Houston is a tough place for allergy sufferers. We have year-round pollen because the growing season never stops, mold spores like nowhere else because of our humidity, and we keep our windows closed and air conditioning running for 9 months a year, which means whatever is in your indoor air gets recirculated all day.
The good news: most of the levers that move indoor allergen levels are HVAC levers. Below is the rank-ordered list of what works, what kind of works, and what is sold to allergy sufferers but doesn't actually do much.
The four indoor allergens that matter most in Houston
- Dust mites. Microscopic critters that live in soft furnishings. They feed on shed skin and thrive at 70 to 80 degrees and 60 to 80 percent humidity. Their droppings (not the mites themselves) are the allergen.
- Mold spores. From colonies in HVAC systems, bathrooms, behind walls after water events, in attics, and on damp surfaces. Year-round in Houston.
- Pet dander. Particles of skin and saliva from pets. Tiny and sticky, embeds in carpet and fabric and recirculates through HVAC.
- Pollen. Tracked in on shoes, clothing, pets. Concentrates on furniture and floors. The "season" in Houston is essentially year-round (cedar in winter, oak in spring, grass in summer, ragweed in fall).
Lever 1: Humidity, between 40 and 50 percent
Dust mites cannot survive below 50 percent relative humidity. Mold cannot grow well below 60 percent. Hold your indoor humidity at 45 percent and you have made your house hostile to two of the four major allergens.
Houston outdoor humidity is 70 to 90 percent. AC removes moisture as a side effect of cooling. So:
- If your AC is correctly sized and runs long cycles, indoor humidity sits in the 45 to 55 percent range automatically. This is the goal.
- If your AC is oversized and short cycles, indoor humidity often sits in the 60 to 70 percent range despite a cool house. You feel "cold and clammy."
- If you have a high-quality AC and still can't get below 60 percent humidity, you may need a whole-home dehumidifier ducted to the return.
Action: Buy a $30 hygrometer and put it in your living room. Check it for a week at different times. If you are over 55 percent regularly, you have a humidity problem and we can address it.
Lever 2: Filtration that matches your ductwork
For pet dander and pollen, filtration is the lever. The right filter for an allergy household:
- 4-inch or 5-inch media filter (large surface area, low pressure drop)
- MERV 11 to 13 rating
- Properly sealed cabinet (no air bypass around the filter)
- Changed every 6 to 12 months
This catches 80 to 90 percent of the dander and pollen passing through the air handler. Combined with running the fan in circulation mode 30 percent of the time, that's continuous filtration of the home.
What not to do: Don't put a MERV 13 1-inch filter in a system designed for fiberglass. It restricts airflow, causes ice buildup on the coil in summer, and can damage the blower over time. Either retrofit a 4-inch cabinet or stay at MERV 8 to 11 in your existing slot.
Lever 3: Address the duct system
Your return-side ducts in the attic are pulling dusty, moldy attic air into your filtered, conditioned home. Industry average is 20 to 30 percent return-side leakage. That is a huge bypass around all your filtration.
Action: Duct leakage test, then aerosealing if leakage is above 15 percent. Cuts dust, mold spore, pollen, and dander loads from the duct path.
Lever 4: Source control at the worst rooms
Bedrooms and basements (where applicable) are usually the highest-impact rooms.
For bedrooms, where you spend 8 hours a night breathing the same recirculated air:
- Allergy-rated mattress and pillow encasements (zip up, dust-mite-proof). $50 to $200, very effective.
- Wash bedding weekly in hot water (130 degrees and above kills dust mites).
- Hard floors over carpet where possible. Carpet is a dust reservoir.
- HEPA-bag vacuum, weekly minimum.
- No pets on the bed if pet dander is a trigger.
For bathrooms and laundry, where humidity drives mold:
- Run the bathroom exhaust fan during and after showers. 15 minutes after.
- Replace exhaust fans that are not actually moving air. Many are clogged with lint.
- Caulk where you see soft caulk and any visible mold around tubs, showers, and sinks.
Lever 5: HVAC system biological control
If your evaporator coil, drain pan, or ductwork has biological growth, every cooling cycle is releasing spores into your home.
- Annual coil clean during tune-up. We pull and clean if accessible.
- Drain line treatment, every 3 months. Vinegar or pan tablets.
- UV-C lamp at the coil. $500 to $800 installed. Useful for high-risk households. Doesn't sterilize air, but keeps the coil and pan free of biofilm.
- Replace flex duct sections that show visible contamination. Cleaning contaminated flex rarely sticks.
Lever 6: Whole-home air purification (when it makes sense)
For households with severe allergies, asthma, or chemical sensitivities, an upgrade beyond filtration helps:
- Trane CleanEffects or comparable EAC. Charges particulate, captures it on collector cells. Removes very small particles (down to 0.3 microns), including pollen, smoke, and many viruses. Requires monthly cell cleaning. $1,000 to $2,000 installed.
- HEPA bypass cleaner. True HEPA filtration. $1,200 to $2,500 installed.
- Whole-home dehumidifier. If your system can't hold under 55 percent RH despite a working AC, ducted dehumidifier with humidistat control. $2,500 to $4,000 installed.
What doesn't help much
- Standalone air ionizers. Most generate ozone and don't reduce particulate meaningfully. Some can worsen asthma.
- "Air purifying" houseplants. Not effective at home-scale air volumes.
- Salt lamps and Himalayan rocks. Decorative.
- Ozone generators. Should not be used in occupied spaces. Ozone is itself an irritant and the EPA does not recommend it.
- Generic duct cleaning. May feel useful but the contamination returns within months if the underlying causes (humidity, leaks, biological growth at the coil) aren't addressed.
Working with your doctor
If you suspect you or a family member has an indoor allergen problem, get tested. An allergist can specifically identify dust mite, mold, pet dander, and pollen sensitivities through skin or blood testing. Knowing exactly what you are reacting to helps prioritize the fixes.
We coordinate with allergists on the home-side fixes. They tell you what to avoid, we tell you how to reduce it in your home.
Cost-ranked fix list
- Hygrometer + mattress encasements + hot-wash bedding. $100 to $250. Always do these first.
- MERV 11 filter and 30 percent fan circulation. $50 a year, plus thermostat setting change.
- Annual HVAC tune-up with coil clean. $99 to $179.
- HEPA-bag vacuum. $200 to $500 once.
- 4-inch media filter retrofit. $400 to $800.
- Duct leakage test and aeroseal. $1,500 to $3,500.
- UV-C lamp at coil. $500 to $800.
- Whole-home electronic air cleaner. $1,000 to $2,000.
- Whole-home dehumidifier. $2,500 to $4,000.
Most allergy households see major improvement at step 5 or 6.
"Customer in Pearland with two kids on inhalers. Their indoor humidity was reading 65 percent on a meter despite the AC running constantly. We sized them down on a system replacement (their old one was 1.5 ton oversized), aerosealed their ducts, retrofitted a 4-inch media filter, and added a UV light at the coil. Six weeks later their humidity sat at 47 percent and the kids cut their inhaler use in half. We did not invent anything new, we just did what works."
Bottom line
Indoor allergens respond to humidity control, filtration, and source control. The fixes are unglamorous but proven. Most homes get major improvement from steps that cost less than $500 plus an annual maintenance habit. If symptoms persist, escalate up the list.
Allergy household? We will assess humidity, filtration, and ductwork in one visit. 281-992-7866 or book online.