Size and site dependent biological hazard potential of particulate matters collected from different heights at the vicinity of a building construction

How do environmental and operational factors impact particulate matter dynamics in building construction? - Insights from real-time sensing

Construction activities are major contributors to particulate matter (PM) pollution, posing significant risks to workers and nearby populations. However, PM mitigation strategies in the complex nature of construction environments remain underexplored, with limited understanding of how environmental and operational factors jointly influence PM dynamics in real-world settings. This study employs high-resolution real-time monitoring to investigate PM1, PM2.5, and PM10 interactions within an active construction site, focusing on the roles of environmental and operational drivers. Over 28,000 measurements were collected from construction zones, complemented by external reference points. The findings reveal that smaller particles (PM1 and PM2.5) serve as critical intermediaries influencing larger particles (PM10). PM10 concentrations peaked at 1763.37 μg/m3, far exceeding regulatory thresholds. Temperature influenced PM10 primarily through its effect on PM2.5 (57 %), while construction scenarios had 72 % of their impact on PM10 mediated via PM2.5. Distinct PM relationships emerged based on activity types and worker proximity to sensors, with hazardous PM levels persisting in 81.61 % of low-activity periods, highlighting the risks of residual exposure even without active construction. This study underscores the importance of on-site, multi-indicator monitoring systems to capture dynamic PM variations and identify high-risk scenarios. By providing a detailed understanding of PM interactions in active construction settings, these findings offer a robust foundation for developing targeted mitigation strategies and advancing air quality management in construction environments.

Albumin conjugation promotes arsenic trioxide transport through alkaline phosphatase-associated transcytosis in MUC4 wildtype pancreatic cancer cells

Pancreatic cancer (PC) has a poor prognosis due to chemotherapy resistance and unfavorable drug transportation. Albumin conjugates are commonly used as drug carriers to overcome these obstacles. However, membrane-bound glycoprotein mucin 4 (MUC4) has emerged as a promising biomarker among the genetic mutations affecting albumin conjugates therapeutic window. Human serum albumin-conjugated arsenic trioxide (HSA-ATO) has shown potential in treating solid tumors but is limited in PC therapy due to unclear targets and mechanisms. This study investigated the transport mechanisms and therapeutic efficacy of HSA-ATO in PC cells with different MUC4 mutation statuses. Results revealed improved penetration of ATO into PC tumors through conjugated with HSA. However, MUC4 mutation significantly affected treatment sensitivity and HSA-ATO uptake both in vitro and in vivo. Mutant MUC4 cells exhibited over ten times higher IC50 for HSA-ATO and approximately half the uptake compared to wildtype cells. Further research demonstrated that ALPL activation by HSA-ATO enhanced transcytosis in wildtype MUC4 PC cells but not in mutant MUC4 cells, leading to impaired uptake and weaker antitumor effects. Reprogramming the transport process holds potential for enhancing albumin conjugate efficacy in PC patients with different MUC4 mutation statuses, paving the way for stratified treatment using these delivery vehicles.

Characterization of size-differentiated airborne particulate matter collected from indoor environments of childcare facilities

Inhalation of particulate matter (PM) present in indoor atmospheres has been associated with poor health and wellbeing of occupants. Here we report the characteristics of airborne PM collected from twenty-two air-conditioned childcare centres in Singapore. Airborne PM were collected using cascade impactors and characterized for morphology, elemental composition, endotoxin levels, ability to generate abiotic reactive oxygen species, and oxidative stress-dependent cytotoxicity in BEAS-2B cell lines. The mass concentrations of ultrafine particles (PM0.06-1) were more abundant than that of larger particles (PM1-4, PM4-20, and PM20-35 particles). PM20-35 and PM4-20 were irregularly shaped particles, PM1-4 particles had membranous flaky structures and PM0.06-1 particles were pseudo-spherical with the occasional presence of crystalline structures. Carbonaceous matter dominated PM20-35 particles, and the abundance of inorganic salts, iron and sulfur increased with decreasing PM size. Measured endotoxin levels were especially higher in PM4-20 particles. Compared to other particle size fractions, PM0.06-1 particles generated the highest ROS and were also the most potent in generating intracellular ROS in BEAS-2B cell lines. However, total mass concentrations, elemental compositions, abiotic responses, and PM collected from centres with split air-conditioning systems and no active outdoor air supply (SAC) were not statistically different compared with PM collected from centres with air conditioning with mechanical ventilation (ACMV). In conclusion, our study showed obvious distinctions in mass concentrations, morphology, elemental compositions, and cytotoxic potential of different sized particles collected from childcare centres, where the smallest particles (PM0.06-1) exhibited higher hazard potential.

