# Presentation: 138318

## Occupational exposure to environmental tobacco smoke in U.S. adults: Results from the 2000 National Health Interview Survey

- Zakia Coriaty Nelson, M.P.H.

## Environmental tobacco smoke (ETS)

- Also referred to as “secondhand smoke”
- A mixture of
- Sidestream smoke, or smoke emitted from a lighted cigarette, and
- Mainstream smoke, or smoke exhaled by a smoker
- ETS contains carcinogens, mutagens, and developmental toxicants

**Notes:**
Environmental tobacco smoke, also known as “secondhand smoke,” 
Is defined as the mixture of sidestream smoke, or smoke emitted from a lighted cigarette, and mainstream smoke, or smoke exhaled from a smoker, 
that pollutes air in an environment in which tobacco smoking is taking place.

ETS contains the same compounds as those inhaled by a smoker, including many carcinogens, mutagens, and developmental toxicants

## Environmental Tobacco Smoke

- Poses a significant health threat
- Cancer
- Coronary heart disease
- Asthma
- Low birth weight
- Sudden Infant Death Syndrome (SIDS)
- Other health effects

**Notes:**
Environmental tobacco smoke poses a significant health threat.  
Previous studies of ETS have linked exposure with 

Cancer of the lung, nasal sinus, breast, cervix, and bladder 
coronary heart disease morbidity and mortality, 
asthma, 
respiratory infections, 
Low infant birth weight or small for gestational age
Sudden infant death syndrome (SIDS)
and other acute and chronic health effects in adults and children.

## Environmental Tobacco Smoke

- Widespread exposure
- 30%-60% exposure in general population
- NHANES III: 87.9% of adult non-tobacco users have detectible serum cotinine
- 2000 NHIS: ETS exposure in approximately 27% of U.S. adults

**Notes:**
Exposure to environmental tobacco smoke is believed to be widespread in the population.

Studies conducted over the last 10 years have estimated that 30%-60% of the population is exposed to ETS.  

A study from NHANES in 1991 estimated that while less than 40% of U.S. non-tobacco using adults reported exposure to ETS at home or work, about 88% had detectible levels of serum cotinine, a nicotine metabolite, indicating exposure to ETS. 

Using NHIS data from 2000, it is estimated that approximately one quarter of U.S. adults reported exposure to ETS at work or at home.  

## Occupational ETS

- High density of smokers in immediate work environment
- Levels detected in work environments or workers exceed levels associated with serious health effects
- Important source of ETS exposure and a public health hazard

**Notes:**
Some environmental monitoring studies suggest that, for many groups of workers, occupational exposure to ETS may involve a high density of smokers in the immediate work environment, producing levels of ETS as high as or higher than in smoking households. 

The levels detected in workers or work environments often exceed the levels associated with serious health effects in studies of exposure to ETS in the  home

Therefore, occupational ETS may be an especially important source of exposure in certain occupation and sociodemographic subgroups as well as a substantial hazard to the public’s health

## Study Objectives

- Estimate prevalence of exposure to occupational ETS on national level
- Evaluate associations with sociodemographic and health-related factors
- Investigate differences in exposure among nonsmokers, former smokers, and current smokers

**Notes:**
The objectives of this study were to
Estimate the prevalence of occupational exposure to ETS on a national level

Evaluate which sociodemographic and health-related factors are associated with occupational ETS to identify population subgroups who may be disproportionately affected by this exposure.

Investigate the differences in occupational exposure to ETS among nonsmokers, former smokers, and current smokers.

## Data and Methods

- 2000 National Health Interview Survey and Cancer Control module
- 32,374 respondents representing over 200 million U.S. adults
- Sampling weights used to account for unequal selection probabilities and survey nonresponse

**Notes:**
The population was surveyed using the 2000 National Health Interview Survey and its supplementary Cancer Control module. 

Data were collected from approximately 32,000 respondents, representing over 200 million U.S. adults aged 18 years and over, as part of a sample of the U.S. population. 

Sampling weights were used to account for unequal selection probabilities and survey nonresponse.

## Data and Methods

- Information collected on
- Sociodemographic characteristics
- Health-related factors
- Personal smoking history
- Smoking in the home
- Workplace policies restricting smoking
- Smoking in the workplace

**Notes:**
Information was collected on: 
Sociodemographic characteristics.
Health factors.
Personal smoking history and smoking in the home.
policies restricting workplace smoking
And smoking in the Workplace, our outcome of interest

This was measured by asking individuals who worked mainly indoors whether smoking occurred in their work environment in the last week.  The 2000 cancer control module had no information about amount or duration of smoking in the work environment, so level of exposure could not be assessed or investigated.

