{"hq_id":"hq-p-hom-000227","name":"Earthquake Natural Gas Leak Detection (Mercaptan, Shut-Off Valve)","category":{"primary":"household","secondary":"disaster","tags":["earthquake","natural gas","gas leak","mercaptan","shut-off","explosion","pilot light","seismic"]},"product_tier":"HOM","overall_risk_level":"high","description":"Earthquakes can rupture natural gas lines — both utility mains and interior piping. Natural gas (methane) is odorless; mercaptan (tert-butyl mercaptan) is added at ~1 ppm as odorant for leak detection. Explosion risk at 5-15% gas-in-air concentration. Post-earthquake protocol: smell gas → evacuate immediately, do NOT use light switches, phones, or anything that creates spark. Shut off gas at meter using wrench ONLY if you smell gas or see damage — once shut off, only utility company can restore. Seismic gas shut-off valves automatically close when shaking exceeds threshold.","synthesis":{"derived_risk_level":"severe","synthesis_confidence":0.5,"synthesis_method":"compound_composition","context_used":"human_adult","context_source":"product_users","exposure_modifier":1.1,"vulnerability_escalated":true,"escalation_reason":"Child exposure group","compounds_resolved":1,"compounds_total":1,"synthesis_date":"2026-05-09","synthesis_version":"1.2.0","methodology_note":"exposure_modifier and adjusted_magnitude are computed from ALETHEIA-calibrated heuristics (route × duration × frequency multipliers, clamped to [0.5, 1.4]). Multipliers are directionally informed by EPA Exposure Factors Handbook (2011) and CalEPA OEHHA but are not regulatory consensus. See /api/methodology for full disclosure."},"hazard_summary":{"sensitive_populations":"all building occupants, elderly (slower evacuation), children","overall_risk":"high","primary_concerns":["Natural gas explosion risk at 5-15% gas-in-air concentration","Post-earthquake gas line rupture (interior pipes, utility connections)","Electrical spark or pilot light can ignite accumulated gas","Mercaptan odorant may be masked or not reach all areas"],"exposure_routes":"Inhalation (gas leak); explosion (ignition of accumulated gas)"},"exposure":{"routes":["inhalation"],"contact_types":["inhalation"],"users":["adult","child"],"duration":"minutes_to_hours","frequency":"event-based","scenarios":["Post-earthquake gas line rupture (interior or utility main)","Gas accumulation in enclosed space → explosion risk at 5-15% concentration","Delayed detection: odorant may not reach all areas or may be masked by other odors","Pilot light or electrical spark igniting accumulated gas"],"notes":"California: seismic gas shut-off valves required for new construction and major remodeling in many jurisdictions. Wrench for manual gas shut-off: keep attached to meter with wire. Post-earthquake: if you smell gas, hear hissing, or see dirt blowing from ground — evacuate, do NOT create sparks (no light switches, no phones until outside). Call 911 and utility from a safe distance. Do NOT re-enter until utility clears. Do NOT shut off gas unless you smell it or see damage — restoration requires utility technician and may take days."},"consumer_guidance":{"usage_warning":"Post-earthquake: if you smell gas, hear hissing, or see dirt blowing — evacuate IMMEDIATELY. Do NOT use light switches, phones, or any spark source. Shut off gas at meter ONLY if you smell gas (use wrench kept at meter). Call 911 from outside. Install seismic gas shut-off valve for automatic protection.","safer_alternatives":["Seismic gas shut-off valve (automatic closure during earthquake)","Wrench attached to gas meter with wire (for manual shut-off)","Natural gas detector/alarm in utility area and kitchen","Know location of gas shut-off valve before earthquake occurs"]},"regulatory":{"applicable_regulations":[{"jurisdiction":"USA -- California","regulation":"California Seismic Gas Shut-Off Valve Requirement","citation":"CPC 1211.0-1212.0","requirements":"Seismic gas shut-off valve required for new construction and major remodeling. Must meet ASCE 25 standard. Valve resets after activation.","compliance_status":null,"effective_date":null,"enforcing_agency":"Local building dept","penalties":null,"source_ref":null}],"certifications":[],"labeling":{"required_disclosures":[],"prop65_warning":{"required":null,"chemicals":[],"endpoint":null,"notes":null},"ghs_labeling":{"required":null,"signal_word":null,"pictograms":[],"hazard_statements":[],"notes":null},"hidden_ingredients":{"trade_secret_protected":null,"categories_hidden":[],"estimated_count":null,"known_concerns":null,"notes":null},"notes":null},"recalls":[],"regulatory_gap":null,"notes":null},"lifecycle":{"recyclable":false,"disposal_guidance":"N/A — building infrastructure.","hazardous_waste":false,"expected_lifespan":"varies"},"formulation":{"form":"varies","key_ingredients":[],"certifications":[]},"materials":{"common":[],"concerning":[],"preferred":[]},"compound_composition":[{"hq_id":"hq-c-org-000044","compound_name":null,"role":"fuel","typical_concentration":null}],"identifiers":{"common_names":["earthquake natural gas leak detection (mercaptan, shut-off valve)"],"aliases":[],"manufacturer":null,"brands":[]},"brand_examples":[{"brand":"Kidde","manufacturer":"Carrier Global","market_position":"mass_market","notable":"CO/gas detector market leader"},{"brand":"First Alert","manufacturer":"Resideo","market_position":"mass_market","notable":"Home safety and gas detection"},{"brand":"Watts","manufacturer":"Watts Water Technologies","market_position":"professional","notable":"Earthquake gas shut-off valves"}],"brand_examples_disclaimer":"Representative branded products of this category. Concerning ingredients listed in materials.concerning[] apply to the category, not necessarily to every named brand. Specific formulations vary by SKU and may have changed since this record was written; consult the brand's current ingredient label before drawing brand-level conclusions.","sources":[{"type":"expert_curation","name":"ALETHEIA Safety Database","date":"2026-03-25"},{"type":"regulation","title":"California Seismic Gas Shut-Off Valve Requirement (CPC 1211.0-1212.0)","jurisdiction":"USA -- California","citation":"CPC 1211.0-1212.0","id":"src_36150efd"},{"id":"atsdr_hcn","type":"report","title":"ATSDR Toxicological Profile for Cyanide","year":2006,"inherited_from_compound":"hq-c-org-000044"},{"id":"cdc_hcn_emergency","type":"report","title":"CDC Emergency Preparedness and Response: Cyanide — Medical Management Guidelines","year":2018,"inherited_from_compound":"hq-c-org-000044"}],"meta":{"schema_version":"4.0.0","last_updated":"2026-03-25","timestamp":"2026-05-14T01:26:36.400Z"}}