Author
Studies / participants
Exposure/intervention (n studies)
Comparator/assessments
Outcomes
Kun Han et al., 2021 [32]
27 studies: 19 cohort, 7 cross-sectional, and 1 case-control. 16 conducted in Europe, 2 in North America, 9 in Asian countries
PM2.5 (15); NO2 (22); Benzene (4) and TVOCs (2)
ISSAC or ATS questionnaires to understand respiratory symptoms and asthma
TRAP increased the risk of asthma among children: PM2.5 (meta-OR = 1.07, 95% CI:1.00; 1.13), NO2 (meta-OR = 1.11, 95% CI:1.06; 1.17), Benzene (meta-OR: 1.21,95% CI:1.13; 1.29), TVOCs (meta-OR:1.06, 95% CI: 1.03; 1.10)
Bettiol et al., 2021 [35]
26 studies: based on 21 pregnancy or birth cohorts, and 2 case-control. 10 conducted in Europe, 8 in North America, 2 in Asian countries and 1 in Mexico PM10, PM2.5, PM coarse, and NO during pregnancy and the first 2 years of the child’s life
Follow-up periods varied according to the outcome, ranging from 6 to 48 months for wheezing and from 2 to 10 years for asthma, though in the majority of studies on asthma incidence children were followed up at least up to school age.
The second trimester of pregnancy seemed to be particularly critical for asthma risk. As for exposure during early life (15 cohorts), most studies found a positive association between PM (7/10 studies) and NOx (11/13 studies) and the risk of asthma development, while the risk of wheezing development was controversial.
Khreis et al., 2017 [36] 41 studies: 31 cohort, 6 case-control, and 4 cross-sectional BC, CO, NOx, NO, NO2, PM2.5, PM10, PM coarse, UFPs risk of asthma reported as incidence or lifetime prevalence from birth until 18 years old Positive and statistically significant associations between asthma onset and the exposure to BC, NO2, PM2.5 and PM10, with the least heterogeneity detected in the BC and PM analyses and the most detected in the NO2 and NOx analyses.
Lau et al., 2018 [37]
7 studies: all cohort studies Canada, France, USA, Sweden, Netherlands, and Norway
CO, NO2, NOx, PM2.5, and PM10
childhood asthma and wheezing phenotypes
TRAP is associated with the development of childhood transient and persistent asthma/wheezing phenotypes but may not be associated with late-onset asthma/wheezing. Associations were inconsistent and interpretation of the results should be drawn cautiously
G. Bowatte et al., 2015 [34]
19 studies: 11 birth cohorts 7 in Europe and 4 in North America
BC, NO2, NOx, PM2.5, and PM10
asthma, wheeze, eczema, hay fever and sensitization to allergens
TRAP increased the risk of asthma in childhood: PM2.5: OR 1.14, 95%CI 1.00; 1.30 per 2mcg/m3 BC: OR 1.20, 95%CI 1.05; 1.38 per 1*10-5 m-1 Early childhood exposure to TRAP is associated with the development of asthma up to 12 years of age. Increasing exposure to PM2.5 is associated with allergic sensitization
Favarato et al., 2014 [38] 18 studies NO2 at home (12) and/or school (8) asthma symptoms/ diagnosis by questionnaire NO2: OR: 1.06 (95 % CI: 1.00; 1.11)
H. R. Anderson et al., 2013 [39]
16 birth cohorts Based in Europe (11) or North America (5). BC, NO2, NOx, O3, PM2.5, and PM10 O3, SO2
incidence of asthma (11), the incidence of wheeze (5), lifetime prevalence of asthma (4) and lifetime prevalence of wheeze (3)
NO2: OR 1.07 (95% CI: 1.02; 1.13) per 10 μg/m3. PM2.5: OR 1.16 (95% CI: 0.98; 1.37) per 10 μg/m3. estimates were reduced in size and statistical significance by adjustment for publication bias but remained positive
Gasana et al., 2012 [40]
19 included: 10 cross-sectional. and 9 cohort studies, 9 conducted in Europe, 5 in North America, 4 in Asia, 1 in Latin America
CO, NO, NO2, SO3, O3, PM2.5, and PM10
ISSAC questionnaires to understand respiratory symptoms and asthma and/or physician diagnosis of asthma and wheeze
TRAP increased the risk of asthma in childhood: NO2 (meta-OR: 1.05, 95% CI: 1.00; 1.11), NO (meta-OR: 1.02, 95% CI: 1.00; 1.04), CO (meta-OR: 1.06, 95% CI: 1.01; 1.12) and of a higher prevalence of wheeze in children: SO2 (meta-OR: 1.04, 95% CI: 1.01; 1.07) PM (meta-OR: 1.05, 95% CI: 1.04; 1.07)