Table 1.

Characteristics and evaluation of quality of 14 studies on ambient exposure to traffic-related air pollution

Study ID (Reporting quality)	Location and study design	Age (years)	Total participants	Lung cancer cases	Exposure† (μg/m3)	Exposure assessment	Outcome	Outcome assessment	Covariates adjusted for
Yorifuji et al. 201314 (A)	Shizuoka, Japan, Cohort	65–84	14001	116	NO2: 35.11	LUR modeling	Lung cancer and hemorrhagic stroke	Obtained from the database of the Ministry of Health,Labor and Welfare of Japan	Age, sex, smoking, BMI, hypertension, diabetes, financial capability and area mean taxable income
Raaschou-Nielsen et al. 201315 (A)††	European, 17 cohorts	42.8–73.1 (mean age)	2380–108018	18–678	PM10: 13.5–48.1, PMcoarse:4.0– 20.8PM2.5: 6.6–31.0, PM2·5absorbance: 0.5-3.2 NO2: 5.2–59.8 NOX: 8.7–107.3	LUR model	Lung cancer	Histology	Age, sex, calendar time, smoking related variables, occupation, fruit intake, marital status, educational level, employment status and area-level socioeconomic status
Jerrett et al. 201316 (B)	California, U.S. Cohort	≥30	73711	1481	PM2.5: 14.09 NO2: 12.27‡ O3: 50.35‡	Monthly average monitoring data and LUR models	All cause of death including lung cancer	Ascertained by volunteers and using the National Death Index	Lifestyle, dietary, demographic, occupational and educational factors
Hystad et al. 201317 (A)	8 provinces, Canada, Case-control	63.5 and 59.0(mean age for cases and controls)	5897	2390	PM2.5: 11.9 NO2: 15.4‡ O3: 20.3	Fixed site monitoring data and proximity measures	Lung cancer	Histology	Age, sex, educational attainment, smoking related variables, alcohol and meat consumption, occupational exposure and geographic covariates.
Cesaroni et al. 201318 (B)	Roma, Italy, Cohort	≥30	1265058	12208	NO2: 44 PM2.5: 23	LUR modeling and PM2.5 dispersion model	All cause of death including lung cancer	Obtained from Lazio regional health information system	Sex, marital status, place of birth, education, occupation, and area-based socioeconomic position
Cao et al. 201019 (B)	17 provinces, China, Cohort	55.8 (mean age)	70947	624	TSP: 289 SO2: 73 NOX: 50	Fixed-site monitoring data	All cause of death including lung cancer	Hospital records and death certificates	Age, sex, BMI, physical activity, education, smoking status, age at starting to smoke, cigarettes per day, alcohol intake, and hypertension
Beelen et al. 200820 (A)	Netherlands, Case-Cohort	55–69	120852	2183	BS: 11.6, NO2: 36.9 SO2: 13.7 PM2.5: 28.2	Regulatory monitoring data and LUR models	Lung cancer	Histopathology and cytopathology	Full cohort: age, sex, smoking status and area level indicators of socioeconomics
Vineis et al. 200621 (A)	9 countries, Europe, Nested case-control	60.4 and 60.0 (mean ages for cases and controls)	1008	271	NO2: 12.0–64.7§ PM10: 19.9–73.4§ SO2: 1.1–30.6§	Home addresses and data from monitoring stations	Lung cancer	Histological conformation	Age, sex, country, smoking status, time since recruitment, education, BMI, physical activity, cotinine, occupational index and intake of fruit, vegetables, meat, and alcohol )
Laden et al. 200622 (B)	6 cities, U.S. Cohort	25–74	8096	226	PM2.5: nearly 10–40§	Fixed air-monitoring station	All cause of death including lung cancer	Data obtained from National Death Index	Current or former smoking, number of pack-years of smoking for former and current smokers separately, education, and body mass index
Jerrett et al. 200523 (A)††	Los Angeles, U.S. Cohort	NA	22905	434	PM2.5: 9.0–27.1§	Data from state and local district monitoring stations	All cause of death including lung cancer	NA	Age, sex, age, O3(average of 4 highest 8 h maxima) and 44 other covariates including lifestyle, dietary, demographic, occupational and educational factors
Filleul et al. 200524 (A)	7 towns, France, Cohort	25–29	14284	178	SO2: 17–85 TSP: NA BS: 18–152 NO2: 12–61 NO: NA	Data from centrally located pollution monitoring station	All cause of death including lung cancer	Data from specialized department of the National Institute of Health and Medical Research (INSERM)	Age, smoking habits, body mass index, educational level, occupational exposure, and stratified by sex
Nafstad et al. 200325 (A)	Oslo, Norway, Cohort	40–49	16209	422	NOX: 10.7¶ SO2: 9.4¶	Model calculations using data for observed concentrations and emission from point sources	Lung cancer	Obtained from Norwegian cancer register	Age, smoking habits, physical activity, occupation, height and weight
Pope et al. 200226 (A)	50 states. U.S. Cohort	≥30	Approximately 500000	NA	PM2.5: 17.7	Inhalable particle monitoring network and National Aerometric Database	All cause of death including lung cancer	Death certificates	Age, sex, race, smoking, education, marital status, body mass, alcohol consumption, occupational exposure and the diet
Nyberg et al. 200027 (A)	Stockholm, Sweden, Case-control	40–75	3406	1042	NO2: 19.85¶ SO2: 52.75¶	Source-specific emission data and dispersion modeling	Lung cancer	Histology and cytology	Age, selection year, smoking, radon, socioeconomic grouping, occupational exposure to diesel exhaust, other combustion products and asbestos, and employment in risk occupation.

†Mean concentration of exposure. ‡Exposure concentration is measured by ppb. §Range of exposure concentration. ¶Median concentration of exposure. ††Studies evaluated with modified STROBE items. BS, black smoke; LUR, land-use regression; TSP, total suspended particles.