What does a cancer risk of 30 in a million mean?

It is EPA's modeled estimate that about 30 out of every 1 million people breathing the outdoor air at that level for a lifetime could develop cancer because of air toxics. It is a screening estimate for a population, not a prediction for any one person.

Why is background such a large share?

Background is the risk from pollutants that have been in the air for a long time or come from far away, such as carbon tetrachloride. It is about the same everywhere, so local differences come mostly from the other sources.

Is AirToxScreen the same as the old NATA?

Yes. AirToxScreen replaced the National Air Toxics Assessment (NATA) and uses updated emissions and modeling.

Air Toxics Cancer Risk

EPA AirToxScreen, 2020 emissions

U.S. average, all sources: 30.4 in a million; Population-weighted from state results
States and territories: 53
Assessment year: 2020

By state

Average lifetime cancer risk per million people (EPA rounded total)

Swipe the table sideways to see more columns.

State	Total risk	Industrial point sources	Vehicles
Alabama	30 in a million	0.81 in a million	0.86 in a million
Alaska	30 in a million	0.042 in a million	2.1 in a million
Arizona	30 in a million	1.7 in a million	1.4 in a million
Arkansas	30 in a million	0.53 in a million	0.6 in a million
California	40 in a million	0.71 in a million	2.4 in a million
Colorado	30 in a million	1.1 in a million	1.7 in a million
Connecticut	30 in a million	0.44 in a million	1.3 in a million
Delaware	30 in a million	4.7 in a million	1.1 in a million
District of Columbia	40 in a million	2.2 in a million	3 in a million
Florida	30 in a million	0.17 in a million	0.91 in a million
Georgia	40 in a million	0.38 in a million	1.4 in a million
Hawaii	20 in a million	0.33 in a million	1 in a million
Idaho	30 in a million	0.084 in a million	1.1 in a million
Illinois	30 in a million	1.1 in a million	1.6 in a million
Indiana	30 in a million	0.56 in a million	1.2 in a million
Iowa	20 in a million	1.5 in a million	0.75 in a million
Kansas	30 in a million	2.2 in a million	0.81 in a million
Kentucky	30 in a million	0.93 in a million	1 in a million
Louisiana	40 in a million	4.5 in a million	0.59 in a million
Maine	20 in a million	0.081 in a million	0.39 in a million
Maryland	30 in a million	1.1 in a million	1.8 in a million
Massachusetts	20 in a million	0.42 in a million	1.4 in a million
Michigan	20 in a million	0.62 in a million	1.1 in a million
Minnesota	30 in a million	0.63 in a million	1.1 in a million
Mississippi	30 in a million	0.5 in a million	0.52 in a million
Missouri	30 in a million	1.4 in a million	1 in a million
Montana	20 in a million	0.13 in a million	0.68 in a million
Nebraska	20 in a million	0.69 in a million	0.97 in a million
Nevada	30 in a million	0.12 in a million	1.9 in a million
New Hampshire	20 in a million	0.081 in a million	0.78 in a million
New Jersey	30 in a million	0.99 in a million	1.9 in a million
New Mexico	20 in a million	0.85 in a million	1 in a million
New York	30 in a million	0.58 in a million	2 in a million
North Carolina	30 in a million	0.6 in a million	1.1 in a million
North Dakota	20 in a million	0.12 in a million	0.72 in a million
Ohio	30 in a million	0.9 in a million	1.2 in a million
Oklahoma	30 in a million	0.58 in a million	0.92 in a million
Oregon	40 in a million	0.24 in a million	1.9 in a million
Pennsylvania	30 in a million	1.8 in a million	1.5 in a million
Puerto Rico	20 in a million	1.2 in a million	0.46 in a million
Rhode Island	20 in a million	0.89 in a million	1.4 in a million
South Carolina	30 in a million	1.2 in a million	0.96 in a million
South Dakota	20 in a million	0.059 in a million	0.53 in a million
Tennessee	30 in a million	0.94 in a million	1.1 in a million
Texas	30 in a million	3.5 in a million	0.92 in a million
U.S. Virgin Islands	10 in a million	0.013 in a million	0.14 in a million
Utah	20 in a million	1.9 in a million	1.5 in a million
Vermont	20 in a million	0.11 in a million	0.29 in a million
Virginia	30 in a million	1.5 in a million	1.3 in a million
Washington	30 in a million	0.21 in a million	1.8 in a million
West Virginia	30 in a million	1.7 in a million	0.54 in a million
Wisconsin	20 in a million	0.53 in a million	0.91 in a million
Wyoming	20 in a million	0.29 in a million	0.57 in a million

