Relationships between environmental factors and lung function of asthmatic subjects in south east Queensland, Australia

Outdoor Mold and Respiratory Health: State of Science of Epidemiological Studies

BACKGROUND

Fungal spores are the predominant biological particulates in outdoor air. However, in contrast to pollens or outdoor air pollution, little is known about their respiratory health risks.

OBJECTIVES

The objectives were to conduct the first review of epidemiological studies on the short- and long-term effects of outdoor mold exposure on respiratory health in children and adults.

METHODS

Health outcomes included asthma, lung function, and rhinitis. Cross-sectional and longitudinal epidemiological studies using quantitative measures of outdoor mold exposure (optical microscopy, culture-based methods) were selected, providing that important confounding factors including temporal trends or meteorological factors were accounted for. A systematic literature search was performed up to June 2020, leading to the selection of 37 publications.

RESULTS

Most studies were longitudinal and investigated short-term effects. There is evidence of an association between outdoor fungal exposure and an increase in asthma exacerbation among children for total spores, 2 phyla (ascomycetes, basidiomycetes), and 2 taxa (Cladosporium, Alternaria). A few studies also suggested an association for Coprinus, Ganoderma, Aspergillus-Penicillium, Botrytis, and Epicoccum in children, but this needs to be confirmed. Some studies reported mold associations with rhinitis, lung function, and among adults, but these were few in number or inconsistent.

DISCUSSION

Further ecological studies in different regions that measure exposure to all taxa over several years are required to better understand their impact on rhinitis, asthma exacerbations and lung function. Larger panel studies are necessary to identify threshold effects in susceptible individuals. Finally, further research should assess the long-term effects of outdoor mold.

Outdoor fungal spores and acute respiratory effects in vulnerable individuals

BACKGROUND

Many outdoor fungal spores are ubiquitous, respirable and possibly allergenic. They may contribute to asthma symptoms; however, little is known about their effects on respiratory function.

OBJECTIVE

To investigate if outdoor fungal spore levels were associated with lung function or airway inflammation, and whether fungal sensitization or current asthma modified any associations.

METHODS

Cross-sectional associations between same day (Lag0) and cumulative 3-day lagged (Lag0-3) counts of 12 outdoor fungal spore taxa and pre-bronchodilator spirometry (FEV₁, FVC, FEF_25%-75%), bronchodilator response (BDR) and airway inflammation (fractional exhaled nitric oxide (FeNO) and exhaled breath condensate (EBC) nitrogen oxides (NOx) and pH were investigated in 936 Melbourne Atopy Cohort Study participants during September 2009 to December 2011. Generalized linear models were used to quantify associations with lung function, FeNO and EBC pH; generalized estimating equations for BDR; and ordinal logistic regression for EBC NOx. Models were adjusted for age, sex, height, temperature, relative humidity, grass pollen and sample storage time. Potential effect modification by fungal sensitization and current asthma were examined using interaction terms.

RESULTS

Mixed associations were found. Higher levels of Ustilago/smuts were associated with lower lung function at Lag0 (FEV₁: 21ml [95%CI -36, -7]; FEF_25%-75%: 39ml [-65, -13]) and Lag0-3 (FEV₁: 9ml [-14, -4]; FEF_25%-75% -18ml [-27, -9]). Positive BDR was associated with Ustilago/smuts (Lag0 OR = 1.1 [1.04, 1.2]; Lag0-3 OR = 1.04 [1.02, 1.07]), Alternaria (Lag0 OR = 1.3 [1.0, 1.6]) and Drechslera (Lag0 OR = 1.1 [1.03, 1.2]). Higher EBC NOx was associated with Cladosporium (Lag0-3 OR = 1.1 [1.0, 1.2]), Alternaria (Lag0-3 OR = 1.1 [1.0, 1.3]). No associations were found with higher FeNO. In those with fungal sensitization, Ustilago/smuts and Drechslera were associated with lower FEV₁ and FVC; Cladosporium was associated with increased FEV₁, FVC and FEF_25%-75% but also with higher FeNO and lower EBC pH. In those with current asthma, Alternaria, Ustilago/smuts and Drechslera were associated with lower FEV₁, FVC, FEF_25-75% and EBC pH.