With the large sample size of the NHIS and the enormous amount of information collected in the survey, 

## Data and Methods

- Crude estimates of percentages and standard errors
- Multivariate logistic regression to estimate odds ratios and adjusted percentages
- Analyses repeated in subgroups by personal smoking history

**Notes:**
Crude estimates of percentages of occupational exposure to ETS were calculated using SAS-callable SUDAAN, software that appropriately accounts for the complex survey design of the NHIS.

Multivariate logistic regression was used to estimate adjusted odds ratios and percentages of occupational ETS
(predicted marginals/PREDMARG give the average predicted response if all observations had been in one group– equivalent to direct standardization)

Analyses were performed for all respondents and separately by personal smoking history (that is in never, former, and current smokers).

## Data and Methods

- Large sample size provides depth for multivariate adjustment and data disaggregation/stratification
- Social and behavioral information collected allows for examination of health and policy in a social context

**Notes:**
As you will see, the large sample size of the NHIS provides a substantial amount of depth for multivariate adjustment even in the context of disaggregated or stratified data

Sociodemographic and behavioral information that is collected in addition to the health data allows for the examination of health and policy in a social context.

## Results

- 1,984 of 14,099 respondents reported smoking in work area
- 14.3% exposed to occupational ETS
- Stratified by personal smoking history
- 10.4% of never smokers
- 13.4% of former smokers
- 24.0% of current smokers

**Notes:**
Of the 14,099 respondents (unweighted) who worked “mainly indoors,” 1,984 indicated that smoking had occurred in their workplace in the last week.

Overall, 14.3% of adults who work indoors were exposed to occupational ETS. 

When stratified by personal smoking history, smoking in the workplace was experienced by 10.4% of never smokers, 13.4% of former smokers, and 24.0% of current smokers.

## Results

- Overall, associations observed with
- Age
- Sex
- Region of residence in the U.S.
- Highest level of education attained
- Occupation
- Workplace policies restricting smoking
- Smoking in the home
- Personal history of smoking
- Respondent-reported health status

**Notes:**
Overall, results from multivariate logistic regression show that occupational exposure to ETS is significantly associated with 
Age
Sex
Region of residence in the United States
Highest level of education attained
Occupation
Workplace policies restricting smoking
Smoking in the home 
Personal history of smoking
Respondent-reported health status

## Logistic Regression Results: Overall

**Notes:**
Here are the same results in tabular format, and I’ve broken up the table into the following three slides:
There is a significant decreasing linear trend with increasing age

And a significant negative association with being female and with living in the west region of the U.S. (which may reflect CA’s anti-smoking legislation)

## Logistic Regression Results: Overall

**Notes:**
I think some of the most interesting results are on this slide:
There is a significant negative trend in the association with occupational ETS as education increases– this trend has significant linear and quadratic components.

A significant positive association was observed with working in a blue collar or service industry job

The most dramatic association, however, was observed with the absence of a workplace policy restricting smoking, which had an odds ratio of over 7.

## Logistic Regression Results: Overall

**Notes:**
Here are the associations with smoking in the home (dichotomized to represent rarely/never smoking in the home versus smoking in the home for 1-7 days/week)

With personal smoking history– the association with formerly or currently smoking could be due to smokers choosing jobs where they are allowed to smoke at work.
The association with self-reported health status is very likely to be one in which being exposed to smoking in the workplace may lead an individual to report they have poorer health

## Results

- Overall, no association with
- Race/ethnicity
- Place of residence
- Marital status
- Family income
- Citizenship status
- Health insurance coverage status

**Notes:**
Overall, no associations were observed with:
race/ethnicity, 
place of residence (central city, noncentral city, other), 
marital status, 
family income, 
citizenship status, 
or health insurance coverage status. 

## Results: Subgroup Analyses

- Stratified by personal smoking history, significant decreasing trend in association as education increased
- Positive associations were observed with
- Being male
- Working in a service industry, blue collar, or agriculture/fishing job
- A lack of workplace policies restricting smoking

**Notes:**
I was surprised to see that odds ratios produced in the three subgroup analyses were similar and largely consistent with the overall analysis.  

