A 10-country survey identifies a striking disconnect between what people know about polluted air and how they respond to it.
Study: Public responses about air quality in the world’s ten most populous countries. Image Credit: Lane V. Erickson / Shutterstock
In a recent study accepted for publication in the journal Nature Communications, researchers assessed public responses to air quality in the world’s 10 most populous countries. They found that participants residing in regions with higher concentrations of particulate matter ≤2.5 micrometers in diameter (PM2.5) were less knowledgeable about outdoor air pollutants but reported greater concern and engaged more frequently in protective behaviors. These associations varied across demographic groups.
Respondents with conservative political ideologies were also more concerned, perceived greater air pollution-related health risks, and showed greater support for measures to reduce air pollution, despite having less knowledge about air pollution. Although their overall adjusted practice scores were not significantly higher, the relationship between PM2.5 exposure and protective practices was stronger among conservatives. These findings can help policymakers identify people who need greater support and develop more targeted interventions to improve public health.
People residing in densely populated regions tend to be more exposed to air pollutants than those living in less densely populated areas. Activities such as increased residential heating, land use for infrastructure development, and increased vehicular transport and traffic congestion can significantly degrade air quality, so air pollution is usually higher in urban areas. Exposure to air pollution contributes to disease, mental health disorders, cognitive dysfunction, and even death. This is why it is crucial to understand population-level perceptions and responses to air pollution.
Most previous studies have either included case studies or convenience samples from limited geographical regions. Although national policies exist, administrative bodies often implement their own measures. Large-scale assessments can reveal overarching patterns across countries and support more equitable air pollution prevention and control strategies while accounting for local differences.
About the study
In this cross-sectional study, researchers examined how people perceive and respond to ambient air pollution in the 10 most populous countries of the world. They aimed to determine whether exposure level was associated with people’s perceptions and responses to air pollution.
The team used quota sampling to include 10,618 individuals living across 1,372 localities in the United States (US), Brazil, Bangladesh, China, India, Indonesia, Nigeria, Mexico, Russia, and Pakistan. People aged ≥18 years or older who had lived in their country for at least 1 year were recruited via Qualtrics between April and August 2021 in 9 countries.
In China, recruitment took place from June to September 2021 via face-to-face interviews and SoJump.com. Participants responded to the knowledge, attitudes, perceptions, practices, and emotions (KAPPE) domains regarding air pollution.
The 10-item Air Quality Knowledge (AQIQ) questionnaire helped the researchers assess respondents’ knowledge regarding air quality. The final sample was obtained after 31% of the 15,017 initially recruited participants were excluded for failing quality-control checks.
The team used multivariable ordinary least-squares regression models to evaluate associations between PM2.5 concentrations and KAPPE domains regarding air quality. The mean locality-level exposure during 2019–2021 was considered for analysis. All respondents within the same locality were assigned this three-year average.
The researchers weighted the data to account for differences between the sample and national education benchmarks. They also explored whether population demographics modified these associations to identify the most vulnerable population subgroups.
Results
The team found inverse associations between air quality knowledge and PM2.5 exposure, but positive associations between PM2.5 exposure and protective practices and concern. The association with attitudes was positive but only marginally significant, while PM2.5 was not significantly associated with risk perceptions overall.
Demographic factors significantly influenced the results. Individuals living in regions with poor air quality were less knowledgeable regarding air pollutants. In particular, each 50 µg/m³ increase in PM2.5 was associated with a 0.2-point lower knowledge score. Females, participants younger than 40 years, smokers, conservatives, and those without a bachelor’s degree had lower overall knowledge scores.
The inverse association between PM2.5 and knowledge was stronger among younger participants, those without bachelor’s degrees, unemployed participants, and smokers. Country averages suggested that Bangladesh, Nigeria, and Pakistan contributed substantially to this pattern.
Rural residence, being single, and unemployment were each associated with lower support for anti-pollution measures.
There seemed to be opposing country-level patterns in the associations between air quality and residents’ perceptions of it. Females and conservatives reported stronger perceptions of pollution sources and health risks, while females, younger participants, and conservatives expressed greater concern.
At the country level, India and Pakistan recorded the highest concern scores. Bangladesh, India, and Pakistan, which had the highest mean PM2.5 concentrations, also reported the most frequent protective practices. Every 50 µg/m³ increase in PM2.5 concentration was associated with a 1.7-point higher practice score. However, rural residents adopted protective practices less frequently, while smokers, single people, unemployed participants, and rural residents reported weaker risk perceptions.
Taken together, smoking was associated with lower knowledge and weaker risk perceptions but not with significantly lower adjusted practice scores. The inverse association between PM2.5 exposure and knowledge was stronger among younger people, those without bachelor’s degrees, unemployed participants, and smokers. The overall associations between respondents’ attitudes and knowledge and PM2.5 exposure were modest, whereas those with protective practices and concern were more pronounced.
Conclusions
The findings provide a snapshot of how individuals differing in age, gender, education, residence type, and political ideology view and respond to outdoor air quality. Since the study largely comprised urban populations, increasing rural representation in future studies could broaden the applicability of the findings and help policymakers develop more equitable interventions across different settings to reduce exposure to air pollutants and related health risks. Health authorities could develop more community-led initiatives and educational materials for younger people and those without bachelor’s degrees to improve awareness.
Because the study was cross-sectional, it cannot establish that PM2.5 exposure caused differences in knowledge, concern, or behavior. The findings may also reflect unmeasured influences such as local and national policies or media coverage. Researchers should also consider sex-related disparities and use longitudinal studies to explore temporal patterns and potential causal relationships between PM2.5 concentrations and KAPPE domains. Future research should also assess personal exposure and short-term pollution peaks that the locality-level three-year averages cannot capture.
