers, libraries, shelters, or other powered public buildings may also provide an alternative when the home can no longer maintain safe conditions.
Heat remains important. Remaining inside a sealed house during wildfire smoke is not safe if the building becomes dangerously hot.
Preparing Before the Power Fails
Air-quality preparation can become part of ordinary outage planning.
Homes should have working battery-powered or battery-backup carbon monoxide alarms. Generator owners should know where the equipment can be positioned safely before an emergency occurs. Fuel-burning devices should be maintained properly, and households can keep flashlights or battery lighting available instead of relying on candles.
People who depend heavily on filtration during wildfire season may consider how a portable air cleaner could be powered during a short outage.
The larger lesson is that electricity quietly supports many of the systems that keep indoor air comfortable and clean. When the grid fails, ventilation and filtration may disappear just as new combustion sources begin operating.
A power outage therefore changes more than what is plugged into the wall. It can change what people breathe.
References
- https://www.epa.gov/emergencies-iaq/power-outages-and-indoor-air-quality-iaq
- https://www.epa.gov/emergencies-iaq/learn-about-power-outages-and-indoor-air-quality
- https://www.epa.gov/emergencies-iaq/emergencies-and-indoor-air-quality-iaq
- https://www.epa.gov/stationary-engines/basic-information-stationary-engines
- https://www.epa.gov/emergencies-iaq/wildfires-and-indoor-air-quality-iaq
- https://www.epa.gov/wildfire-smoke-course/preparing-smoke-and-heat
- https://www.cdc.gov/carbon-monoxide/about/index.html
- https://www.cdc.gov/natural-disasters/response/what-to-do-protect-yourself-during-a-power-outage.html
- https://www.cdc.gov/natural-disasters/psa-toolkit/prevent-carbon-monoxide-poisoning.html
- https://www.fema.gov/node/generator-safety-stay-safe
- https://www.cdc.gov/mold-health/about/index.html