CONCLUSION

Exposure to outdoor fungal spores may be associated with lower lung function and increased airway inflammation, particularly in those with fungal sensitization and/or current asthma.

Characteristics of atmospheric bacterial and fungal communities in PM2.5 following biomass burning disturbance in a rural area of North China Plain

Biomass burning (BB) in North China Plain has been urgent issue in recent years due to the severe environmental impaction. Bacteria and fungi are ubiquitous in particulate matter. Their taxonomic composition, concentration, ecophysiological functions have potentially important implications in atmospheric biochemical cycle and human health. However, current knowledge about airborne microbes during biomass burning period is scant. Here we investigated bacterial and fungal community composition, abundance and potential function in Yucheng, the center of the North China Plain during summer harvest season in 2014. Monthly field observation suggested serious pollution with high concentration of PM_2.5 and water-soluble ions during biomass burning period. Elevated total bacterial and fungal concentration determined by real-time quantitative PCR was observed for samples during burning events. The predominant bacterial taxa were gram-negative, e.g. Acinetobacter, Cyanobacterium, Janthinobacterium, Massilia, Pseudomonas, accounted for 70.9% of total bacteria. The filamentous fungi Alternaria, Aspergillus, Cladosporium and Penicillium were predominant fungal genera. Metastats analysis showed significant disparity in terms of carbohydrate, amino acids metabolism, human and plant disease predicted by PICRUSt analysis between BB and non-BB events. Microbial community structure were mainly influenced by organic carbon and water-soluble ions (magnesium and potassium) suggested by redundancy analysis (RDA) and co-occurrence analysis. Our data yielded insights into microbial community dynamics following biomass burning disturbance. This study may provide potentially important reference for environmental, agricultural and health management.

Eucalyptus pollen allergy and asthma in children: a cross-sectional study in South-East Queensland, Australia

Objectives

To investigate Eucalyptus (gum tree) pollen allergy in children in relation to geography, particularly vegetation, and its relationship to asthma.

Methods

Males (n = 180) and females (n = 200) aged 9 to 14 participated. Some were healthy (asymptomatic), some had asthma, and some had other symptoms associated with atopy. School students were from three urban coastal schools and one school from a nearby semi-rural elevated area (range) near Brisbane, Australia. Coastal and range locations featured different distributions of Myrtaceae family vegetation (including Eucalyptus, Melaleuca, Leptospermum species). Skin prick test (SPT) responses to 15 commercial allergens were compared. As well, responses from coast versus range groups, and ‘asthma’ (n = 97) versus ‘healthy’ status (n = 107) groups, were compared.

Results

SPT responses (≥3mm wheal diameter) indicate that children with asthma are 31.1 times more likely to be allergic to Eucalyptus pollen extract (OR: 31.1; 95%CI 4.1- 235.7) compared to healthy children. Dust mite (p = .018), Eucalyptus (p = .046) and cockroach (p = .047) allergen SPT responses (wheals ≥3mm) were significantly greater in participants located on the coast versus range as determined by Fisher’s Exact Test (α .05). For each location, percentage of positive responses (wheals ≥3mm) was greatest for ‘dust mite’ (30.9%-46%), ‘cockroach’ (18.1% -35%) and ‘Bermuda grass’ (10.6%-19.4%).

Conclusions

The results support the hypothesis that proximity to Myrtaceae vegetation is related to positive SPT response and that Eucalyptus is an important allergen for children with asthma. Substantial response to olive allergen, in the absence of olive trees, suggests that the response may be driven by substances in other plants, perhaps Melaleuca quinquenervia, which abounds in coastal areas.

Implications

Response to Eucalyptus allergen indicates that changes in gardening practice in schools and public areas may be appropriate. The findings pose validity questions regarding the use of some commercial allergens due to cross-reactive responses and the sources of those responses.

