Radon, Mold, and Environmental Risks: What 2026 Buyers Should Test For

Demand for environmental and specialty testing is rising. In 2026, more buyers—especially younger and first-time buyers—want to know about radon, mold, and other environmental risks before they close. Here’s what to consider beyond the standard home inspection.

Radon is a colorless, odorless gas that can accumulate in basements and crawl spaces and pose a long-term health risk. In Washington and many other states, radon levels vary by area; testing is recommended for below-grade living space. A short-term test (a few days) or long-term test (months) can be placed by your inspector or a radon specialist. If levels are high, mitigation systems are available and often cost a few thousand dollars. Radon testing is one of the most common add-ons to a standard inspection.

Mold can show up in damp basements, crawl spaces, bathrooms, and anywhere water has intruded. A standard inspection may note visible mold or conditions that favor growth (e.g., moisture, poor ventilation), but it is not a mold assessment. If you see or smell mold, or the inspector flags moisture, a dedicated mold inspection or testing can identify species and extent. Remediation and moisture control are then planned accordingly.

Other environmental considerations include water quality (well testing), lead (older paint and pipes), and asbestos (in older homes, often in place if undisturbed). When to go beyond the standard inspection: when the property has a well, when the report notes moisture or musty conditions, when the home is older and you want peace of mind about lead or asbestos, or when local norms or your own risk tolerance suggest it. Your inspector can recommend when to bring in specialists and what tests make sense for your situation.