rom Vital and Health Statistics of the National Center for Health Statistics 

Blood Carbon Monoxide Levels in Persons 3=7 

United States, 1976-80a 

by Edward P. Radford, M. D., University of Pittsburgh and Terence A. Drizd, Division of Health Examination Statistics 

Air pollution is an often-cited environmental hazard in many cities of the United States. One major 

component of air pollution is carbon monoxide, an 

odorless colorless gas that is a product of incomplete 

combustion. It is one of the pollutants subject to control by the Environmental Protection Agency (EPA) 

under the Clean Air Act. National Ambient Air Quality Standards established by EPA allow a carbon 

monoxide concentration of 9 parts per million. At 

this concentration, 8 hours of exposure would generally result in blood carbon monoxide levels in humans 

greater than 1.5 percent. 

Industrial plants, electric generating plants, and 

tomobile exhausts are sources of carbon monoxide 

outdoor air. In homes, gas stoves or furnaces pro­

@ ce this gas. Tobacco smokers are regularly exposed 

to higher levels of carbon monoxide than almost all 

nonsmokers. 

The health effects of exposure to carbon 

monoxide are not fully known. However, research 

findings in selected population groups indicate that 

carbon monoxide acts as an added stress factor to 

precipitate cardiac symptomatology or episodes in 

persons with hearts already compromised by 

coronary disease.1Y2Additionally, excessive levels of 

carbon monoxide in the blood have been found by 

some investigators to impair certain perceptual and 

motor functions.1 However, further assessment of 

the possible deleterious health effects of exposure to 

carbon monoxide has been handicapped by the lack 

of data for the United States population on the body 

burden resulting from exposure. This report presents 

aThe laboratory analysis of blood carboxyhemoglobin levels was carried 

out under the direction and supervision of Edward P. Radford, M.D., 

Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh, under funding from the U.S. Department of 

Energy (contract #DE-AC02-77EV04552). Cooperation also was received from Dr. F. Lee Rodkey and hlr. R. Robertson of the National 

Naval Medical Research Institute in Bethesda. Marvland. who aided in 

equality control and validation of repo’rted _carboxyhemoglobin 

the initial findings from such data–the first estimates 

of blood carbon monoxide levels ever obtained on a 

representative sample of the U.S. population. These 

findings should also be pertinent in consideration of 

national legislation such as revision of the Clean Air 

Act and local ordinances to curb air pollution. 

Carbon monoxide is unique among air pollutants 

in that the degree of body burden from exposure to 

this gas can be directly determined by measuring the 

percent of carboxyhemoglobin (the compound 

formed from hemoglobin on exposure to carbon 

monoxide) in the blood. Blood carboxyhemoglobin 

(COHb) levels were measured on a cross-sectional national probability sample of persons representative of 

the U.S. civilian noninstitutionalized population 3-74 

years of age in the second National Health and Nutrition Examination Survey (NHANES II) conducted 

from February 1976 to February 1980. NHANES II 

is the fifth in a series of National Health Examination 

Surveys conducted since 1960 by the National 

Center for Health Statistics. These programs, 

described in previous publications,s-8 are designed to 

collect a broad range of morbidity data on chronic illness and related health information. The primary 

emphasis has been placed on obtaining those kinds of 

data that can be optimally collected through standardized, direct physical examination, tests, and measurements. Dietary intake and food consumption 

information also are collected to be used in the analysis of the interrelationships between nutrition and 

health status measures. 

Examinations were conducted in specially 

equipped Mobile Examination Centers (MEC’S), 

which visited 64 locations selected from 1,924 primary sampling units (PSU’S) into which the entire 

United States is divided. Each PSU is a standard 

metropolitan statistical area (SMSA), a county, or a 

group of two or three contiguous counties. The entire 

sample consisted of 27,801 persons ages 6 months-74 

years. Of these, 20,322 persons were examined-a 

U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES, Public Health Service, Office of Health Research, Statistics, and Technology 
2 

sample response rate of 73.1 percent. The findings below are based on data from a probability half-sample 

of 11,368 persons ages 3-74 years selected to receive 

the test for levels of carbon monoxide. Of these 

11,3$8 persons, 9,365 came in for examination, and 

acc&pttible COHb blood samples were obtained for 

8,411 @g@ing an item nonresponse rate of 10.2 

percent for this test. 

This report presents national estimates of the distribution of carbon monoxide levels in the blood of 

persons ages 3-74 years in the United States by age, 

smoking status, race, urbanization status of residence, 

annual family income, and season of the year. These 

findings will be described and analyzed further in a 

report in the Vital and Health Statistics series (i 

preparation). 

In this report the relative contributions of th!0 

four principal sources of carbon monoxide (smoking, 

ambient or outdoor exposures, occupational exposures, and indoor exposures) to COHb levels are examined. Of these, smoking is the most significant and , 

widespread, although in special circumstances each of 

the other contributors assumes some importance. 

o 
acklncedata 3 

Sources of data 

oample collection and COHb 

determination 

e 

At the Mobile Examination Center, venipuncture 

blood samples were drawn by the nurse. For the carboxyhemoglobin assessments, which were performed 

on a subset of examinees ages 3-74 years, at least 1 ml 

of whole blood was placed into a 2-ml Vacutainer and 

refrigerated until a weekly shipment was made to the 

laboratory at the University of Pittsburgh. The specimens were kept cool, but not frozen. in transit. 

Carboxyhemoglobin and methemoglobin (metHb) 

level measurements were made by the spectrophotometric method of Small et al.g This method utilizes 

the difference in light absorption spectra among 

oxyhemoglobin, carboxyhemoglobin, and methemoglobin to identify and quantify the proportions of 

these compounds in the blood. From blood diluted 

about 1 to 70 in dilute ammonia, absorbance measurements are made in the Soret region (390-435 nm) 

at four wavelengths lwith a 1-mm light path; the 

equipment employed was a Gilford Model 240 

spectrophotometer, with corrections applied to compensate for nonlinearity of the phototube. A series of 

simultaneous equations is used to determine the 

cents of carboxyhemoglobin and methemoglobin 

, by difference, the percent of oxyhemoglobin. 

easurements have been shown to be accurate and 

reliable at all levels of carbon monoxide saturation, 

including saturation from O to 5 percent COHb (see 

Technical notes), the range found to be least reliable 

when monitored with other rapid techniques. 

Simultaneous measurement of methemoglobin 

level facilitates a determination of the condition of 

the blood sample, because an excessively high methemoglobin level indicates that the sample is partiaIly 

decomposed. In this report, acceptable samples were 

defined as having methemoglobin levels of 5 percent 

or less. 

Questionnaire and demographic data 

Age was defined as age at Iast birthday at the time 

of the househoId interview. Race was determined by 

interviewer observation during the interview. The 

interviewer categorized respondents as “white, ” 

“blackj’ or “other.” Data on other races are not presented separately in this report but are included in 

the “all races” catego~. Income was defined as reported total family income during the 12 months preceding the interview. 

Based on a preliminary analysis, two season categories were defined. The fust category includes data 

for all persons in the sample examined during May 

through September; the second category includes 

data for all persons in the sample examined during 

November through March. October and April were 

transition months, and inclusion of data for persons 

in the sample examined during these months with 

those in the season categories they preceded had an 

insignificant effect on the overall means. Consequently, these data were excluded from the seasonaI 

analysis. 

Smoking status was derived from questionnaire 

data collected on all respondents ages 12-74 years. 

Never-smokers were defined as persons who had 

smoked fewer than 100 cigarettes in their lifetimes 

and were not current smokers. Ex-smokers were persons who had smoked more than 100 cigarettes but 

were not current smokers; ex-cigar and ex-pipe smokers were not identified separately but were included 

in the never-, ex-, or current smoker category, depending on their cigarette smoking status. Current 

smokers were persons reporting that the y were current cigarette, cigar, or pipe smokers. 
4 

Results 

In all the following analyses, the primary statistics 

of interest are the mean COHb levels for the population subgroup or the proportion of the subgroup with 

blood COHb levels greater than 1.5 or 2.0 percent. 

The sample sizes for most of the defined subgroups 

were large enough to provide national estimates that 

are not subject to excessive sampling variability. Unless otherwise noted, statistical significance was 

determined at the 5-percent level, as described in the 

Technical notes. The tables at the end of the text also 

present population frequency distributions for COHb 

(from which can be determined the proportion of the 

population with COHb levels greater than critical 

points other than the 1.5 or 2.0 percent used in this 

report) and selected p.krcentiles. 

