Ambient and exhaled carbon monoxide levels in a high traffic density area in Christchurch.

AIMS

To monitor outdoor and indoor levels of carbon monoxide (CO) in a sample of shops and offices in a high traffic density area of Christchurch and to measure end-exhaled CO levels in the respective shop and office workers in order to assess the potential for adverse health effects.

METHODS

Outdoor CO was monitored at two fixed locations near a congested traffic intersection in Riccarton Road, Christchurch. Six shops and three offices were purposefully selected within 300 metres of the monitoring sites. Indoor CO was monitored with a portable ambient gas monitor. Participants in each shop and office underwent end-exhaled breath testing for CO three times daily at approximately 0900, 1300 and 1600 hours for the week their premises was monitored.

RESULTS

Outdoor CO levels exceeded the ambient 8-hour guideline of 8 ppm on five of the 37 (14%) monitored days and indoor CO levels exceeded the ambient 8-hour guideline on two days. Thirty-two workers, mean age (SD) 34 (9.9) years, participated in the study. End-exhaled CO levels were all below 7 ppm, within the normal range for non-smokers. There was no consistent relationship between indoor CO levels and outdoor CO levels.

CONCLUSIONS

The 8-hour ambient guideline for CO was exceeded on several days but there was no evidence of elevated exhaled CO levels in any of the participants. It is unlikely that such exposures would impact adversely on the health of workers unless they suffered from an underlying cardiovascular disorder.