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

5 Conclusions

PM in Copenhagen and in the urban background was dominated by fine particles. Approximately 70 wt% of PM_2.5 consisted of PM₁. The average content of PM_2.5 in PM_inh was 54 and 69 wt% at Jagtvej and in the urban background, respectively, whereas PM_inh in the uninhabited apartment consisted almost entirely of PM_2.5.

There was a strong correlation (p = 0.000) between PM₁, PM_2.5 and PM_inh in the street and city background. However, the difference between PM concentrations at Jagtvej and in the urban background suggested that traffic contributed with 3.5±1.9 μg/m³, 5.0±2.7 μg/m³ and 14.6±4.0 μg/m³ to PM₁, PM_2.5 and PM_inh, respectively.

The indoor PM correlated well with the outdoor PM concentrations at both Jagtvej and in the urban background (p < 0.004). However, the most reasonable I/O ratios were achieved using the PM-concentrations measured in the street at Jagtvej.

The average indoor (15.20±5.04 μg/m³) and outdoor Jagtvej PM_2.5 concentrations (19.80±7.66 μg/m³), exceeded the ASHRAE and US-EPA annual average air-quality guideline of 15 μg/m³, respectively. The average PM_2.5 concentration in the urban background (14.85±5.99 μg/m³) was at the limit of the US-EPA guideline. However, at the best, the outdoor concentrations just complied with the target values proposed by the EU CAFE Working Group to be within 12 to 20 μg/m³.

Assessment of the adverse health effects induced by PM_2.5 suggests 780±520 excess deaths occurred per million inhabitants in Copenhagen in 2002. Additionally, 1006±701 and approximately 550 excess hospitalisations were predicted for cardiovascular disease and respiratory symptoms, respectively.

In the PM_2.5 samples the total concentrations of the 16 US-EPA priority PAHs (ΣPAH) in the gas plus particle phases were 15-284 ng/m³ indoors, 46-235 ng/m³ outdoors, and 2-105 ng/m³ in the urban background. The concentrations were underestimated due to extraction recovery below 100%, breakthrough, and reaction with ozone and nitrogenoxides during sampling. The real concentrations may be a factor of two times higher than the observed concentrations.

Urban background, traffic at Jagtvej and indoor sources contributed to the PAH-concentrations in the uninhabited apartment. Traffic in the Jagtvej street canyon and indoor sources appeared to be the most important sources for PAHs indoors.

The average B(a)P concentration exceeded the 0.0125 ng/m³ limit for 10^-6 life-time cancer risk established by WHO at all sites. Based on the B(a)P unit risk value (8.7 10^-5 per ng/m³) app. 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 may be expected from the street and urban background concentrations, respectively.

B(a)P may be inadequate for assessment of cancer risk from atmospheric air-pollution. Differences between e.g., indoor and outdoor PAH profiles and presence of other important carcinogenic compounds may result in serious estimation errors. Future studies of cancer risks from air-pollution should include analysis of other carcinogenic compounds as well.