Carboxyhemoglobin concentration by 

smoking status and age group 

Table 1 and figure 1 show the mean percent of 

carboxyhemoglobin concentration in blood among 

the U.S. population ages 3-74 years by smoking status 

and age. Children in the age group 3-11 years were 

assumed to have never smoked, although among the 

1.2 percent of the population with COHb levels 

greater than 2 percent in this age group, a few smok5 ~ Confidence intervals 

ers may have been present. For healthy nonsmokers,@ 

2 percent is well above the sum of COHb arising from 

endogenous metabolism and from minimal exposures 

to ambient CO. For this reason, values greater than 2 

percent were considered to be the result of unusual , 

exposures. About 1 percent of the children under 5 

years of age had COHb levels greater than 2 percent, 

and it is likely that most of these cases represent exposures to sources other than smoking. 

&nong never-smokers age 12 years and over, 3.6 

percent had COHb levels greater than 2 percent (figure 2). The difference between age groups of neversmokers may be due to occupational exposures of the 

older group to environments with high ambient CO 

levels (such as those experienced by garage mechanics 

or taxi drivers). 

The ex-smoking population show 5.5 percent 

with COHb levels greater than 2 percent, comp~ed 

with 3.6 percent for never-smokers age 12 years and 

over. The higher proportion with COHb levels over 2 

percent accounts for the higher mean and standard ‘ 

deviation for ex-smolcers than for never-smokers, because the two medians are nearly identical (0.77 percent COHb versus 0.74 percent COHb, respectively 

The excess may be accounted for in part or wholly 

the inclusion in the ex-smoking group of smok b 

100 ~ Confidence intervals 

80 

4 

60 

3 1111

40 

2 

20 

1 

0 

0 All Never- Ex-smokers Current 

All Never- Ex-smokers Current statuses smokers smokers 

statuses smokers smokers 

Smoking status 

Smoking status a 

Figure 2. Percent of sample above 2 percent COHb concentration for 

Figure 1. Mean blood COHb concentration for persons 12-74 years of persons 12-74 years of age, by smoking status: United States, 

age, by smoking status: United States, 1976-80 1976-80 
----

� who incorrectly reported a history of having stopped 

smoking. Incorrect reporting appears to be a particular problem among older teenagers. 

The expected effect of smoking on COHb levels 

was shown clearly (figure 3), but it is of interest that 

9.1 percent of the current smokers had COHb Ievels 

of 1 percent or less–within the usual range for neversmokers. While the prohibition against smoking in the 

examination unit may have resulted in lower COHb 

levels for some smokers, especially for those examined in the morning, this group with low values 

clearly cannot be inhaling much of their own cigarette smoke. Analysis by smoking level, which is not 

sho,wn in this report, indicated that light smokers (1-5 

cigarettes per day) contributed many of these low 

values. 

The smoking population showed a mean COHb 

level of more than 4 percent; for never-smokers, the 

mean was less than 1 percent. The standard error for 

the smoking group was more than three times as large 

as that for the never-smoking group. The large 

variability of COHb levels for the smoking group, 

along with the relative insensitivity of this group to 

an incremental change in the environmental burden 

of CO when compared with the never-smoking group, 

made it necessarv. to limit subsequent analvses . of

Neversmokers 

\ 

100- \ / —- —-

//0 --~-& 

‘/ 

90 -

/

[ /

Ex-smokers 

80 -/ 

/ Current 

70 -1 smokers 

J’ \ 

60 -/ 

50 

/ 

40 :/ 

30 

20 I 

10 

/,,,,,,

0 

012345678 9 10 

Percent COHb concentration 

I 

Figure 3. Cumulative distribution of percent COHb concentration for 

persons 12-74 years of age, by’ smoking status: United States, 

1976-80 

akmxkta5 

demographic and environmental factors to the neversmoking subjects. For the one-third of the age 12 or 

over population that smokes, the subtle effects of 

environmental sources of CO are overwhelmed by the 

massive impact of smoking. 

COHb concentrations for never-smokers 

by race and urbanization 

The COHb levels for persons in the never-smoked 

category are shown in table 2 and figure 4 by urbanization, age, and race. The four urbanization classes 

used, based primarily on the population of the standard metropolitan statistical area (SMSA) in which the 

individuals resided, were: (1) population over 

1,000,000, central city; (2) population over 

1,000,000, not in the central city; (3) population 

under 1,000,000; and (4) rural. In some subsets, the 

numbers of subjects were small (especially among 

black persons), but the numbers are generally sufficient to permit reliable comparisons. 

Several conclusions are apparent from table 2. 

First, among children ages 3-11 years, the mean 

COHb level is statistically significantly higher for 

those in large cities than for those in smaller cities 

and rural areas (mean difference of 0.27, P < 0.01). 

Central city children especially show higher values, 

with a mean difference of 0.19 percent COHb between those in the central city and those not in the 

central city; a further mean difference of less than 

0.10 percent COHb was found between children 

living in the large cities but outside the central city 

and those in the smaller SMSA’S or rural areas. These 

differences, however, are not physiologically significant and are in the reported range of variation of 

endogenous COHb production. 10 The proportion of 

the population with COHb levels greater than 2 percent does not vary systematically with degree of 

urbanization. These observations are very similar to 

those reported by Kahn et al. in their study of St. 

Louis, Me., adults.11 There is little indication that 

white and black children differ in mean COHb to any 

significant extent, although black children are 

observed to have slightly higher values in general. 

Second, the urban-rural gradient is somewhat 

greater for adult never-smokers than for children, although it is still small (a mean difference of about 

0.4 percent COHb). Confounding by occupational 

exposures to CO among adults may contribute to the 

larger urban-rural gradient. 

Black adults were observed to have consistently 

higher COHb levels than white adults. This probably 

also is explained by greater likelihood of occupational 

exposure among black adults. Among white adults in 

the central city of SMSA’S with over 1,000,000 

population, 5.7 percent had COHb’levels greater than 

2 percent: the corresponding figure for black adults 

was 8.6 percent. 
6


m Population more than 1,000,000, central city


~ Population more than 1,000,000, not central city


~ Population less than 1,000,000


~ Rural


1.6 — I Confidence intervals 

1.5 

1,4 

1.3 I-h 

1.2 “ 

-f- T 1.1 rh- - 1.0 

0.9 l-h. T T 

0.8 1-

0.7 

0.6 

0.5 -

0.4 -

0.3 

0.2 

0.1 

0.0 _ 

White, 3-11 years Black, 3-11 years White, 12-74 years Black, 12-74 years 

Race, age, and level of urbanization 

Figure 4. Mean blood COHb concentration for never-smokers 3-74 years of age by race, age, and level of urbanization: United States, 1976-80 

I 

e 
——sdata 7’ 

The conclusions drawn above mask, to a large 

extent, the variability observed among locations. A1-

though the design for NHANES II does not provide 

samples representative of the individual selected 

SMSA’S, an examination of the proportion of the 

population with COHb levels greater than 1.5 percentb by sample PSU reveals striking differences, even 

within a single urbanization class. For instance, in the 

selected locations in SMSA’S over 1 million population, this measure varies from a minimum of 2.4 percent to a maximum of 47.3 percent. This locationby-location variability will be examined in more 

�

detaiI in a subsequent report. 

In summary, analysis of carboxyhemoglobin by 

degree of urbanization shows an urban-rural gradient 

for children and adults. The results for adults also 

may be affected by occupational exposures, apparently to a greater extent among bIack persons. 

COHb concentrations for never-smokers 

by season and urbanization 

Table 3 and figures 5 and 6 show the results for 

adult never-smokers and children by the season during which the blood was drawn. The urban-rural comparisons mentioned above are retained. As described 

in the Technical notes, itineraries of MEC’S were de­

“gned to sample examinees in the more northern 

ts of the United States in the summer and in the 

m	 more southern parts of the United States in the 

winter, thus mitigating the effects of the severest 

winter weather on COHb levels. Thus this sample 

does not provide precisely representative U.S. seasonal estimates. 

Table 3 shows there is a significant effect of 

season on COHb concentration; values found during 

the summer months were about 0.3 percent COHb 

lower than those found in the winter for children and 

adults. The mean values are reflections primarily of 

the proportion of persons studied who had a COHb 

concentration more than 2 percent, and the seasonal 

difference may be ascribed largely to the fraction of 

persons with these higher values. The increased proportion of high COHb values observed in the winter 

months probably arises from indoor sources of CO, 

which are more important in winter, when homes are 

closed. Outdoor sources, especially in the urbanized 

areas, also may contribute to high COHb levels because of higher CO emissions in winter. 

Indoor sources can include gas stoves, furnaces 

and other appliances, as well as possible effects of 

passive smoking. Separate analyses of NHANES data 

ot presented in this report indicate that subjects 

g in dwellings in which the primary heating sys­

* 

bl.5 percent is used here as the upper limit for COHb in the absence of 

ambient sources of CO (see section titled “Discussion”). 

tern was unvented space heaters (n=208) had significantly higher mean COHb levels than subjects reporting electric heating (1.06 percent COHb versus 0.74 

percent COHb). These results support the hypothesis 

that subjects using unvented or portable space heaters 

are more likely to have a significant indoor exposure 

to CO, a reasonable conclusion given present knowledge regarding the likelihood of CO release from 

these units into living space. 

