Seattle-area residents are known for living “green” lifestyles, striving to use cleaning products that leave a minimal environmental footprint and that don’t worsen allergies or medical conditions. But even the most diligent homeowners don’t always know how to recognize signs that a home needs serious duct or carpet cleaning rather than the usual once-over with off-the-shelf cleaning products.

“Many people in this region have pets and allergies, and more homeowners here are investing in air conditioning systems as summers heat up, which increases the risk of mold,” says Eric Moe, owner of Alpine Specialty Cleaning, a family-run business that has been cleaning homes around Seattle since 1969. “Without proper cleaning, these homes run the risk of accumulating and recirculating dirty air in ducts and developing unhealthy carpet conditions.”

As more homeowners use their forced-air heating system for heat in winter and to fan air in summer – or to circulate cooled air from an air conditioning unit – these ducts are in service all four seasons, Moe notes.

Is it time for a deep cleaning? Here are five signs.

• Your home was built energy-efficient. Energy-efficient homes are sealed tighter than most homes, meaning air recirculates more frequently than in traditional-built homes. This makes duct cleaning more important, as a tightly sealed home with pets, kids or lots of wall-to-wall carpet may accumulate dust, mold or smells faster than in a home where outside air can leak inside more easily.

• Carpets have black lines around their edges, matted fibers or numerous visible stains. If your carpet has black lines around its perimeter or where the carpet hits doorways, that means dirt is infiltrating through gaps in walls, beneath doors, or due to broken screens. Matted fiber may result from soil buildup. Heavy stains need treating for removal.

• Dust has accumulated. If you clean and dust regularly but dust persists, it may be living in ducts and carpets that need a thorough cleaning. Additionally, if you need to frequently change furnace air filters because of dust or other accumulation, that may be a sign your ducts are dirty.

• You’ve got allergies or respiratory health issues. If you’ve got asthma or other respiratory health conditions, or if you’re allergic to common substances like pollen, pet hair or other airborne particles, keeping carpets and ducts professionally cleaned can reduce exposure to irritants at home.

• It smells! Smells may be a sign of mold, moisture problems, or soaked-in stains that need professional cleaning.

How often should you clean carpets? Moe says that most homeowners need professional carpet cleaning at least annually _ as often as every 6 months if pets, crawling babies or toddlers, or allergies or respiratory sensitivities are present.

Ducts typically need thorough cleaning every two to three years, but again, a more frequent cleaning may be necessary if pet hair or the above factors are present in the house. Moe encourages those in the market for a duct cleaner to carefully vet the outfit they hire, making sure that like Alpine Specialty Cleaning the company is certified by NADCA, a duct-cleaning association that holds member companies to rigorous standards.

“Most people clean their ducts first, then turn to their carpets,” he says. “September is typically our busiest month, as people prepare for fall when heating systems are turned on and rain begins. But you can clean carpets and ducts any time of year – they’re year-round systems, especially ducts which carry air for both heat, fans, and air conditioning.”

Alpine Specialty Cleaning was founded in the Seattle area in 1969 by Maurice Moe. Eric Moe and his wife, Bobbie, continue the “Tradition of Quality” and “5 Star Experience” that Alpine has been known for over the years.