Long-term exposure to ambient air pollution and asthma symptom score in the CONSTANCES cohort

BACKGROUND

The asthma symptom score allows to consider asthma as a continuum and to investigate its risk factors. One previous study has investigated the association between asthma score and air pollution and only for nitrogen dioxide (NO₂). We aimed to study the associations between particulate matter with an aerodynamic diameter lower than 2.5 µm (PM_2.5), black carbon (BC) and NO₂ and the asthma symptom score in adults from CONSTANCES, a French population-based cohort.

METHODS

Asthma symptom score (range: 0-5) was based on the number of five self-reported symptoms of asthma in the last 12 months. Annual individual exposure to PM_2.5, BC and NO₂ was estimated at participants' residential address using hybrid land-use regression models. Cross-sectional associations of each pollutant with asthma symptom score were estimated using negative binomial regressions adjusted for age, sex, smoking status and socioeconomic position. Associations with each symptom were estimated using logistic regression. The effect of BC independent of total PM_2.5 was investigated with a residual model.

RESULTS

Analyses were conducted on 135 165 participants (mean age: 47.2 years, 53.3% women, 19.0% smokers, 13.5% ever asthma). The ratio of mean score was 1.12 (95% CI 1.10 to 1.14), 1.14 (95% CI 1.12 to 1.16) and 1.12 (95% CI 1.10 to 1.14) per one IQR increase of PM_2.5 (4.86 µg/m³), BC (0.88 10^-5 m^-1) and NO₂ (17.3 µg/m³). Positive and significant associations were also found for each asthma symptom separately. BC effect persisted independently of total PM_2.5.

CONCLUSION

Exposure to each pollutant was associated with increased asthma symptom score in adults. This study highlights that BC could be one of the most harmful particulate matter components.

Toward setting public health guidelines for chemicals in indoor settled dust?

Indoor settled dust may result in substantial human exposure to chemicals, especially by ingestion following hand-to-mouth or hand-to-object-to-mouth contact. As with other environmental media related to exposure, dust may thus be subject to regulation. An international scientific workshop was convened in Paris in September 2019 firstly to assess the relevance for public health of setting guidelines for indoor settled dust, and secondly to discuss scientific and technical challenges related to such guidelines. The main discussions and conclusions, with consensus achieved, are reported herein. Discussions concerned general considerations, objectives and definitions, relevance for a health-based guideline, units of measure, and finally derivation of the guideline. These points should be addressed when considering an indoor settled dust guideline as part of a policy to reduce exposure indoors to a given chemical or group of chemicals.

Indoor mould exposure, asthma and rhinitis: findings from systematic reviews and recent longitudinal studies

Starting from the Institute of Medicine (IOM) and World Health Organization (WHO) reports, this review provides an overview of the literature published from 2006 to 2017 on the associations between indoor mould exposure and asthma and rhinitis separately in children and adults with a focus on longitudinal epidemiological studies.A systematic search of peer-reviewed literature was performed, including systematic reviews and meta-analyses, longitudinal, incident case-control and panel studies. 61 publications were identified reporting visible mould or mould odour or quantitative assessment of culturable fungi or mould species.In children, visible mould and mould odour were associated with the development and exacerbations of asthma, providing sufficient evidence of a causal relationship. Results from population-based studies in adults were too few and divergent to conclude at more than a limited level of evidence. Exposure to mould in a work building was associated with the incidence and exacerbations of occupational asthma, and we concluded at a sufficient evidence for an association. Systematic reviews, meta-analyses and longitudinal studies on the relationships between mould exposure and allergic rhinitis provide sufficient evidence of an association.This review extended the conclusions of the IOM and WHO reports, and highlighted the need for further longitudinal studies on asthma in adults, and on rhinitis.