One indication of the possible contribution of indoor sources is the significantly higher proportion of 

never-smokers with COHb concentrations greater 

than 2 percent found in the winter months(P<0.01). 

For children aged 3-11 years, 2.9 percent had levels 

more than 2 percent COHb in November through 

March, compared with none in the summer; for 

adults, 5.4 percent had levels greater than 2 percent 

COHb in the winter, compared with 1.6 percent in 

the summer. 

The urban-rural gradient persists and is similar for 

both seasons, at least for children, which confh-rns the 

likelihood that this gradient is derived primarily from 

exposure to ambient (outdoor) sources of CO. There 

may be a slight additiomd seasonal effect on adults in 

large urban central cities, but this effect does not 

appear to be large. The urban-rural difference could 

be due to greater occupational exposures in winter 

for persons in urban areas. 

COHb concentrations for never-smokers 

by income and urbanization 

BIood carboxyhemoglobin Ievel,s among the 

never-smoking group were analyzed by family income 

classification. Table 4 and figure 7 show the results 

of this evaluation by urbanization category. In general, the results showed that individuals in the lowest 

family income category (Iess than $10,000) had 

somewhat higher COHb levels than those in other 

income groups. However, the effect of family income 

was greatest and most clear for children ages 3-11 

years. In terms of the percent of the population of 

children with COHb levels greater than 2 percent, 

there were 2.7 percent in the lowest income category, 

0.9 percent in the middle income category, and none 

in the highest income category, when aIl urbanization 

categories were combined. 

This income effect was observed in all four urbanization classes. In every category, the mean COHb 

level for children ages 3-11 years was highest for 

those in families whose income was less than 

$10,000, and the mean COHb level tended to decrease as income category increased. This trend was 

attributed primarily to indoor sources of CO because 

the other sources of CO either were eliminated (as in 

the case of smoking and occupational sources) or held 

constant (as in the case of outdoor sources) in this 
8 achancedata 1 

1.4 

1.3 

1.2 

1.1 

1.0 

0.9 

0.8 

m Population more than 1,000,000, central city 

m Population more than 1,000,000, noncentral city 

~ population less than 1,000,000 

~ Rural 

I Confidence intervals 

i. 

.T T 

T 

0.7 T 

0.6 

1- 0.5 

0,4 

0.3 

0<2 

0.1 

0.0 

Summer, 3-11 years Winter, 3-11 years Summar, 12-74 yeers Winter, 12-74 yeers 

Season, age, and level of u rbanization 

Figure 5, Mean blood CHOb concentration for ,never-smokers 3-74 years of age, by season of sample collection, age, and Iavel of urbanization: / United States, 1976-80 
admceMa9 

—1 

13 

12 

11 

10 

9 

8 

7 

6 

5 

4 

3 

2 

1 

0 s 

Summer, 3-11 yeers 

m Population more than 1,000,000, central city 

~ Population more than 1,000,000, noncentral city 

~ Population lessthan 1,000,000 

~ Rural 

~ Confidence intervals 

. 

. 

T 

A -il-ib-


Winter, 3-11 years Winter, 12-74 years 

Season, age, and level of urbanization 

Figure 6. Percent of sample above 2 percent COHb for never-smokers 3-74 years of age, by season of sample collection, age, and level of 

urbanization: United States, 1976-80 

G 
\/

. 

k 

. 

1.4 

1.3 

1.2 

1.1 T1-

1.0 

0.9 

0.8 T 

0.7 T 

0.6 

0.5 

I 

0.4 ~ 

. 

.’ 

0.3 

\ 

. 

I 0.2 i 

\ 

,, 

0.1 / 

‘-

\ 

. 0.0 

m More than 1,000,000, cantral city 

~ More than 1,000,000, not central city 

~ Less than 1,000,000 

~ Rural 

~ Confidence intervals 

ltl T 

T — T 

I

.

;\la 

/I 

. 

;/ 

i­

‘/ 

1-

!> 

Less than $10,000 $10,000-19,999 $20,000 or more Lass than $10,000 $10,000-19,999 $20,000 or more 

3-11 years 3-11 years 3-11 years 12-74 years 12-74 yaars 12-74 years 

I Family income, age, and level of urbanization 

1-

mFigure 7. Mean blood COHb concentration for naver-smokers 3-74 years of age, @ “Iy income, age, and level of urbanization: United States, 1976-80 �

amcdata 11


,. +.analysis. The observed income effect suggests that the mean COHb level for subjects in the lowest 

:conomic status is a major factor in the likelihood of income group was highest in every urbanization catesignificant exposure to CO in the home environment. gory, none of the differences was statistically signifiFor adults, the differences of COHb level by in- cant. These results are similar to those of Kahn 

come category were not striking, despite the fact that et al.,l 1 who also were not able to substantiate a relain their case occupational exposures may have con- tionship between family income and COHb level 

tributed to higher levels that were found. Although among adults. 

/----

,-----
12


Discussion 

Clearlyj smoking constitutes the greatest source 

of exposure to carbon monoxide; the mean COHb 

level for smokers was more than four times the level 

for never-smokers, and the smoking effect completely 

overwhelmed the much more subtle contributions of 

indoor and ambient sources. In addition, adults who 

reported a history as ex-smokers may include some 

current smokers, and some adult never-smokers may 

have COHb levels more than 2 percent as a result of 

occupational exposures to CO. 

The only population subgroup not subject to the 

possible confounding effects of smoking or occupational exposures is children ages 3-11. Their results 

were used to assess the contribution of indoor or 

ambient CO. The results of children in this age group 

(mean COHb of 0.73 percent) indicate that, on the 

average, exposures to ambient CO have been well 

below the current ambient standard of nine parts per 

million, an air concentration at which 8 hours of 

exposure generally would result in a COHb level more 

than 1.5 percent.1 

Although a mean difference of 0.27 percent 

COHb was found between central cities and rural 

areas, most urban areas showed little evidence of 

ambient exposures leading to blood COHb levels 

greater than 1.5 percent. Nevertheless, in some large 

metropolitan areas, substantial elevations of CO in 

blood were observed. Moreover, by chance, no sampling locations were in cities at high altitudes, where 

outdoor CO emissions are likely to be more important than at sea level. 12 

The analysis of the seasonal changes in COHb 

,-

levels in children indicates that in winter, especially in 

central city urban areas, a significant fraction is exposed to CO, causing levels of COHb in excess of 2 

percent. This CO exposure probably is explained by 

indoor sources, such as improperly adjusted or vented 

heating or cooking units. Some contribution from 

outdoor sources or passive smoking (inhalation of 

ambient tobacco smoke products) also may be 

present. 

The evidence of possible elevated indoor exposures to CO may be significant. If the results for children are extrapolated to the entire U.S. population, 

the fact that 2 percent or more may be exposed during the winter to indoor sources of CO in excess of 

the outdoor ambient standard (nine parts per million) 

emerges as a potential public health problem. 

These observations differ from those reported by 

Stewart et al.,l 3 who measured COHb in blood samples obtained from blood donor centers in several 

communities in the United States. These investigators 

found that for all urban and rural communities, a 

significant fraction of samples obtained from nonsmokers showed levels of COHb greater than 1.5 percent. Although NHANES II found similar evidence_, 

of exposure to outdoor CO in a few urban location 

in general, the values observed in this study were nc 

indicative of physiologically important exposures 

from outdoor sources. The results presented in this 

report are consistent with measurements made on 

nonsmoking controls by other investigators in various 

regions of the country.l!ll~lo~ls 
aklcdaa 13


0 

References 

1Carbon Monoxide. Report to the Committee on Medical and 9 Small, K. A., Radford, E. P., Frazier, J. .M., and others: A


Biologic Effects of Environmental Pollutants. Washington. rapid method for simultaneous measurement of carboxy-and-


National Academy of Sciences Press, 1977. methemoglobin in blood. J. AppL PhysioL 31:154-160, 1971.


2 Coronary Drug Project Research Group: Factors influencing 10Cobum, R. F., Forster, R. E., Kane, P. B.: Considerations


long-term prognosis after recovery from myocardial infarc- of the physiological variables that determine the blood car­


tion–three-year findings of the coronary drug project. boxyhemoglobin concentration in man. J. Clin. Invest.


J. Chronic Dis. 27:267-285, 1974. 44:1899-1910, 1965.


3 National Center for Health Statistics: Plan and initial pro- 11 Kahn, A., Rutledge, R. B., Davis, G. L., and others:


gram of the Health Examination Survey. Vital and Health Sta- Carboxyhemoglobin sources in the metropolitan St. Louis


tistics. PHS Pub. No. 1000-Series l-No. 4. Public Health population. Arch. Environ. Health 29:112-135, 1974.


