Impact of Desert Dust on Air Quality: What is the Meaningfulness of Daily PM Standards in Regions Close to the Sources? The Example of Southern Tunisia

Desert dust is now recognized as a major health hazard. However, there still exists a lack of measurements of desert dust atmospheric loads in regions located in the vicinity of the major desert areas, where a growing part of the world population is living. Dust emission is a sporadic and intense phenomenon so that the classical air quality standards should not be appropriate to reflect the real population exposure to desert dust. In order to give some insight to answer this question, PM10 concentrations were continuously measured at a five-minute time step in southern Tunisia from February 2014 to February 2019. The daily and annual PM10 concentrations were first discussed according to the Tunisian air quality standards: In this relatively remote area, close to dust source, these standards were respected at the annual, but no longer at the daily scale. Measurements performed at a high temporal resolution (five minutes) allowed to discriminate the different situations that led to exceed Tunisian daily standards in southern Tunisia. In particular, intense (five-minute PM10 concentrations up to more than 1500 µg m−3) and short-lived (a few hours) dust outbreaks were regularly observed. This result raises the question of the necessity of defining specific air quality standards at the sub-daily scale in countries affected by intense desert dust outbreaks.

The effect of Asian dust on asthma by socioeconomic status using national health insurance claims data in Korea

CONTEXT

Asian dust events are associated with increased asthma incidence, asthma exacerbation, decreased lung function and increased risk for hospitalization.

OBJECTIVE

The purpose of this study was to evaluate the effect of Asian dust events on asthma exacerbation by socioeconomic status using national health insurance claims data.

MATERIALS AND METHODS

A case-crossover design was used to analyze asthma-related national health insurance claims, air pollutant and climate data from 2007 to 2013 in Seoul and Incheon, Korea. We stratified our analysis by socioeconomic status (health insurance versus medical aid subscribers) and calculated the maximum air pollutant levels and average climate values per day. The number of asthma-related visits to medical institutions per day was compared between "event" and "control" days.

RESULTS

Compared with "control days", the average number of asthma-related visits to medical institutions decreased on "event" days and increased 1-5 d thereafter. The number of visits by health insurance subscribers also decreased on "event" days and increased 1-5 d thereafter, while the number of visits by medical aid subscribers did not change on "event" days but increased 1-4 d thereafter.

DISCUSSION AND CONCLUSION

Our study confirms that Asian dust events result in an increased number of asthma-related visits to medical institutions. This effect differed by socioeconomic status.