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Counties with the highest modeled risk

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#	County	State	Total risk	Industrial point sources
1	St. John the Baptist	LA	80 in a million	49.2 in a million
2	Clackamas	OR	80 in a million	0.47 in a million
3	Santa Cruz	CA	70 in a million	0.18 in a million
4	Anasco	PR	60 in a million	41.8 in a million
5	Butte	CA	50 in a million	0.063 in a million
6	Ascension	LA	50 in a million	21.1 in a million
7	Salinas	PR	50 in a million	34.4 in a million
8	Sacramento	CA	50 in a million	0.14 in a million
9	Multnomah	OR	50 in a million	0.37 in a million
10	Cape Girardeau	MO	50 in a million	19.7 in a million
11	St. Charles	LA	50 in a million	20.5 in a million
12	Iberville	LA	50 in a million	17.2 in a million
13	Jefferson	TX	50 in a million	19.9 in a million
14	Placer	CA	50 in a million	0.095 in a million
15	Lane	OR	50 in a million	0.36 in a million
16	Weld	CO	50 in a million	1.3 in a million
17	Gregg	TX	50 in a million	11.2 in a million
18	Henrico	VA	50 in a million	13.8 in a million
19	Yuba	CA	50 in a million	0.11 in a million
20	Harrison	TX	50 in a million	9.7 in a million
21	Richmond city	VA	50 in a million	12.3 in a million
22	St. James	LA	50 in a million	16.3 in a million
23	Anchorage	AK	50 in a million	0.03 in a million
24	Sutter	CA	50 in a million	0.15 in a million
25	Henderson	TX	50 in a million	14.5 in a million

Show all 25Show fewer

AirToxScreen is EPA's screening estimate of the added lifetime cancer risk from breathing outdoor air toxics, modeled for the year shown. A risk of 30 in a million means that, if 1 million people breathed this air for 70 years, about 30 more might get cancer than otherwise. The estimates are averages for the population of an area, not measurements, and they do not cover indoor air, diesel particulate matter or other exposures. EPA rounds the total risk to one or two significant figures; the source and pollutant numbers are unrounded, so they do not always add up to the total. EPA advises against using these results to compare places or to judge risk for one person.

Frequently asked questions

What does a cancer risk of 30 in a million mean?: It is EPA's modeled estimate that about 30 out of every 1 million people breathing the outdoor air at that level for a lifetime could develop cancer because of air toxics. It is a screening estimate for a population, not a prediction for any one person.
Why is background such a large share?: Background is the risk from pollutants that have been in the air for a long time or come from far away, such as carbon tetrachloride. It is about the same everywhere, so local differences come mostly from the other sources.
Is AirToxScreen the same as the old NATA?: Yes. AirToxScreen replaced the National Air Toxics Assessment (NATA) and uses updated emissions and modeling.

Source: U.S. Environmental Protection Agency, AirToxScreen 2020 · Last updated 12/31/2020

AirToxScreen (Air Toxics Screening Assessment)U.S. Environmental Protection Agency · Official site

Data as of 12/31/2020

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Where the risk comes from, nationwide

Estimated lifetime cancer risk per million people, by type of source

Formed in the air (secondary)17 in a million55.9%
Background2.9 in a million9.5%
Residential wood burning2 in a million6.5%
Natural vegetation (biogenic)1.8 in a million6.0%
Small and area sources (nonpoint)1.7 in a million5.5%
Cars, trucks and buses1.5 in a million4.9%
Nonroad engines, ships, trains and airports1.4 in a million4.7%
Wildfires and prescribed fires1.1 in a million3.6%
Industrial and other stationary point sources1.1 in a million3.5%

Related data

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