Service. Washington. U.S. Government Printing Office, July 12Carbon Monoxide in People of Denver. Orleans, M. and


1965. White, G. F., eds. University of Colorado Environmental


4 NationaJ Center for Health Statistics: PlarI, operation, and Council. University of Colorado Institute of Behavioral


response results of a program of children’s examinations. Vital Sciences. Denver, 1974.


and Health Statistics. PHS Pub. No. 1000-Senes l-No. 5. 13 Stewart, R. D., Baretta, E. D., Platte, L. R., and others:


Public Health Service. Washington. U.S. Government Printing Carboxyhemoglobin levels in American blood donors. JAM4.


Office, Oct. 1967. 229:1187-1195, 1974.


5 National Center for Health Statistics: Plan and operation of 14 Aronow, W. S., Harris, C. N., Isbell, M. W., and others:
 a health examination survey of U.S. youths, 12-17 years of Effect of freeway travel on angina pectoris. Ann. Intern. Med.


age. Vital and Health Statistics. PHS Pub. No. 1000-Series 1- 77:669-676, 1972.


No. 8. Public Health Service. Washington. U.S. Government


Printing Office, Sept. 1969. “15Ayres, S. M., Gianelli, Jr., S., and Mueller, H.: Effect of low


concentrations of carbon monoxide. Part IV. Myocardial and -. .-. . —— 6 National Center for Health Statistics: Plan and operation of systemic responses to carboxyhemoglobm. Ann. NY A cad. Sci. 

the Health and Nutrition Examination Survey, United States, 174:268-293, 1970. 

1971-1973. Vital and Health Statistics. PHS Pub. No. 1000-

Series l-No. 10a and 10b. Public Health Service. Washington. 16Woodruff, R. S.: A simple method for approximating the 

U.S. Government Printing Office, Jan. 1977. variance of a complicated estimate. J. Amer. Statis. Ass. 

National Center for Health Statistics: Plan and operation of 

e the HANES I Augmentation Survey of Adults 25-74 years, 17National Center for Health Statistics: ~suedo-replication: 

United States, 1974-75. Vital and Health Statistics. PHS Pub. Further evaluation and application of the brdanced half-sample 

No. 1000-Series I-No. 14. Public Health Service. Washington. technique. Vital and Health Statistics. PHS Pub. No. 1000-

U.S. Government Printing Office, June 1978. Series 2-No. 31. Public Health Service. Washingtcin. U.S. Gov8 National Center for Health Statistics: Plan and operation of ernment Printing Office, Jan. 1969. 

the second National Health and Nutrition Examination 18 Collison, H. A., Rodkey, F. L., and O’Neal, J. D. DeterSurvey, 1976-1980. Vital and Health Statistics. PHS Pub. No. mination of carbon monoxide in blood by gas chromatog1000-Series l-No. 15. Public Health Service. Washington. U.S. raphy. Clin. Chem. 14:162-171, 1968. 

66:411414, 1971. 

Government Printing Office, July 1981. 
14 acharxedata


Table 1.Percent carboxyhemoglobin by as and smoking status–scmple sizes, weighted population estimates, maans, standard deviations, standard errors, selected 

percentiles, and cumulative frequency distributions: United States, 1976-80 

Percentiles 

Smoking status and agel “2 N3 Mean Standard Standard 

deviation error 5otll 75th 90th 95th 

All smoking statuses 

3.74years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

3-n years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

12-74years, . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

Never-smokers 

3-74years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

3-n years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

12-74years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

Ex-smokers 

12-74years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

Current smokers 

12-74yeara .,........,.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

lSm~kl"g hi~t~rle~ara ""available fOrchildran less tha" lzyaa,sofqja. 

2n = unwalghtad scmpla slza. 

3N= population estimata In thousands. 

A 

9,365 

2,055 

7,310 

5,459 

2,055 

3,404 

1,366 

2,533 

195,877 1.94 2.236 

30,066 0.73 0.502 

165,612 2,16 2.358 

106,042 0.S3 0.671 

30,066 0,73 0,502 

75,976 0.87 0.726 

28,655 0.97 0.999 

61,015 4,30 2.553 

PercentCOHb 

0.037 0,91 2.38 5.49 6.83 

0.019 0.67 0.87 1.12 1.42 

0.044 1.01 3.17 5.79 7.05 

0.021 0.72 0.97 1.33 1.65 

0.019 0.67 0.87 1.12 1.42 

0.025 0.74 1.01 1.38 1.77 

0.031 0.77 1.04 1.58 2.08 

0.072 4.15 5,89 7.56 8.68 

$

admcdda 15


‘o Tablel. Percent carbOxyhemoglotin bya~andsmOking status+mple siz~, wi@tedpopulatiOn =timat=, means, standard deviations, standard erro~, selected 

percentiles, andcumulative frequerrcy distributions: United States, 1976-60-Con. 

Percent COHb 

<0.50 ~ 7.00 <1.50 <2.00 ~ 2.50 <3.00 <3.50 <4.00 <4.50 ~ 5.00 ~ 5.50 ~ 6.00 <7.00 ~ 8.00	 —<9.00 — 

< Zo.oo

Cumu Iative percent distribution of population 

16.4 55.3 68.4 72.9 75.6 78.0 80.6 83.1 85.5 87.6 90.0 92.4 95.6 97.4 98.7 99.4 

28.6 84.7 95.9 98.8 98.9 99.5 99.5 99.7 99.7 99.7 99.8 100.0 100.0 100.0 100.0 100.0 

14.2 49.9 63.4 66.2 71.4 74.1 77.2 80.1 82.9 85.4 88.3 91.0 94.8 86.9 98.4 89.2 

23.7 77.3 93.2 97.0 98.0 98.6 99.1 99.3 99.4 88.5 99.6 99.8 88.9 99.9 99.9 100.0 

28.6 84.7 95.9 98.8 98.9 99.5 99.5 99.7 99.7 99.7 99.8 100.0 100.0 100.0 100.0 100.0 

21.8 74.4 92.2 96.4 97.7 98.3 98.9 99.2 99.3 99.4 99.5 99.7 99.8 99.8 99.9 1 C@.o 

19.8 72.1 88.6 94.5 86.2 97.6 98.0 98.1 96.4 98.5 98.8 99.0 99.2 99.4 88.8 88.9 

2.1 9.1 15.7 20.8 27.1 33.1 40.4 47.9 55.4 61.9 69.4 76.5 86.6 92.0 95.9 98.0 
Table 2. Percent carboxyhemoglobin for never-smokers by age, race, and urbanization status-sample sizes, waighted population estimatas, means, standard daviaticms, standard errors, selected percenti Ies, and cumulative 

-A 

Urbanization level, race, and age of mW.W.Sm&em I 

All urbanization levels 

All racea4 

White 

3-74yeara . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

3-n years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

12-74years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

Population more than 1,000,000, cantral city 

All races 

3-74years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

3-n years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

12-74years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

White 

3-74yaars . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

3-n years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

12-74years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

81ack 

3-74years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

3-n years, . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

12-74yaars . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

Population mo~than 1,000,000, not cantral ciw 

All races 

3-74yaars . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . b 

3-n years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

12-74yaars . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

White 

3-74years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

3-n years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

12-74years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

Black 

3-74years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

3-n years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

12-74years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

frequency distribution United States, 1976-80 

Percentiles Percent COHb 

“2 A13 Mean Standard Standard 

deviation error 50th 75th 90th 95th <1.00 <1.25 <1.50 <_ 1.75 <2.00 <2.25 <2.50 

PercentCOHb Cumulative percant distribution of population 

5,459 106,042 0.83 0.671 0.021 0.72 0.97 1.33 1.65 77.3 86.4 93.2 95.7 97.0 97.5 98.0 

2,055 30,066 0.73 0.502 0.019 0.67 0.87 1.12 1.42 84.7 93.0 95.9 97.7 98.B 98.9 98.9 

3,404 75,976 0.87 0.726 0.025 0.74 1.01 1.38 1.77 74.4 86.6 92.2 94.9 96.4 97.0 97.7 

4,512 89,322 0.80 0.645 0.021 0.70 0.94 1.26 1.58 79.8 89.9 94.0 96.2 97.1 97.5 98.1 

1,628 24,563 0.71 0.504 0.021 0.65 0.85 1.09 1.40 86.2 93.6 96.0 97.8 98.8 98.9 99.0 

2,8B4 64,759 0.84 0.690 0.024 0.72 0.98 1.32 1.68 77.3 88.5 93.2 95.6 96.5 97.0 97.8 

818 13,389 1.02 0.890 0.065 0.84 1.17 1.59 1.93 64.2 78.1 87.5 92.0 95.9 96.6 96.9 

