Table 2.
Characteristics of 50 studies included in the meta-analysis.
| First author | Year | Location | Air pollutant | Study design | Sample size | Study group | Outcome |
|---|---|---|---|---|---|---|---|
| De Marco (37) | 2002 | Italy | NO2 | Cross-sectional survey | 18,873 | Adults | Asthma attack, chest tightness, wheezing |
| Sunyer (38) | 2002 | Spain | NO2 | Case-crossover design | 1,078 | All | Mortality due to asthma |
| Gent (39) | 2003 | USA | O3 | Prospective study | 271 | Children | Chest tightness(1 h), Shortness of breath (1 h), Chest tightness(8-h), Shortness of breath (8 h) |
| Mar (2) | 2004 | USA | PM2.5, PM10 | Unknown | 25 | children, adults | Trouble breathing, coughing, sputum production, wheezing |
| Migliaretti (40) | 2004 | Italy | NO2 | Case–control study | 1,060 | Children | Asthma hospitalizations |
| Analitis (41) | 2006 | Europe | PM10 | Unknown | Unknown | All | Respiratory mortality |
| Brauer (5) | 2007 | Netherlands | PM2.5 | PIAMA prospective birth cohort study | ~ 4,000 | Children | Wheezing, doctor-diagnosed asthma, ear/nose/throat infections, flu |
| Smargiassi (42) | 2009 | Canada | SO2 | Time-stratified case-crossover | 3,469 | Children | Asthma emergency department visits, asthma hospitalization |
| Kan (43) | 2010 | Thailand, China | SO2 | Short-term association study | Unknown | Adults | Respiratory mortality |
| Silverman (44) | 2010 | USA | O3 | Unknown | 75,383 | Adults | Asthma HA |
| Weinmayr (3) | 2010 | Germany/Italy | PM10, NO2 | Meta-analysis | 36 | Children | Asthma symptoms, coughing, asthma symptoms |
| Katanoda (45) | 2011 | Japan | PM2.5, NO2, SO2 | Prospective cohort study | 63,520 | All | Mortality due to lung cancer and respiratory diseases |
| Takenoue (6) | 2012 | Japan | NO2 | Meta-analysis | 12 | Children | Asthma development, wheezing |
| Belanger (4) | 2013 | USA | NO2 | Prospective, year-long study | 1,342 | Children | Asthma severity, wheezing, night symptoms due to asthma, medication use due to asthma |
| Kloog (12) | 2013 | USA | PM2.5 | Short-term exposure | 46,8,570 | All | PM-related mortality |
| Raaschou-Nielsen (46) | 2013 | Europe | PM2.5, PM10 | Cohort study | 312,944 | All | Lung cancer, adenocarcinoma |
| Cortez-Lugo (1) | 2015 | Mexico | PM2.5 | Questionnaire | 29 | Adults | COPD cough, COPD phlegm |
| Fan (8) | 2016 | China | PM2.5 | Meta-analysis | 16 | Children, adults, all | Asthma ED |
| Ghozikali (47) | 2016 | Iran | NO2, O3, SO2 | Unknown | Unknown | All | COPD hospitalizations, COPD hospitalization, COPD HA |
| Greenberg (48) | 2016 | Israel | SO2 | Exposure assessment | 137,040 | Children | Asthma severity |
| Hasunuma (49) | 2016 | Japan | NO2 | Nested case–control study | 853 (case),3,409 (control) | Children | Persistence of asthmatic symptoms |
| Mirabelli (50) | 2016 | USA | PM2.5 | Call-back survey | 50,356 | Adults | Any asthma symptoms |
| Pollitt (51) | 2016 | Canada | Aluminum, iron, magnesium, sulfur, nickel, vanadium, Chromium, arsenic, manganese, barium, copper, antimony, zinc | Questionnaire | 217 | Children | Airway inflammation due to asthma |
| Li (15) | 2016a | China | NO2, SO2 | Meta-analysis | 59 | All | COPD exacerbations |
| Li (52) | 2016b | China | SO2 | Unknown | 10,095 | Adults | COPD mortality |
| Day (53) | 2017 | China | O3 | Longitudinal study | 89 | Adults | Pulmonary inflammation |
| Khaniabadi (54) | 2017 | Iran | O3 | Unknown | Unknown | All | Cardiopulmonary mortality, COPD hospitalization |
| Lamichhane (32) | 2018 | India | PM2.5, PM10, NO2 | Unknown | 1,264 | Adults | Reduced lung function due to COPD |
| Magzamen (55) | 2018 | USA | PM10, NO2 | Unknown | 35 | Adults | Inhaler use due to COPD |
| Mao (34) | 2018 | China | Copper, iron | Case–control study | 33 | All | Asthma susceptibility |
| Hansel (56) | 2019 | USA | PM2.5 | Longitudinal study | 484 | Children | Uncontrolled asthma |
| Huang (57) | 2019 | Taiwan | PM2.5 | Exposure assessment | 3,941 | Adults | Susceptibility to COPD |
| Wu (7) | 2019 | USA | Lead | Cross-sectional, population-based study | 5,866 | Children | Risk for active asthma, wheezing |
| Mercan (58) | 2020 | Turkey | SO2 | Unknown | 710 | Adults | Asthma hospitalization, COPD hospitalization |
| Pepper (59) | 2020 | USA | O3 | Randomized controlled trial | 287 | Children, adults | Asthma rescue inhaler use |
| Yu (14) | 2020 | Australia | PM2.5 | Meta-analysis | 242,320 | all | Respiratory mortality |
| Shin (60) | 2021 | Canada | PM2.5, PM10, NO2 | Population-based study | 558,738 | Adults | COPD |
| Yan (61) | 2022 | China | PM2.5 | Retrospective | 39,054 | All | Chronic bronchitis, asthma, COPD, chronic respiratory disease |
| Mebrahtu (62) | 2023 | UK | PM2.5, PM10, NO2 | Retrospective | 124,808 | All | Respiratory illnesses |
| Aron (63) | 2023 | USA | PM2.5 | Time stratified case-crossover | 19,243 | Adults | COPD |
| Kangas (64) | 2023 | Belgium | PM2.5 | Census | 437,340 | Adults | Asthma |
| Marchetti (65) | 2023 | Italy | PM2.5, PM10, NO2 | Multi case–control | 16,173 | Adults | Rhinitis, COPD |
| Wang (66) | 2023 | Taiwan | Arsenic | Cross-sectional | 1,563 | Adults | Lung fibrotic, bronchiectasis |
| Yang (67) | 2024 | China | O3 | Retrospective | 4,574 | all | COPD |
| Stowell (68) | 2024 | USA | O3 | One state case-crossover | 111,71,779 | Children | Allergy, asthma, respiratory disorders, respiratory infections |
| Yu (69) | 2024 | China | Cu, Zn, Se | Survey | 2,807 | Adults | COPD, emphysema, tracheitis |
| Kwon (70) | 2024 | South Korea | NO2 | Survey | 22,387 | Adults | COPD |
| Zhang (71) | 2024 | China | O3 | Prospective cohort | 10,973 | Adults | Asthma |
| Zheng (72) | 2024 | China | PM2.5, PM10 | Multistage probability based | 7,371 | All | Asthma, wheezing, dyspnea |
| Xing (73) | 2024 | China | O3 | Population-based study | 6,537 | all | COPD |
COPD, chronic obstructive pulmonary disease; ED, emergency department; HA, hospital admission; PM, particulate matter; PIAMA, prevention and incidence of asthma and mite allergy.