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Running the AC With Smoke Outside: Is It Safe to Do?

July 12, 2023

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Is running the AC with smoke outside safe, or somehow unhealthy for people? Also, does it put added wear and tear on the appliances? If you live in any area prone to wildfires, these are excellent questions!

Running an air conditioner with smoke outside can introduce unhealthy air to your indoor spaces. However, in some cases using an AC is safe. This depends on outdoor air quality, your home’s ventilation and filtration systems, and local guidelines.

Before you suffer through another wildfire season in an overly warm environment, keep reading! There are ways of minimizing health risks and damage to your air conditioner.

Also, some general guidelines on using HVAC appliances during inclement weather can ensure you keep them in good working order. Above all, talk to an air conditioning repair contractor near you with questions about your property’s appliances.


running the ac with smoke outside

Is Running AC With Smoke Outside Safe?

There is no “one size fits all” answer about running an AC with smoke outside. However, knowing more about the pros and cons of doing so can help you make the right decision.

Air Quality

Assess the air quality in your area during smoky conditions. Is the air quality significantly compromised due to smoke from wildfires, industrial emissions, or other sources? If so, it's generally advisable to limit outdoor air intake. This will minimize exposure to harmful pollutants.

Filtration System

Check the air filters in your AC unit. Note their efficiency and strength. High-efficiency HEPA filters can remove lots of fine particles and smoke from incoming air. However, standard AC filters aren’t as effective in capturing smoke particles, and some may even allow smoke to enter your interior spaces.

Ventilation Settings

Understand the ventilation settings of your AC unit. Note that some AC systems have the option to switch to recirculation mode. This circulates and filters indoor air without bringing in fresh outdoor air. In turn, you can maintain better indoor air quality during smoky conditions.

Health Considerations

Does anyone in the home have special health conditions? Pre-existing respiratory conditions such as asthma or chronic obstructive pulmonary disease (COPD) make a person more sensitive to smoke. In such cases, it’s good to minimize exposure to outdoor air and seek alternative cooling. For instance, you might use air purifiers or room fans.

Local Guidelines

Local authorities might have specific guidelines or recommendations when it comes to running AC units during smoky conditions. Check for specific instructions or suggestions, which are often based on local air quality conditions.


running the ac with smoke outside

Understanding How Your Air Conditioning Works

Understanding how an air conditioner works can tell you if it’s safe to run during wildfires or smoky conditions. A central air conditioner cools and dehumidifies the air in an entire building, such as a home or office. Central AC units use refrigeration to operate.

The indoor unit contains an evaporator coil and a blower fan. The evaporator coil is a network of refrigerant-filled tubes that absorb heat from the indoor air.

The blower fan in the indoor unit draws warm indoor air and blows it across the evaporator coil. As the air passes over the coil, it transfers heat from the air to the refrigerant in the coil, cooling the air. The refrigerant absorbs that heat, lowering the air temperature.

Note that this process doesn’t pull outside air into your home. However, it’s not unusual for some exterior air to circulate with that cooled air. In turn, some smoke might get into the home while the AC operates.

Also, note that some units have a “fresh air” switch that purposely draws outside air into the home. If you notice this switch on your unit, ensure that it’s turned off! This helps block smoky air from entering while the unit cycles on.

Lastly, note that the AC pulls air through the furnace filter as it operates. In turn, it can help to clean air inside the space. Consider some added information about this process.

Does an AC Clean the Indoor Air?

In some cases, running an AC with smoke outside can help clean and purify indoor air. How so? Central air conditioning systems use air filters to capture dust, pollen, pet dander, and other airborne particles. These filters remove larger particles from the air as they operate.

Air conditioners also help control indoor humidity levels by removing excess moisture from the air. High humidity promotes mold, mildew, and other allergens. In turn, by reducing humidity, air conditioners can indirectly contribute to better indoor air quality.

However, standard air conditioner filters are not designed to remove very fine particles or pollutants like smoke effectively. They also don’t necessarily remove chemical pollutants, gasses, or odors. To effectively address indoor air quality concerns, homeowners should consider additional purifying measures.

Please note that this may differ with window air conditioners.

Does Wildfire Smoke Damage an Air Conditioner?

The short answer is yes, outdoor smoke from wildfires can potentially damage an air conditioning system. Note a few of these risks and considerations to remember when running your AC during smoky conditions:

  • Smoke particles can accumulate on the air filters, evaporator coil, and condenser coil. This reduces the system's efficiency and impedes proper airflow. In turn, you might notice decreased cooling performance, increased energy consumption, and system malfunctions.
  • Smoke often contains acidic particles that corrode metal components in the air conditioning system. This includes condenser coils, electrical connections, and other exposed parts. Corrosion weakens the system and affects its overall lifespan.
  • Smoke can contain soot and fine particles that may infiltrate electrical components such as control boards, capacitors, and switches. This can potentially cause electrical shorts, disruptions in circuitry, or other electrical problems.

How Can You Run Your AC System Safely With Smoke Outside?

Despite the considerations, you can usually run your AC system safely with smoke outside. Note some suggestions for reducing damage risks:

  • Turn off the system when you can, to reduce wear and tear. Also, if you notice visible smoke entering the outdoor unit, shut it down to prevent further damage. This avoids drawing smoke particles into the unit or circulating them indoors.
  • Cover the outdoor unit with a breathable tarp or cover designed for HVAC equipment. This provides some protection against smoke particles and debris while still allowing proper airflow.
  • According to, it’s also good to use a high-quality filter for your system. Also, replace these often for improved air quality.
  • After a wildfire or smoke subsides, have a professional HVAC technician inspect and clean your air conditioning system. They can check for smoke-related damage, clean the components, replace filters, and ensure it’s functioning properly.

Above all, be sure to switch off the unit if you notice it’s pulling in smoke or bad odors. Also, avoid using fans that pull air from outside. If necessary, evacuate to a designated clean air shelter. These steps ensure your health no matter the conditions outside!

Rhode Island HVAC Services is happy to help discuss running an AC with smoke outside. Hopefully we’ve given you some good information to consider! If you’re in the state, call our Rhode Island AC repair contractors as well. We’ll schedule a consultation and prepare a comprehensive price quote. We guarantee all our work for parts and labor, so don’t hesitate to reach out!


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