Miljøprojekt, 1003 – The indoor and outdoor concentrations of particulate air-pollution and PAHs in different size fractions and assessment of exposure and health impacts in the Copenhagen population

The indoor and outdoor concentrations of particulate air-pollution and PAHs in different size fractions and assessment of exposure and health impacts in the Copenhagen population

Summary and conclusions

Fifteen one-week samples of PM₁, PM_2.5, inhalable dust (PM_inh) and 16 polycyclic aromatic hydrocarbons (PAHs) were collected inside and outside of an uninhabited 4^th floor apartment at the Jagtvej street canyon in central Copenhagen during winter, spring and summer in 2002. Similar urban background samples were collected at a 2 km distant 4^th floor high rooftop. PAHs in PM₁ and PM_inh were collected on glass fibre filters only. PAHs in PM_2.5 were collected on glass fibre filters followed by adsorbent sample and backup tubes containing Tenax. PM was determined by filter weighing. The PAHs were analyzed by liquid extraction of filters and adsorbent tubes followed by high performance liquid chromatography with UV and fluorescence detection.

The Copenhagen particulate air-pollution was dominated by fine particles. App. 70 wt% of the PM_2.5 consisted of PM₁ at all sites. The average PM_2.5 content in PM_inh was 54 and 69 wt% at Jagtvej and in the urban background, respectively. Indoors PM_inh consisted almost entirely of PM_2.5. Correlation analysis showed a strong relationship between PM₁, PM_2.5 and PM_inh at Jagtvej and in the urban background. However, PM at Jagtvej exceeded the urban background concentrations. The difference suggests that traffic on average contributed with 3.5±1.9 g/m³, 5.0±2.7 g/m³ and 14.6±4.0 g/m³ to PM₁, PM_2.5 and PM_inh, respectively.

Indoor PM correlated well with PM in both the street and the urban background. However, indoor-outdoor ratios below unity (0.77±0.21 for PM₁ and 0.77±0.24 for PM_2.5) were only achieved using PM-concentrations measured in the street at Jagtvej. The average indoor PM_2.5 concentration (15.20 μg/m³) exceeded the annual indoor PM_2.5 concentration of 15 μg/m³, which is recommended in the US based on the US-EPA air-quality guideline for PM_2.5. At the best, the outdoor PM_2.5 concentrations (19.80 μg/m³ at Jagtvej and 14.85 μg/m³ in the urban background) just complied with the target values proposed by the EU CAFE Working Group to be within 12 to 20 μg/m³. Assessment of adverse health effects induced by PM_2.5 at 95% CI suggested 780520 excess accumulated deaths per million in Copenhagen in 2002. Additionally, 1556701 excess hospitalisations were predicted per million inhabitants for respiratory symptoms and all cardiovascular disease, combined.

In PM_2.5 samples the total concentrations of the 16 US-EPA gas and particle phase priority PAHs (ΣPAH) were 15-284 ng/m³ indoors, 46-235 ng/m³ outdoors, and 2-105 ng/m³ in the urban background. The concentrations were probably underestimated due to extraction recovery below 100%, breakthrough, and reaction with ozone and nitrogen oxides during sampling. The real concentrations may be up to two times higher than observed. Urban background, traffic and indoor sources contributed to the overall concentration of PAHs in the uninhabited apartment. Traffic in the Jagtvej street canyon and indoor sources appeared to be the most important sources for PAHs indoors. The WHO unit risk value of 8.7 10^-5 per ng/m³ B(a)P for life-time cancer risk suggests that ~10 cancer cases per 106 inhabitants may occur at a life-time exposure to the PAH-concentrations observed in the apartment. For comparison, 8 and 5 cases per 10⁶ inhabitants are expected from the street and urban background concentrations, respectively. B(a)P may be an inadequate marker for assessment of cancer induced by urban air-pollution. Differences between indoor and outdoor PAH profiles and presence of other carcinogenic compounds may result in serious estimation errors.