School children's personal exposure to ultrafine particles in the urban environment

There has been considerable scientific interest in personal exposure to ultrafine particles (UFP). In this study, the inhaled particle surface area doses and dose relative intensities in the tracheobronchial and alveolar regions of lungs were calculated using measured 24-h UFP time series of school children personal exposures. Bayesian hierarchical modeling was used to determine mean doses and dose intensities for the various microenvironments. Analysis of measured personal exposures for 137 participating children from 25 schools in the Brisbane Metropolitan Area showed similar trends for all participating children. Bayesian regression modeling was performed to calculate the daily proportion of children's total doses in different microenvironments. The proportion of total daily alveolar doses for home, school, commuting, and other were 55.3%, 35.3%, 4.5%, and 5.0%, respectively, with the home microenvironment contributing a majority of children's total daily dose. Children's mean indoor dose was never higher than the outdoor's at any of the schools, indicating there were no persistent indoor particle sources in the classrooms during the measurements. Outdoor activities, eating/cooking at home, and commuting were the three activities with the highest dose intensities. Children's exposure during school hours was more strongly influenced by urban background particles than traffic near the school.

Observation of elevated fungal tracers due to biomass burning in the Sichuan Basin at Chengdu City, China

Fungal material (i.e., spores and fragments) is an important component of atmospheric aerosols. In order to examine the variability of fungal abundance in fine particles (PM(2.5)) during a biomass burning season, an intensive measurement campaign was conducted in the Sichuan Basin at Chengdu, a megacity in southwest China, in spring 2009. The aerosol samples were analyzed for carbonaceous species, including molecular tracers for biomass burning and fungal material, and water soluble ions. The results were interpreted with the help of principle component analysis, fire count maps, and the WRF model. Elevated concentrations of arabitol and mannitol were found with average concentrations of 21.5±16.6 ng m(-3) and 43.9±19.3 ng m(-3), respectively, which were unexpectedly higher than those measured in fine particles in any other study reported previously. Even higher concentrations were observed in cases with simultaneous enhancements in the biomass burning tracers levoglucosan and K(+). In the case of influence by pollution plumes from biomass burning regions, the fungal tracer concentrations reached maximum values of 79.6 ng m(-3) and 121.8 ng m(-3), coinciding with peak levels of levoglucosan and K(+). Statistically significant correlations were found between the simultaneously observed fungal tracers (arabitol and mannitol) and biomass burning tracers (levoglucosan and K(+)), suggesting that these species were emitted by co-located sources, and hence the elevated fungal tracers were likely associated with biomass burning activities.

Vegetation fires, particulate air pollution and asthma: a panel study in the Australian monsoon tropics

We examined the relationship between particulate matter (PM) <10 and <2.5 microns in diameter (PM10 and PM2.5) generated by vegetation fires and daily health outcomes in 251 adults and children with asthma over a 7-month period. Data were analysed using generalized estimating equations adjusted for potential environmental confounders, autocorrelation, weekends and holidays. PM10 ranged from 2.6 - 43.3 microg m-3and was significantly associated with onset of asthma symptoms, commencing oral steroid medication, the mean daily symptom count and the mean daily dose of reliever medication. Similar results were found for PM2.5. No associations were found with the more severe outcomes of asthma attacks, increased health care attendances or missed school/work days. These results help fill a gap in the evidence about the population health impacts of lower levels of pollution characteristic of deliberate landscape burning to control fuel loads versus the better documented risks of more intense and severely polluting wildfires.

Air pollution and its health impacts: the changing panorama

Urban air pollution levels are associated with increased mortality and cardiorespiratory morbidity. These health effects occur even at exposure levels below those stipulated in current air-quality guidelines, and it is unclear whether a safe threshold exists. Air pollution in Australia and New Zealand comes primarily from motor vehicle emissions, electricity generation from fossil fuels, heavy industry, and home heating using wood and coal. In individual patients a direct link between symptoms and air pollution exposure may be difficult to establish and may not change their clinical management. However, avoiding exposure during periods of peak pollution may be beneficial. Although there is some evidence that urban air pollution in Australia and New Zealand has been decreasing (through reduced car use, improved emission-control technology and use of more energy-efficient devices in the household and in industry), pollution levels are still unsatisfactory. Further reductions may prevent hundreds of cardiorespiratory hospital admissions and deaths each year.