Survei pemantauan Kualitas Udara pada tahun 2011 di 78 tempat umum di Kota Semarang menunjukkan rata-rata PM2.5 di tempat-tempat yang diperbolehkan merokok adalah 94,76 mg/m3 dan di tempat-tempat yang tidak diperbolehkan merokok adalah 34,60 mg/m3. Café dan restoran adalah tempat umum dngan tingkat PM2.5 tertinggi. Rata-rata dari PM2.5 di restoran adalah 72,60mg/m3 dan di café 64,84mg/m3. Penelitian ini bertujuan untuk mengetahui efek paparan asap rokok terhadap fungsi paru dan cotinine urin karyawan cefe dan restoran di kota Semarang. Data dikumpulkan dari 13 cafe dan restoran dengan responden 70 orang karyawan non-perokok. Instrumen yang dipakai adalah spirometri, enzyme-linked immunosorbent assay (Elisa), aerosol sidepack, dan kuesioner. Hasil penelitian menunjukkan bahwa 20% responden mengalami restriksi ringan, 2,9% obstruksi ringan dan 2,9% obstruksi sedang. Rata-rata cotinine urine karyawan café adalah 42,902ng/ml dan karyawan restoran 33,609ng/ml. Rata-rata PM2.5 di café adalah 121,65 mg/m3 dan di restoran adalah 68,27μg/m3. Faktor-faktor yang berhubungan dengan cotinine urine adalah lama paparan SHS per hari (rho = 0,364, p-value = 0,002) dan perilaku merokok rekan kerja (p-value = 0,006). Umur berkorelasi dengan fungsi paru (rho = 0,272, p-value = 0,023) dan ada hubungan negative antara cotinine urin dan fungsi paru (rho = 0,266, p-value = 0.026).Air Quality Monitoring Survey in 2011 at 78 public places in Semarang city showed the average of PM2.5 in places where smoking allowed was 94.76mg/m3 and in places where smoking not allowed smoking was 34.60mg/m3. Café and restaurant was the public places with the highest PM2.5 levels. The average of PM2.5 in restaurant was 72.60mg/m3 and 164.84mg/m3 in café. This research aims to determine effects of secondhand smoke exposure on lung function and urine cotinine levels of café and restaurant employee in the Semarang city. Data was collected from 13 cafes and restaurants and the respondents are 70 non-smokers employees. The instruments were spirometry, enzyme-linked immunosorbent assay (Elisa), sidepack aerosols, and questionnaire. The result showed that 20% of respondents had mild restriction, 2.9% mild obstruction and 2.9% moderate obstruction. The average level of urine cotinine of cafe employees was 42.902ng/ml and 33.609ng/ml in restaurants employees. The average of PM2.5 levels in the Cafe was 121.65 μg/m3 and in Restaurant was 68.27μg/m3. Factors related to urine cotinine were duration of SHS exposure per day (rho=0.364, p-value=0.002) and colleague smoking behavior (p-value=0.006). Age was correlated with lung function (rho=-0.272, p-value=0.023) and there was negative correla-tion between urine cotinine and lung function (rho=-0.266, p-value=0.026).