Relationship between air quality and asthma-related emergency hospital admissions in Mexico City 2017-2019

Previous studies found exposure to air pollution leads to exacerbations of asthma in paediatric and adult patients and increases asthma-related emergency hospital admissions (AREHA).

AREHAs and levels of air pollutants (PM₁₀, PM_2.5 and NO₂) were obtained from Mexico City for the period 2017-2019. A time-series approach was used to explore the relationship between air pollutants and AREHA. Relative risks of AREHA were estimated using a negative binomial regression in young children (less than 5 years) and adults (greater than 18 years).

There was a positive association between AREHA and PM₁₀, PM_2.5 and NO₂ in adults, which remained after mutual adjustment for these pollutants. The relative risk (RR) of admission in adults increased by 3% (95% CI 1% to 4%) for a 10 µg/m³ increase in PM₁₀, 1% (0.03% to 3%) for a 5 µg/m³ increase in PM_2.5 and by 1% (0.06% to 2%) for a 5 µg/m³ increase in NO₂. In contrast, in young children, AREHAs were negatively associated with PM₁₀ after adjustment for NO₂ (RR 0.97 (0.95 to 0.99) for a 10 µg/m³ and with NO₂ after adjustment for PM₁₀ and PM_2.5 (RR 0.98 (0.96 to 0.99) and 0.97 (0.96 to 0.99), respectively, for a 5 µg/m³ increase in NO₂). AREHAs in children were not associated with PM_2.5 after adjustment for NO₂.

Ambient air pollution, within the previous week, was associated with emergency hospital admissions for asthma to public hospitals in adults in Mexico City. The relationship in children was less consistent. Further work is needed to explore why differences between adults and children exist to inform appropriate interventions to benefit public health.