373 4,515 0.82 0.548 0.048 0.76 0.95 1.33 1.57 77.1 88.2 94.7 96.4 98.2 98.3 98.3 

445 8.875 1.12 1.012 0.079 0.91 1.31 1.77 2.03 57.7 72.9 83.9 B9.7 94.7 95.7 96.1 

629 12,151 1.11 0.691 0.045 1.02 1.31 1.69 2.02 49.5 71.2 83.6 91.0 94.8 96.0 97.1 

231 3,099 0.95 0.460 0.047 0.87 1.11 1.51 1.76 66.2 80.6 89.5 95.0 98.3 98.3 9B.3 

398 9,052 1.17 0.746 0.051 1.07 1.36 1.7B 2.22 43.7 68.0 81.5 89.6 93.6 95.2 96.7 

324 7,088 1.05 0.608 0.032 0.86 1.25 1.58 1.98 53.7 75.8 86.2 93.8 95.4 96.6 98.2 

104 1,702 0.90 0.446 0.045 0.82. 1.04 1.47 1.73 73.8 85.3 90.2 96.8 98.5 98.5 9B.5 

220 5,386 1.10 0.653 0.039 1.07 1.29 1.60 2.18 47.4 72.7 84.9 92.9 94.3 96.0 98.1 

275 4,383 1.22 0.872 0.108 1.08 1.44 1.88 2.63 44.1 63.6 77.8 85.8 93,2 94.3 94.8 

117 1,241 1.01 0.566 0.063 0.92 1.33 1.57 1.95 54.2 71.7 87.3 91.9 97.7 97.7 97.7 

158 3,142 1.31 0.863 0.129 1.11 1.51 1.84 3.20 40.2 60.4 74.0 83.4 91.4 93.0 93.6 

719 18,207 0.91 0.701 0.040 0.80 1.08 1.46 1.74 69.3 83.3 90.8 95.1 96.2 97.3 98.2 

262 5,074 0.76 0.430 0.051 0.74 0.97 1.21 1.45 78.1 90,9 85.9 99.0 99.9 99.9 99.9 

457 13,133 0.96 0.777 0.043 0.B3 1.15 1.55 2.02 65.9 80.4 86.8 93.6 94.8 96.3 97.6 

632 16,170 0.90 0.739 0.045 0.79 1.08 1.51 1.80 70.3 82.9 89.9 94.5 95.8 97.0 98.0 

228 4,458 0.74 0.449 0.055 0.69 0.97 1.2B 1.48 77.9 89.7 95.3 98.9 99.9 99.9 99.9 

404 11,712 0.86 0.817 0.047 0.83 1.12 1.66 2.03 67.4 80.3 87.8 92.8 94.2 95.8 97.3 

76 3,658 0.93 0.330 0.028 0.68 1.15 1.36 1.60 59.3 83.4 97.3 100.0 100.0 100.0 100.0 

30 515 0.83 0.287 0.052 0.84 0.92 1.16 1.17 79.7 99.1 100.0 100.0 100.0 100.0 100.0 

46 1,143 0.98 0.361 0.048 0.93 1.20 1.36 1.50 50.1 76.4 96.1 100.0 100.0 100.0 100.0 

Sae footnotes at end of table. 
ercent carboxy hemoglobin for new?r-smokers by age, race, and urbanization status—sample sizes, 

frequency distributions: United States, 1976-80–Con. 

Percerr tiles Percent COHb 

Urbanization level, race. and age of never-smokersl “2 N3 Mean Standard Standard 

deviation error 50th 75th 90th 95th <1.00 L 1.25 <1.50 ~ 1.75 ~ 2.00 <2.25 <2.50 

Population less than 1,000,000 

All races Percent CO Hb Cumulative percent distribution of POPU Iation 

3-74years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2,109 41,530 0.79 0.717 0.036 0.69 0.91 1.18 1.43 82.8 92.5 95.5 96.B 97.6 97.8 98.0 

3-n years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 811 11,816 0.70 0.602 0.042 0.65 0.82 1.06 1.21 88.1 ~ 97.4 98.2 98.4 98.7 98.7 

12-74years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ,298 29,714 0.83 0.759 0.039 0.71 0.94 1.22 1.56 80.6 94.7 96.2 97.2 97.4 97.8 

White 

3-74years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ,654 33,691 0.76 0.659 0.034 0.68 0.89 1.11 1.34 84.4 93.8 96.3 97.2 97.7 97.8 98.1 

.- 3-n years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 599 9,071 0.69 0.618 0.047 0.63 0.81 1.03 1.21 89.0 95.8 97.4 98.2 96.5 98.B 98.8 

12-74years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ,055 24,620 0.79 0.678 0.037 0.69 0.92 1.13 1.36 82.6 93.0 95.9 96.9 97.4 97.5 97.8 

Black 

3-74years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 383 5,883 0.94 1.071 0.087 0.76 0.97 1.49 1.92 77.5 85.5 90.8 93.9 96.2 96.8 97.1 

3-n years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182 2,214 0.73 0.623 0.068 0.67 0.61 1.10 1.35 87.1 94.6 96.7 97.6 97.6 97.9 97.9 

12-74years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201 3,669 1.06 1.259 0.108 0.82 1.10 1.59 1.98 71.B 80.0 87.2 91.7 95.3 96.1 96,6 

Rural 

All races 

3-74years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 #999 34,103 0.74 0.606 0.034 0.65 0.86 1.13 1.47 84.9 92.2 95.2 96.4 97.6 97.8 98.3 

3-n years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 750 10,071 0.68 0.446 0.024 0.62 0.81 1.02 1.29 89.7 94.6 96.1 97.2 98.7 98.8 98.9 

12-74years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,249 24,032 0.77 0.662 0.040 0.66 0.88 1.16 1.53 82.9 91.2 94.8 96.0 97.1 97.4 9B.O 

White 

3-74years . . X . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,899 32,321 0.74 0.610 0.035 0.65 0.85 1.12 1.44 85.4 92.5 95.4 96.5 97.6 97.7 98.2 

3-llyeirrs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 696 9,325 0.68 0.455 0.027 0.62 0.80 1.02 1.29 89.7 94.8 86.0 97.2 98.6 98.7 98.8 

12-74years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,203 22,995 0.76 0.664 0.041 0.66 0.88 1.15 1.49 83.6 91.5 95.1 96.2 97.1 97.3 98.0 

Black > 3-74years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84 1,465 0.82 0.640 0.106 0.74 0.98 1.48 1.77 76.6 85.5 92.4 93.4 97.8 98,7 9B.7 

3-llyears . . . . . . . ..c... . . . . . . . . . . . . . . . . . . . . . . . 44 544 0,74 0.419 0.085 0.72 0.94 1.28 1.28 86.8 89.7 98.3 9B.3 I 00.0 100.0 100.0 

12-74vears . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 920 0.86 0.762 0.143 0.74 1.OB 1.69 1.77 70.5 83.1 88.9 90.5 96.5 97.9 97.9 

Ismoki”g histories are unavciilable for children less than 12 Years of a90. 

%= unwe[ghta.d sample size. 

3N = pqwtationes timate In thousands. 

‘$1ncludas other racial groups in addition to whito and black. 
Table3. Permntcarboxyhemog10 tin fOrnever-smokers byage, seasOn, andurbanization status-mmple sizes, wighted population estimates, means, standard deviations, standerd errOrs, selected percentiles, andcumulativa 

frequency distributions: United States, 1976-80 

‘% Percentiles Percent COHb 

Urbanization status, season, and age of never-smokem’ “2 /lJ3 Mean Standard Standard 

deviation error 5ot/r 75th 90th 95th	 — 

<1.00 <1.25 

— <1.50 —<1.75 —<2.00 — 

<2.25 <2.50

All urbanization levels 

November-March ParcentCOHb Cumulative percent distribution of population 

3-74years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2,105 43,285 0.96 0.787 0.033 0.60 1.09 1.55 1.84 69.4 82.4 89.0 92.6 95.3 96.1 97.0 

3-n years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 795 12,4210.87 0.655 0.034 0.75 0.97 1.39 1.76 77.3 87.3 91.8 84.9 97,1 97.3 97.4 

12-74years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,310 30,665 1.00 0.835 0.037 0.83 1.14 1.59 2.07 66.1 80.5 87.9 91.9 94.6 95.6 86.9 

May-September 

3-74years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2,330 43,167 0.67 0.530 0.023 0.63 0.83 1.05 1.24 87.9 95.2 97.5 98.6 98.9 99.1 99.2 

3-n years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 881 12,372 0.58 0.327 0.024 0.57 0.77 0.93 1.07 92.5 97.7 98.9 99.5 100.0 100.0 100.0 

