Table 1 Summary of studies investigating the prevalence of asthma assessing respiratory clinical manifestations and previous clinical diagnoses of asthma

Gourgoulianis et al. (2001) [31]

874

Greece, three groups living between 0 and 500 m, 501 and 800 m and between 801 and 1,200 m above sea level

Questionnaires evaluating asthma prevalence, asthma-related morbidity in terms of days of school lost and nocturnal dyspnea

Soto-Quiros et al. (2002) [27]

9,931

Costa Rica, coastal regions (below 1,000 m) and highland regions (above 1,000 m)

Questionnaires evaluating asthma prevalence and clinical manifestations

Kawada et al. (2004) [35]

17,402

Japan, three subgroups living between 0-100 m, 100–200 m and 200-1,200 m

Questionnaire to evaluate asthma prevalence

Weiland et al. (2004) [25]

Unspecified number of children between 6 and 7 years old, 463,801 subjects between 13 and 14 years old

Worldwide, in a variety of environments at different altitudes

Questionnaire evaluating the prevalence of asthma clinical manifestations

Yangzong et al. (2006) [29]

2,026

Tibet, 4,300-4,400 m

Questionnaire to evaluate asthma prevalence and clinical manifestations

Droma et al. (2007) [30]

3,190

Tibet, 3,659 m

Questionnaire to evaluate asthma prevalence and clinical manifestations

Kurt et al. (2007) [32]

25,843

Turkey, 14 cities at different altitudes

Questionnaire evaluating asthma clinical manifestations

Mallol et al. (2010) [28]

165,917

Multiple countries in South America, multiple cities at different altitudes and environments

Questionnaire evaluating asthma prevalence and clinical manifestations

Del-Rio-Navarro et al. (2020) [34]

77,179

Mexico, 14 cities at different altitudes

Questionnaire to evaluate asthma prevalence