In all three subgroups (i.e., never, former, and current smokers), significant decreasing trends in occupational exposure to ETS were observed as education increased. 

Positive associations were observed with:
Being male.
Working in a service industry, blue collar, or agriculture/fishing job.
A lack of workplace policies restricting smoking.

## Figure 1.  Odds ratios of exposure to occupational environmental                   tobacco smoke in "mainly indoors" workers in relation to                   highest level of education, by personal smoking history

**Notes:**
Here we see some of the results from the subgroup analyses in graphical format.  
As you can see, as education increases on the x-axis, the odds ratio of occupational exposure to ETS declines in a linear and sometimes quadratic way.
This association was strongest in former and current smokers.

## Figure 2.  Percentage of "mainly indoors" workers at whose 	   workplace smoking occurred during the last week, by                  personal smoking history and sex

**Notes:**
Here we see the percentages of men versus women who experienced occupational ETS, stratified by personal smoking history.

While the relationship is similar in each of the subgroups, the prevalence is much higher in current smokers than in never or former smokers.

## Figure 3.  Percentage of "mainly indoors" workers at whose                  workplace smoking occurred during the last week, by                  personal smoking history and occupation

**Notes:**
This graph shows the percentages of occupational exposure to ETS in each of the three occupation categories, also stratified by personal smoking history.

Again, we see a similar association in each of the subgroups, with the current smokers experiencing the highest prevalence of exposure to occupational ETS.

## Figure 4.  Odds ratios of exposure to occupational environmental                   tobacco smoke in "mainly indoors" workers in relation to                   workplace smoking policies, by personal smoking history

**Notes:**
Lastly, this graph shows the odds ratios of exposure to occupational ETS associated with workplace policies restricting smoking.

In non-smokers, individuals who had no workplace policies restricting smoking had an odds of exposure over 5 times that of those subject to workplace smoking policies.

Even more dramatic are the results for the current smokers, who have an odds ratio of exposure to occupational ETS over 12 if their workplace lacked a smoking policy.

## Conclusions

- Workplace smoking policies likely are efficacious in reducing occupational exposure to ETS
- Others disproportionately affected:
- Men
- Less educated
- Service industry and blue collar workers
- Those exposed to ETS at home

**Notes:**
The presence of a workplace policy restricting smoking was the factor most strongly associated with occupational exposure to ETS, suggesting workplace smoking policies are efficacious in reducing this exposure. 

Other groups that are disproportionately affected by exposure to occupational ETS are male, 
less educated, 
and employed in occupations that are not white collar 
as well as those that are exposed to additional ETS in the home.

## Conclusions

- Current smokers
- Have high odds of exposure to occupational ETS
- May have concurrent high prevalence of additional exposure to ETS at home
- May be at even greater risk of serious health conditions

**Notes:**
Current smokers have particularly high prevalence of exposure to occupational ETS and also may have high prevalence of additional exposure to ETS at home. 

Some studies suggest that ETS may be just as harmful to smokers as it is to nonsmokers; therefore, current smokers who are additionally exposed to ETS in their workplace or home may be at an even greater risk of serious health conditions. 

## Conclusions

- Bans on workplace smoking
- Reduce exposure of nonsmokers to ETS
- Decrease the number of cigarettes consumed daily by current smokers
- Increase cessation attempts and successes in current smokers
- Workers reporting occupational exposure to ETS dropped from 54% in 1992 to 7% in 1999.

**Notes:**
Several studies suggest that bans on workplace smoking 
not only dramatically reduce the exposure of nonsmokers to environmental tobacco smoke, 
but they also decrease the number of cigarettes that smokers consume daily 
and increase cessation attempts and successes. 

In California, the proportion of workers reporting occupational exposure to ETS dropped from 53.7% in 1992 to 6.6% in 1999 after the State prohibited all workplace smoking, providing dramatic evidence of the efficacy of such restrictions. 

## Conclusions

-    National-level estimates demonstrate that occupational exposure to ETS continues to pose a threat to the health of the U.S. working adult population

**Notes:**
Despite that exposure has been reduced by similar types of regulatory policies and legislation,
these national-level estimates demonstrate that occupational environmental tobacco smoke continues to pose a threat to the health of the U.S. working adult population. 

## Next Steps

- Evaluation of interaction between factors associated with occupational ETS
- Publication of study results in journal

**Notes:**
The next steps for me include the evaluation of interaction between factors associated with occupational ETS 

And publication of the results of this study in a journal.