12-74years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,449 30,795 0.71 0.568 0.024 0.64 0.66 1.09 1.29 86.1 94.1 86.9 98.3 96.4 98.7 98.6 

Population more than 1,000,000, central city 

Novamber-March 

3-74years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 328 6,575 1.19 0,767 0.064 1.04 1.42 1.86 2.31 47.1 65.4 78.8 87.8 92.8 94.6 95.8 

3-n yeara . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105 1,626 1.01 0.565 0.071 0.85 1.29 1.63 1.95 64.5 74.6 84.6 92.6 96.7 96.7 96.7 

=7= 12-74years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223 4,947 1.25 0.647 0.073 1.11 1.45 1.94 2.31 41.4 62.3 76.9 66.2 91.5 93.9 95.5 

May-Saptember 

3-74years . . . . . . . . . . . . . . . . . . . . . . . . 165 2,879 0.86 0.377 0.029 0.82 1.11 1.26 1.52 65.4 86.4 84.4 89.0 100.0 100.0 100.0 

3-n years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76 844 0.77 0.369 0.030 0.78 0.92 1.11 1.34 80.6 94.5 96.5 96.5 100.0 100.0 100.0 

12-74years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89 2,034 0.90 0.3:3 0.034 0.85 1.15 1.29 1.52 59.1 83.0 93.5 100.0 100.0 100.0 100.0 

Population more than 1,000,000, not central city 

November-March 

3-74years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 312 8,163 0.98 0.590 0.050 0.91 1.17 1.54 1.76 61.1 78.7 68.7 84.6 96.3 98.0 99.1 

3-n years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121 2,352 0.88 0.473 0.066 0.64 1.11 1.45 1.56 66.5 83.0 91.2 97.9 99.7 99.7 99.7 

12-74years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191 5,611 1.02 0.642 0.081 0.94 1.19 1.58 2.02 58.9 76.9 87.7 93.6 95,0 97.3 98.6 

May-September 

3-74years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 289 7,145 0.78 0.826 0.066 0.68 0.89 1.20 1.58 82.9 90.7 84.6 96.6 86.8 97.5 96.0 

3-n years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102 1,936 0.62 0.350 0.058 0.65 0.84 0.99 1.07 80.2 99.0 100.0 100.0 100.0 100.0 100.0 

12-74years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187 5,207 0.83 0.936 0.070 0.70 0.93 1,42 1.59 80.1 87.6 92.6 95.3 95.6 96.6 97.3 

Population less than 1,000,000 

. .. November-March 

3-74years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 611 13,250 0.96 1.005 0.062 0.77 1.00 1.38 1.98 75.6 87.5 91.4 93.0 95.1 95.4 96.0 

3-n years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 226 3,635 0.90 0.969 0.099 0.69 0.91 1.16 1.83 80.1 91.7 94.3 84.6 95.1 95.6 95.6 

12-74years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 385 9,615 0.98 1.033 0.064 0.79 1.02 1.49 1.98 73.9 85.9 90.3 92.3 95.1 95.4 96.2 

May-Scptembar 

3-74yeara . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,075 20,147 0.67 0,460 0.027 0.64 0.84 1.04 1.20 88.8 96.1 98.1 98.9 89.1 99.3 99.4 

3-n years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 435 6,220 0.59 0.343 0.032 0.59 0.76 0.94 1.11 92.4 96.9 98.4 99.7 99.9 100.0 100.0 

12-74years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 640 13,927 0,71 0.499 0.026 0.65 0.66 1.07 1.22 87.1 95.7 97.9 98.6 98.8 99.0 99.1 

Semfootnotes at end of table. 
Tabla 3. carboxy hemoglobin fornavar-smokers byage, season, and urbanization status—sample sizes, waig population estimates, means, standard deviations, standard errors, selected percentiles, and cumulative 

frequency distributions: United States, 1976-80–COn. 

Percentiles Percent COHb 

urbanization status, season, and a~ Of never-s~Oke~i n2 A/3 Mean Standard Standard 

deviation error 50th 75th 90th 95th <1.00 <1.25 <1.50 ~ 1.75 <2.00 <2.25 <2.50 

Rural 

Ncwambar-March Parcant COHb Cumulative percent distribution of population 

3-74yaars . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 854 15,298 0.86 0.703 0.051 0.73 0.95 1.41 1.64 77.9 87.4 91.5 93.7 86.1 88.4 97.3 

3-llyaars . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 343 4,806 0.79 0.528 0.032 0.71 0.88 1.23 1.76 84.9 90.3 92.7 94.6 97.4 97.5 97.8 

12-74years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 511 10,492 0.90 0.772 0.062 0.74 1.01 1.45 1.88 74.7 88.1 91.0 93.3 95.5 95.8 97.1 

May-September 

3-74years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 798 12,944 0.58 0.471 0.025 0.56 0.73 0.91 1.03 94.3 98.1 98.8 99.1 88.3 99.3 99.3 

3-n years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 267 3,363 0.49 0,277 0.026 0.49 0.63 0.81 0.90 97.0 99.4 99.6 88.6 100.0 100.0 100.0 

12-74yaars . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 531 9,581 0.61 0.520 0.028 0.58 0.76 0.93 1.07 93.4 97.7 98.6 89.0 99.1 99.1 99.1 

lSmoking histories areunavailable forchlldran less than 12 Year$0fa9a. 

2n = u nwaighted sampla size. 

3N = p~pulation estimate in thousands. 
Table4. Percent carboxyhemOgloMn fornever-smokers byage, income, andurbanizatiOn status-Smple sizes, &ighted population estimates, means, standard deviations, smndard errors, se[ected ~rcentiles, and cumulative 

frequency distributions: United States, 1976-80 

Percentiles Percent COHb 

Urbanization status, age, and family income 1 “2 N3 Mean Standard Standard 

deviation error 50th 75th 90th 95th <1.00 <1.25 —<1.50 — 

<1.75 <2.00 <2.25 <2.50

All urbanization levels 

3-74 years Percent CO Hb Cumulative percent distribution of population 

Lassthan$l0,000 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2,153 36,114 0.91 0.799 0.031 0.76 1.03 1.41 1.85 73.5 85.3 91.5 94.2 95.9 98.7 97.2 

$10,000-19,889 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,888 36,920 0.78 0.597 0.025 0.70 0.92 1.22 1.53 80.0 90.8 94.7 97.2 97.9 98.1 98.5 

$20,0000 rm0re . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,189 28,519 0.80 0.609 0.025 0.70 0.94 1.27 1.57 79.8 89.7 94.0 96.0 97.3 97.7 96.3 

3-11 years 

Lessthrm$l O,OOO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 795 10,025 0.81 0.695 o.04f 0.71 0.92 1.31 1.71 79.3 89.0 92.8 95,5 97.3 97.6 97.7 

$10,000-19,899 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 768 11,369 0.69 0.408 0.027 0.66 0.85 1.06 1.29 87.3 94.6 97.4 98.8 99.1 99.1 99.1 

$20,0000 rm0re . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 432 7,838 0.66 0.345 0.023 0.64 0.84 I .09 1.20 68.2 95.6 97.7 99.0 100.0 100.0 100.0 

12-74 years 

Lessthan$l0,000 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,358 26,089 0.94 0.839 0.035 0.78 1.07 1.45 1.93 71.2 83.8 90.9 93.6 95.4 86.3 97.0 

$10,000-19,999 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,120 25,551 0.82 0.662 0.027 0.72 0.97 1.31 1.64 76.7 89.1 93.6 98.4 97.4 97.7 98.2 

$20,0000rm0re . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 757 20,681 0.85 0.682 0.033 0.72 0.98 1.37 1.78 76.7 87.5 92.6 94.8 88.2 96.8 97.7 

Population more than 1,rXI0,000, central city 

3-74 years 

Lassthan$lO,OOO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 331 5,622 1.16 0.779 0.047 1.05 1.35 1.73 2,38 47.1 68.3 81.9 90.3 93.6 94.5 88.1 

$10,000-19,999 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152 3,017 1.06 0.689 0.081 0.97 1.21 1.50 1.83 51.8 79.5 90.5 94.6 88.6 98.6 96.6 

$20,0000rm0re . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108 2,834 1.05 0.644 0.066 0.94 1.32 1.72 2.14 65.4 70.3 81.7 90.4 94.9 98.0 99.6 

3-11 years 

Lassthan$lO,OOO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130 1,384 1.01 0.522 0.069 0.90 1.33 1.62 1.76 56.8 74.4 65.0 93.6 98.2 98.2 88.2 

$10,000-19,999 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 726 0.95 0.508 0.074 0.87 1.04 1.33 1.51 71.9 83.4 94.7 96.1 96.1 98.1 88.1 

$20,0000rm0re . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 912 0.82 0.408 0.042 0.79 0.95 1.35 1.61 77.3 87.7 93.0 97.3 100.0 100.0 100,0 

