Indoor Air Quality: The Contribution of Environmental Tobacco Smoke

Summary

An extensive 30-week survey of environmental tobacco smoke has been undertaken in Great Britain. The survey consisted of over 2,900 sampling operations according to a scheme which covered a range of situations to which the public are exposed during their travel and leisure as well as at home and work. Sampling took account of population distribution as well as geographical and seasonal effects.

Three components of tobacco smoke — particulate matter as measured by Minirams, carbon monoxide and nicotine — have been determined in smoking and non-smoking situations, whilst the reported presence or absence of smoking within 2h prior to sampling was used to distinguish between non-smoking and smoking environments. The survey was structured around 30 min sampling periods, using unobstrusive, portable sampling equipment capable of detecting each of the three components at less than 5% of their individual (occupational exposure limit (OEL) is the UK recognized workplace safety level).

Overall mean Miniram particulate matter was 0.56 mg m⁻³, with a smoking location mean of 0.81 mg m⁻³ and a non-smoking mean of 0.31 mg m⁻³. These results, as determined by the Miniram light scattering device are, however, known to be an overestimate when compared to methods based on the measurement of particulate mass, such as the Piezobalance. Subsequent studies in a variety of locations have shown the Miniram to over-estimate by at least a factor of 2.5 in the presence of tobacco smoke.

The overall mean carbon monoxide level was 2.4 ppm with a mean of 2.7 ppm in smoking locations and 2.1 ppm in non-smoking locations. With the limitations of the carbon monoxide monitors, this difference is not thought to be significant.

In calculating the mean results for nicotine, a value of 6.8 μg m⁻³ (i.e. half the limit of detection) was assumed whenever the nicotine level was below the limnit of detection. This has almost certainly led to an over-estimation of nicotine, particularly in nonsmoking situations, where nicotine was rarely detected. Applying this factor the mean overall nicotine concentration was 14 μg m⁻³ with a mean of 21 μg m⁻³ in smoking locations and 8 μg m⁻³ in non-smoking locations. No nicotine concentrations exceed the OEL set at 500 μ m⁻³ and 95% of all readings were below 10% of the OEL.