Canadian wildfire smoke is once again affecting communities far beyond the areas where the fires are burning. For homeowners in Hagerstown and Washington County, Maryland, the smoke is also raising important questions about wildfire smoke and indoor air quality.

On July 17, 2026, the Maryland Department of the Environment issued a Code Purple Air Quality Alert for the Hagerstown area. Code Purple means air pollution has reached levels considered very unhealthy for the general population, with a greater risk of health effects for everyone.

Although staying indoors can reduce your exposure, outdoor smoke can still enter your home. Your windows, doors, ventilation, and HVAC system can all affect how much smoke gets inside and how well your indoor air is filtered.

Here are practical steps Washington County homeowners can take to protect their indoor air and support their HVAC systems during a wildfire smoke event.

Canadian Wildfire Smoke Is Affecting Washington County

Smoke from Canadian wildfires has traveled south across the Midwest, Northeast, and Mid-Atlantic. Air quality alerts have been issued across multiple states as fine particle pollution moves through the region.

The impact is not limited to Baltimore or the Washington, D.C., suburbs. Hagerstown and surrounding Washington County communities were specifically included in Maryland’s July 17 Code Purple alert. Poor air quality was also expected to linger into the following morning.

Air quality can change quickly as winds and weather patterns shift. Homeowners should check current local conditions through AirNow or the Maryland Department of the Environment before spending extended time outdoors.

How Wildfire Smoke Affects Indoor Air Quality

Wildfire smoke contains a mixture of gases and microscopic particles. One of the greatest concerns is fine particulate matter, often called PM2.5.

These particles are small enough to travel deep into the respiratory system. Smoke exposure may be especially concerning for children, older adults, pregnant people, and those with heart or lung conditions.

A home does not need to smell strongly of smoke for fine particles to be present. Reducing the amount of outdoor air entering the house and improving filtration can help limit exposure.

7 Ways to Reduce Wildfire Smoke Inside Your Home

1. Keep windows and exterior doors closed

Keep windows closed while an air quality alert is active. Limit how often exterior doors are opened, especially when outdoor air quality is at unhealthy levels.

Check weatherstripping around doors and windows. Visible gaps can allow smoky outdoor air to enter more easily.

2. Run your central HVAC system

A central heating and cooling system can help move indoor air through its filter. AirNow recommends using central HVAC systems during smoke events when they are properly configured for recirculation and filtration.

Some systems allow homeowners to set the fan to “On” instead of “Auto.” This keeps air moving through the filter more consistently. However, settings and system capabilities vary, so contact an HVAC professional when you are unsure which setting is appropriate.

3. Check your HVAC filter

Wildfire smoke can cause an HVAC filter to become dirty faster than usual. Check the filter during and after periods of poor outdoor air quality.

Replace it when it appears heavily soiled or when airflow seems restricted. A clean filter also helps your HVAC system operate more effectively.

4. Ask whether your system can handle a higher-efficiency filter

AirNow recommends a MERV 13 or higher filter when the HVAC system can safely accommodate one. However, not every system is designed for a high-efficiency filter. A filter that creates too much airflow resistance can place unnecessary strain on the equipment.

Before changing filter types, ask an HVAC professional which efficiency rating is appropriate for your system.

5. Avoid creating more indoor pollution

During a smoke event, try to avoid activities that add particles or fumes to the indoor air.

These may include:

• Burning candles or incense
• Using a wood-burning fireplace
• Smoking indoors
• Frying or broiling food
• Vacuuming without effective filtration
• Using aerosol sprays
• Running gas-powered equipment near the home

Reducing indoor particle sources gives your HVAC filter less pollution to manage.

6. Create a cleaner-air room

Choose one room where your family can spend time when outdoor air quality is poor. Keep its doors and windows closed and reduce activities that generate dust or particles.

A properly sized portable air cleaner may provide additional filtration in that room. AirNow advises avoiding products that intentionally generate ozone.

7. Keep your home safely cooled

Closing windows during hot weather can make indoor temperatures rise quickly. Use your air conditioning system to maintain a safe, comfortable temperature without opening the home to smoky outdoor air.

If your home becomes too hot or your cooling system cannot maintain a safe temperature, seek an air-conditioned public location with good filtration.

Your HVAC Filter Matters During an Air Quality Alert

Your HVAC filter is one of your home’s first defenses against airborne dust and particles. However, filter performance depends on several factors:

• The filter’s efficiency rating
• Whether it fits the filter cabinet correctly
• How frequently the system circulates air
• The condition of the ductwork
• How long the filter has been in use
• Whether the HVAC system can maintain proper airflow

A filter that is bent, undersized, installed backward, or heavily clogged may not work as intended.

Wildfire smoke can also shorten a filter’s useful life. AirNow recommends keeping replacement filters available and checking them more frequently during heavy smoke conditions.

Signs Your HVAC System May Need Attention

A wildfire smoke event can reveal existing HVAC or airflow problems. Schedule an inspection if you notice:

• Weak airflow from supply vents
• An HVAC system that runs constantly
• Unusual odors coming from vents
• Excessive dust around registers
• A filter that becomes dirty unusually quickly
• Hot and cold spots throughout the home
• Increased indoor humidity
• Unusual noises from the HVAC equipment
• Difficulty keeping the home comfortable with windows closed

These symptoms do not always indicate a serious problem. However, an HVAC inspection can help identify filter, airflow, maintenance, or equipment concerns.

How Snyder’s Can Help With Indoor Air Quality

Indoor air quality involves more than a single product. Your HVAC equipment, filters, airflow, maintenance needs, and the condition of your home all play a role.

Snyder’s Plumbing, Heating & Air Conditioning can help homeowners evaluate their HVAC systems and discuss practical options for improving indoor comfort and air quality. 

Snyder’s is family owned and has served Washington County and the Hagerstown Tri-State area since 1995. The company provides professional plumbing, heating, air conditioning, drain, sewer, and indoor air quality services with a focus on dependable service and honest recommendations.

Schedule Indoor Air Quality Service in Washington County

Wildfire smoke can travel hundreds of miles, but there are steps you can take inside your home. Closing windows, checking your HVAC filter, reducing indoor pollution, and keeping your system maintained can all support healthier indoor air.

Call Snyder’s Plumbing, Heating & Air Conditioning to schedule HVAC or indoor air quality service in Hagerstown, Williamsport, Smithsburg, and surrounding Washington County communities.

Contact us today to schedule an appointment and ask about Snyder’s current specials.