12-74 years 

Lassthan$l0,000 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201 4,237 1.21 0.867 0.070 1.07 1.36 1.78 2.45 43.9 68.3 80.9 88.2 92.1 93.3 95.4 

$10,000-19,999 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98 2,291 1.10 0.736 0.087 1.07 1.22 1.52 1.83 45.5 78.3 89.2 94.1 88.7 96.7 86.7 

$20,0000rm0re . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70 1,921 1.16 0.570 0.083 1.08 1.45 1.66 2,18 45.0 62.0 76.3 87.1 92.4 97.1 88.4 

Population more than 1,000,000, not central city 

3.71 yaara 

Lessthan$l0,000 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195 4,527 1.01 0.988 0.070 0.84 1.11 1.47 2.03 69.1 82.6 90.0 92.7 93.7 88.4 86.4 

$10,000-19,999 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 239 5,790 0.91 0.664 0.068 0.82 1.17 1.64 1.72 66.2 79.4 89.4 95.6 97.0 97.6 98.2 

$20,0000rm0re . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 249 6,957 0.81 0.498 0.046 0.78 1.04 1.36 1.53 72.6 88.1 84.0 96.8 97.9 98.4 98.5 

3-1 years 

Lassthan$l0,000 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63 967 0.93 0.469 0.056 0.90 1.10 1.31 1.89 65.7 88.3 92.8 94.8 99.3 99.3 99.3 

$10,000-19,988 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107 2,057 0.75 0.433 0.064 0.75 0.98 1.29 1.44 77.7 88.6 95.6 100.0 100.0 100.0 100.0 

$20,0000rm0re . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84 1,822 0.69 0.407 0.051 0.67 0.92 1.13 1.45 82.8 93.7 97.5 100.0 100.0 100.0 100.0 

12-74 years 

Lassthan$l0,000 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132 3,561 1.04 1.100 0.088 0.80 1.11 1.51 2.24 70.1 60.9 89.3 92.1 92.1 95.6 95.6 

$10,WO-19,899 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132 3,732 1.00 0.742 0.089 0.90 1.26 1.68 1.97 59.8 74.3 86.0 93.2 95.4 96.2 97.2 

$20,0000rm0re . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . “165 6,135 0.86 0.523 0.049 0.83 1.05 1.41 1.66 69.0 88.1 92.7 95.6 97.1 97.9 98.3 

Sea footnotes atend of table. 
rboxyhemoglobin fm’ never-smokersby age, income, and urbanization status–sample sizes, Uighted population estimates, means, standard deviations, standard errors, selected percentiles, and cumulative 

frequency distributicms: United States, 1976-80-Con. 

Percentiles Parcarrt COHb 

Urbanization status, age, and family incomel “2 N3 Mean Standard Standard 

deviation error 50th 75th 90th 95th ~ 1.00 ~ 1.25 ~ 1.50 <1.75 <2.00 52.25 ~ 2.50 

Population lessthan 1,000,000 

3-74 years PercentCOHb Cumulative @rcant distributimr of population 

IJSS than $10,000 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 872 14,791 0.87 0.866 0.052 0.73 0.88 1.31 1.71 79.7 89.3 94.0 96.2 %.1 86.6 88.9 

$10,CKIO-19999 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 717 14,404 0.72 0.564 0.033 0.63 0.66 1.08 1.26 85,4 94.9 86.6 98.4 99.1 59.2 88.3 

$20,0000rm0re . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 441 10,728 0.78 0.738 0.055 0.67 0.80 1.14 1.36 64.3 93.8 95.7 86.5 97.2 97.2 97.6 

3-11 years 

Lassthan $10,WO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 331 4,291 0.79 0.918 0.092 0.67 0.84 1.10 1.57 85.1 92.2 84.7 88.2 96.2 88.8 %3.8 

$10,OOO-I9,999 . . . . . . . . . . . . . . . . . . . . . . . , . . . . . . . . . . . . . . 288 4,528 0.64 0.350 0.027 0.84 0.80 0.98 1.16 91.1 97.3 98.2 98.9 89.5 99.5 89.5 

$20,W00rmora . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161 2,777 0.63 0.316 0.039 0.63 0.60 1.05 1.16 89.4 98.3 1W.o 100.0 100.0 100.0 100.0 

12-74 years 

Lesstftan $10,000 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 541 10,500 0.90 0.880 0.053 0.76 0.98 1.34 1.81 77.5 86.2 93.7 84.8 88.1 96.6 $%.9 

$lo,wo-19@9 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 418 9,875 0.76 0.636 0.039 0.69 0,69 1.10 1.31 82.8 93.8 95.9 98.1 98.9 99.0 99.2 

$20,0000rmore . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 280 7,952 0.83 0.837 0.067 0.69 0.93 1.16 1,57 82.5 92.2 84.2 95.3 86.2 86.2 96.7 

Rural 

3-74 years 

LESSthan $10,000 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 755 11,174 0.78 0.654 0.054 0.68 0,92 1.29 1.71 80.2 89.6 93.5 95.3 97.7 97.9 98.6 

$lo,ooo-19~ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . , . , . , 779 13,689 0.73 0.602 0.032 0.65 0,84 1.07 1,36 86.3 93.8 95.9 97.1 97.4 97.6 98.2 

$30,0000rm0re . . . . . . . . . . . . . . . . . . . . . . , . . 0 . . , , . . . , . . . 390 7,994 0.72 0.580 0.031 0.63 0.82 1.08 1.39 86,6 92.7 88.1 96.5 97.7 97.7 97.9 

3-11 years 

Lessthan $10,000 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271 3,363 0.73 0.528 0.036 0.84 0.85 1.13 1.71 64.9 91.2 93.7 95.7 97.7 97.8 98.2 

$lo,ooo-19/989 . . . . . . ...!.. . . . . . . . . . . . ...0... . . . . . . . . 308 4,057 0.67 0.450 0.036 0.63 0.80 0.98 1.06 80.7 88.6 97.9 98.6 96.6 98,8 98.6 

$20,0000rmore . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148 2,322 0.60 0.327 0.028 0.60 0.74 0.88 0.92 95.3 97.1 9741 97.7 100.0 100.0 1M.o 

12-74 years 

Lessthan $10,000 . . . . . , , . 0 . . . , . . . . , . . . . . . . . . . . . . . . . . . 484 7,791 0.80 0.708 0.066 0.69 0.84 1,30 1.71 78.2 68,8 93.5 95.1 97.6 98.0 88.8 

$10,000-19988 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 471 9,632 0.75 0.657 0.035 0.88 0.88 1.14 1.47 84.4 92.6 95.1 88.6 96.8 97.1 97.9 

$20,0000rmore . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 242 5,673 0.76 0.663 0.046 0.65 0.87 1.17 1.42 86.1 90,8 95.6 88.1 88.7 88.7 97.0 

ls~~ki”g hi~~~rj~s ~r~ “~”~il~bla frr~ child,e” k,s$than 12 yaars of age. 

2n = u nwdghtad sample size. 

3N = population astimate In thousands. 
22 adtamedata 

Technical notes 

Sample design 

The information presented in this report is based 

on data from the direct standardized physical examinations, tests, measurements, and questionnaires collected in the second National Health and Nutrition 

Examination Survey during 1976-80. The target 

population of NHANES II encompassed the civilian 

noninstitutionalized population of the United States, 

including Alaska and Hawaii, of persons 6 months 

through 74 years of age. 

NHANES II utilized a multistage probability design that involved selection of PSU’S, segments 

(clusters of households) within PSU’S, households, 

eligible persons, and finally sample persons. The sample design provided for oversampling among persons 6 

months-5 years, persons 60-74 years of age, and persons living in poverty areas. The U.S. Bureau of the 

Census, under contract to the National Center for 

Health Statistics, selected, according to rigorous 

specifications, the NHANES II sample of 27,801 persons. Of this total sample, 20,322 (73.1 percent) were 

examined. A half-sample of persons 3-74 years of age 

was assigned to receive the test for levels of carbon 

monoxide. Of the 11,368 persons originally selected 

in the sample to receive the carbon monoxide test, 

9,365 came in for examination, and acceptable blood 

samples were analyzed for 8,411. 

The data in this report are presented as population estimates. Examination findings for each sample 

person have been inflated by the reciprocal of the 

probability of selecting a person, adjusted for persons 

who were not examined, and poststratified so that 

final extimates closely approximate the independent 

U.S. Bureau of the Census estimates for the civilian 

noninstitutionalized population of the United States 

by race, sex, and age as of the midpoint of the study, 

March 1, 1978. 

