Kim et al. [30]	2004	Cross- sectional study	US (San Francisco)	Children	Traffic intensity (90,000 - 210,000 veh/day) Distance (<300 m downwind) Pollutants measured PM₁₀ PM_2.5 BC NO_x NO₂ NO	RD Asthma Bronchitis	Observation of difference concentrations between schools nearby versus more distant (or upwind) from major roads Association between respiratory symptoms and traffic related pollutants Findings support the hypothesis that TRAP is associated with respiratory symptoms
Lindgren et al. [31]	2009	Cross- sectional study	Southern Sweden	Adults (18 - 77 years)	Traffic intensity (0 - 1 cars/min; 2 - 5 cars/min; 6 - 10 cars/min and >10 cars/min based upon 24-hour mean levels) Pollutants measured NO_x modeled exposure)	RS Asthma symptoms Chronic bronchitis symptoms RD Asthma COPD CBE	Living close to traffic (within 100 m of a road with >10 cars/minute) was associated with prevalence of asthma diagnosis and COPD diagnosis, and symptoms of asthma and bronchitis. Annual average NO_x was associated with COPD diagnosis and symptoms of asthma and chronic bronchitis
Hoek et al. [32]	2002	Cohort study	Netherlands	Adults (55 - 69 years)	Distance Pollutants measured BC NO₂	RD Lung cancer Cardio- pulmonary diseases	Cardiopulmonary mortality was associated with living near a major road. Long-term exposure to traffic-related air pollution may shorten life expectancy
Migliore et al. [33]	2009	Cross- sectional study	Italy	Children (6 - 7 years) and adolescents (13 - 14 years)	Traffic intensity	RS Asthma symptoms Cough or phlegm	Traffic density was weakly associated with asthma symptoms but there was a stronger association with cough or phlegm. Children living in zones with intense traffic are at higher risk for respiratory effects.