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Pennsylvania -- population 1,602,305

Philadelphia County, PA Property Research

Real data from four public sources, not an internal estimate: the EPA's radon zone classification, Census housing-age records, FEMA's natural hazard risk index, and NOAA's recorded storm history for this county. Every figure below links to where it actually comes from.

Hazard Summary

Philadelphia County, PA hazard summary: FEMA National Risk Index rated Very High; EPA radon zone 3 of 3; most frequently recorded hazard is thunderstorm wind (136 events, 2015-2024).

Radon Risk

Zone 3 -- low potential. EPA predicts an average indoor radon screening level below 2 pCi/L for this county.

This is a county-wide prediction from geology and soil data, not a measurement of any specific home -- EPA recommends testing every home regardless of zone. See our guide on negotiating radon mitigation after inspection.

Source: EPA Map of Radon Zones

Housing Age

Philadelphia County has 739,725 housing units. About 76% were built in 1969 or earlier -- old enough that knob-and-tube wiring, lead-based paint, and galvanized supply lines are all realistic possibilities worth checking for, not just a general inspection line item.

2020 or later
4,412
2010-2019
35,285
2000-2009
23,685
1990-1999
20,046
1980-1989
33,107
1970-1979
57,797
1960-1969
80,371
1950-1959
111,067
1940-1949
78,805
1939 or earlier
295,150

Does knob-and-tube wiring have to be replaced before closing?

Source: U.S. Census Bureau, ACS 5-Year Estimates, Table B25034

Natural Hazard Risk

FEMA rates Philadelphia County's overall natural hazard risk as Very High, relative to the rest of the country.

Heat WaveVery High
Cold WaveVery High
Winter WeatherVery High
Inland FloodingVery High
TornadoRelatively High
Source: FEMA National Risk Index

Recorded Storm History (2015-2024)

NOAA recorded 327 storm events in Philadelphia County between 2015 and 2024. This is actual event history, not a risk model -- the counts below are individually logged storms, not a prediction.

Thunderstorm Wind
136
Flash Flood
73
Winter Weather
40
Flood
19
Excessive Heat
16
Hail
16
Coastal Flood
15
Winter Storm
12
Source: NOAA National Centers for Environmental Information, Storm Events Database

Guides Relevant to This County's Housing Stock

Does a Standard Home Inspection Check for Asbestos?Can Cast Iron Sewer Pipes Fail a Standard Home Inspection?Can I buy a house with knob-and-tube wiring?Can You Get Homeowners Insurance with Knob and Tube Wiring?Does Knob and Tube Wiring Have to Be Replaced Before Closing?What Is a Federal Pacific Stab-Lok Panel and Why Inspectors Flag It?

Get Your Free Property Report

BeforeRegret pulls live seismic hazard data, validates the address, and builds era- and county-specific inspection priorities and seller questions into one report -- with anything not yet independently verified clearly labeled, not guessed at.

Get Your First Report Free

This page reports what these four public agencies have published for Philadelphia County as a whole -- it is not an assessment of any specific address or property, and does not replace a licensed home inspection, radon test, or insurance review for a specific home. Data last checked August 10, 2026.