Adjustment for item nonresponse 

Carboxyhemoglobin and methemoglobin values 

were imputed for the 954 cases with no or unacceptable samples. The procedure used has been described 

as a “hot deck” process; in which the acceptable 

values for a case that matches the missing case on a 

number of key criteria are imputed to the case with 

missing data. For this study, the criteria on which the 

cases were required to match were smoking status, 

age group, race, and location. (Although certain locations were visited twice, each visit was assigned a 

uniqu~ number, so that matching on examination 

location had the effect of adjusting for both season 

and degree of urbanization.) Comparison of imputed 

and nonirnputed data revealed no substantial changes 

in detailed means. 

Estimation of standard errors 

o’ Because the statistics presented in the text and 

detailed tables of this report are national estimates 

based on a sample, they differ somewhat from the 

figures that would have been obtained if the survey 

had been conducted on the complete population. In 

other words, the statistics are subject to sampling 

vanability. 

The standard errors presented in tables 1-4 are 

primarily a measure of sampling variability, but they 

also include the variation that arises in the measurement process, usually called measurement error. 

These standard errors were calculated using a Taylor 

Series linearization method.1 G This process approximates the variance of nonlinear (or linear) statistics, 

for example, means and proportions, using the first 

two terms of a Taylor Series expansion. If the higher 

order terms of the expansion are negligible and the 

sample is of a reasonable size for the domains of 

interest, then this approximation provides variance 

estimates as reliable as those from the pseudoreplication method adapted for use in the analyses of 

NHANES 11 data.lT Estimates of standard errors are 

themselves subject to errors that may be large if the 

number of cases or PSU’S on which the estimates are 

based is small. 

Statistical significance was determined usin!0 

z-tests when individual subgroup statistics were compared and using a modified chi-square technique 

when testing for effects. Both methods were modified 

to incorporate the complex NHANES II sample 

design. 

Carboxyhemoglobin quality control 

Three procedures were employed in the laboratory to ensure validity and reliability of the spectrophotometric method and to maintain the necessary 

quality control on the laboratory determinations: 

(1) duplicate determinations on “blind” and arbitrarily selected samples using a completely different 

method of measurement, (2) duplicate measurements 

on every sample, and (3) regular determinations using 

Small’s method and comparisons with previous values 

on an independent group of nonsmoking subjects 

whose COHb levels would be expected to be. very 

stable. The first procedure provided a measure of the 

validity of the spectrophotometric method and was 

essential to detect any baseline drift, a significant 

problem when measuring low COHb concentrations 

by spectrophotometry. The second and third pr 

cedures provided measures of precision and esta 

lished the reliability of the final raw data. m 

The validity of the spectrophotometric method 

was verified by a comparison of results obtained by 
dmcdata 23 

e 

e 

Small’s method with those obtained using the more 

accurate and precise (but prohibitively costly and 

ime-consuming) gas chromatography method. At 

gular intervals, seven or eight samples selected to 

represent a range of COHb levels were sent to an independent laboratory (that of Dr. F. Lee Rodkey and 

Mr. R. Robertson of the Naval Medical Research 

Institute, Bethesda, Maryland) for COHb determinations using the reference standard methodology of gas 

chromatography.1s The values obtained by gas 

chromatography were compared to those obtained by 

spectrophotometry, and the results were used to 

“fme-tune” the baseline adjustment on the spectrophotometric equipment. 

At regular intervals, four or five “blind” samples 

were sent directly from the MEC’S to both laboratories. About 200 comparisons resulted from this 

procedure, with a mean difference of 0.00 percent 

COHb and a standard deviation of 0.31 percent 

COHb. The correlation coefficient was 0.99. 

The precision or reliability of the spectrophotometric method was confirmed through dual determinations on each sample. Theoretically, the standard 

deviation of repeated COHb measurements on a single 

sample by this method should be about 0.25 

percent.g If measurements on a sample differed by 

more than 1 percent COHb (that is, by more than 

our standard deviations), the sample was rerun. The 

“stribution of differences between duplicate determinations followed a Gaussian (normal) probability 

curve, with a standard deviation of approximately 

0.25 percent. 

Finally, samples were drawn regularly from a 

group of nonsmoking laboratory personnel as a test 

of the stability of the spectrophotometric method. 

After analysis, the COHb values were compared with 

previous values from the same person. Occasional 

high values (greater than 1.2 percent) were verified 

by the gas chromatography method and were found 

to occur on days when the ambient carbon monoxide 

level was high. Thus Small’s method reliably detected 

increases in COHb of as low as 0.3 percent. 

With the strict quality control on the spectrophotometric method, it was possible to reduce the baseline uncertainty of the method to *O.1 percent 

COHb. This source of error is the only one contributing to the error of mean results obtained from 

groups of individuals; all other sources of error would 

average to zero. Thus for group comparisons, the 

method is considered to be accurate to ~0. 1 percent 

COHb. 

Limitations of data 

Although the quality control and methodological 

reification previously described justify a high degree 

of confidence in the validity and precision of the results reported here, because of a number of factors 

the reader should be cautious not to “over-interpret” 

the data, particularly when comparing an individual 

subject’s results with population distributions. Chief 

among these factors is the relative imprecision of a 

single measurement, estimated to be perhaps as much 

as 0.25 percent COHb on repeated measurements. 

For children, in particular, this variability may represent 25 or more percentile points. For the entire 

population, however, this measurement error was 

estimated to be no more than 0.10 percent COHb, so 

that cross-population comparisons should be only 

minimally affected. 

Another possible confounding factor is the interaction between the seasonal effect noted in the 

results and the itineraries of the Mobile Examination 

Centers. To minimize the effects of adverse weather 

on response rates, MEC’S traveled through the more 

northern parts of the United States in the summer 

and the more southern parts in the winter. Thus the 

effects of the severest winter weather on carbon 

monoxide levels are not represented in these data. 

Several logistical factors also must be considered 

while interpreting these data. For instance, on rare 

occasions, an MEC was situated near major traffic 

arteries. These sites may have manifested ambient 

carbon monoxide levels that were atypically high for 

the given locale, but it is not possible to quantify this 

effect with the available data. 

Another logistical factor with possible implications for the interpretation of these data was the 

shipping and handling of the samples. After collection, the samples were refrigerated until a sufficient 

number had accumulated for shipment (on ice) to 

the lab for analysis. In general, this procedure has not 

been identified as a factor that influences the resulting COHb test results. However, several shipments 

were lost; others were mishandled and arrived at the 

lab in an unanalyzable condition. Finally, some samples showed such high methemoglobin levels (greater 

than 5 percent) that the associated values for COHb 

were considered unreliable; the high metHb was 

evidence of sample deterioration. Of the 9,365 

examined subjects who should have had values for 

COHb, acceptable samples were not available for 954 

(10.2 percent). The distribution of these missing 

values did not show any race or sex bias, and the statistical weights for the remaining cases were adjusted 

to compensate for this item nonresponse as well as 

sample person nonresponse (see the section on Item 

nonresponse). 

The definition and reporting of smoking status 

(see page 6) may have had some impact on the interpretation of results in this report. The remarkably 

high COHb values for a few of the ex-smokers leads 

to the suspicion that some incorrect reporting may 

have occurred in the history. In addition, the Surpris-= 

ingly low values for some current smokers indicate 

that their smoking levels (in cigarettes per day or -

6 
� 

24
 .. 

amount inhaled) are so low that they have little or and the COHb level, particularly for current smokers. 

no effect on COHb levels. This relationship will be examined in the Series 11 

Finally, the possibility exists that there is a rela- paper in the Vital and Health Statistics series. 

tionship between the time of day of sample collection 

Recent Issues of Advance Data From Vital and Health Statistics 

No. 75. Expected Principal Source of Payment for Hospital 

Discharge: United States, 1979 (Issued: February 16, 1982) 

No. 74. Visits to Family Planning Clinics: United States, 1979 

(Issued: September 4, 1981) 

No. 73. Patient Profile, National Reporting System for Family 

Planning Services: United States, ‘1978 ‘(Issued: June 24, 

1981) 

SUGGESTED CITATION


National Center for Health Statistics, E.P. Radford


and T,A. Drizd: Blood carbon monoxide levels in


persons 3-74 years by age, United States, 1976-80.


Advanca Data from Vital and Health Statistics,


No. 76. DHHS Pub. No. (PHS) 82-1250, Public


Health Service, Hyattsville, Md. March 17, 1982.


U.S. DEPARTMENT OF HEALTH ANO HUMAN SERVICES


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Office of Health Research, Statistics, and Technology


National Center for Health Statistics


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Hyattsville, Maryland 20782


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COntaCt the NationalCenter for Health 

Statistics by dling 301-436. NCHS, 

No. 72. Visits to Family planning Service Sites: United States, 

1978 (Issued: June 29, 1981) 

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Medicare, Medicaid, and Military or Veterans Administration 

Health Benefits: United States, 1978 (Issued: 1981) 

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