Measurement and Monitoring of Particulate Matter in Construction Sites: Guidelines for Gravimetric Approach

Studies on particulate matter (PM) from construction activities are still at an early stage. Thus, there is still no consensus on standardized experimental methods for monitoring PM in construction sites, which impedes the advancement of knowledge on this subject. This work proposes guidelines for measuring and monitoring the concentration of suspended PM and the annoyance generated by sedimented particles on construction sites in urban areas. These guidelines aim to reduce the variability and uncertainties that exist during the PM sampling processes at construction sites. This study adopts a literature review strategy in order to update the available scientific literature based on empirical evidence obtained in experimental PM studies and relevant documents from government agencies. The proposed guidelines were applied in a study protocol for gravimetric monitoring PM and annoyance tracking generated by sedimented particles using sticky pads. As a result, this article details sampling techniques, procedures, and instruments, focusing on gravimetric sampling, highlighting their characteristics compared to other monitoring approaches. Additionally, it points out a series of parameters for the measurement and monitoring of PM. This paper seeks to support future researchers in this area, inform decision making for experimental sampling, and provide a benchmark for measuring and monitoring PM at construction sites.

Personal level exposure and hazard potential of particulate matter during haze and non-haze periods in Singapore

Severe haze episodes originating from biomass burning are common in Southeast Asia. However, there is a paucity of data on the personal exposure and characteristics of Particulate Matter (PM) present in ambient air during haze and non-haze periods. Aims of this study were to monitor 24 h ambulatory exposure to PM among school children in Singapore; characterize haze and non-haze PM for their physicochemical properties, cytotoxicity and inflammatory potential, using bronchial epithelial cell culture model (BEAS-2B). Forty-six children had ambulatory PM exposure monitored using portable Aethalometer and their hourly activity recorded. The mean (±SE) PM exposure on a typical school day was 3343 (±174.4) ng/m³/min. Higher PM exposure was observed during haze periods and during commuting to and from the school. Characterization of PM collected showed a drastic increase in the proportion of ultrafine particle (UFP) in haze PM. These PM fraction showed higher level of sulphur, potassium and trace metals in comparison to those collected during non-haze periods. Dose dependent increases in abiotic reactive oxygen species generation, activation of NF-κB and cytotoxicity were observed for both haze and non-haze PM. Generally, haze PM induced significantly higher release of IL-6, IL-8 and TNFα by BEAS-2B cells in comparison to non-haze PM. In summary, this study provides experimental evidence for higher PM exposure during haze period which has the potential to elicit oxidative stress and pro-inflammatory cytokine release from airway epithelial cells.

Combined toxicity of prevalent mycotoxins studied in fish cell line and zebrafish larvae revealed that type of interactions is dose-dependent

While, Aflatoxin B₁ (AFB₁), deoxynivalenol (DON) and zearalenone (ZEN) are the most prevalent mycotoxins co-existing in grain products and animal feeds, little is known about their combinatorial toxicities on aquatic life-forms. We studied the individual and combined effects of these mycotoxins in a fish cell line (BF-2) and zebrafish larvae (wild-type and transgenic). The types of interactions in mycotoxins combinations on cell viability were determined by using Chou-Talalay model. Induction of oxidative stress pathway in mycotoxins-exposed BF-2 cells was assessed using high content screening (HCS). Mycotoxin-exposed wild-type zebrafish larvae were examined for mortality and morphological abnormalities and transgenic zebrafish larvae (expressing DsRed in the liver) were imaged using HCS and examined for liver abnormalities. Results showed that the cytotoxicity of mycotoxins in a decreasing order was AFB₁>DON>ZEN, however, the highest mortality rate and liver damage in zebrafish were observed for AFB₁ followed by ZEN. AFB₁+DON and AFB₁+ZEN synergistically enhanced the toxic effects on BF-2 cells and zebrafish while DON+ZEN showed antagonism. Interestingly, in the tertiary combination, the synergism seen at lower individual concentrations of mycotoxins progressively turned to an overall antagonism at higher doses. The results provide a scientific basis for the necessity to consider co-exposure when formulating risk-management strategies.

A light-assisted in situ embedment of silver nanoparticles to prepare functionalized fabrics

This article presents a simple, one-step, in situ generation of silver nanoparticle-functionalized fabrics with antibacterial properties, circumventing the conventional, multistep, time-consuming methods. Silver nanoparticle formation was studied with a library of capping agents (branched polyethylenimine [BPEI] of molecular weight [Mw] 10,000 and 25,000, polyvinylpyrrolidone, polyethylene glycol, polyvinylalcohol and citrate) mixed with silver nitrate. The mixture was then exposed to an assortment of light wavelengths (ultraviolet, infrared and simulated solar light) for studying the light-assisted synthesis of nanoparticles. The formation of nanoparticles corresponded with the reducing capabilities of the polymers wherein BPEI gave the best response. Notably, the irradiation wavelengths had little effect on the formation of the nanoparticle when the total irradiation energy was kept constant. The feasibility of utilizing this method for in situ nanoparticle synthesis on textile fabrics (towel [100% cotton], gauze [100% cotton], rayon, felt [100% polyester] and microfiber [15% nylon, 85% polyester]) was verified by exposing the fabrics soaked in an aqueous solution of 1% (w/v) AgNO3 and 1% (w/v) BPEI (Mw 25,000) to light. The formation of nanoparticles on fabrics and their retention after washing was verified using scanning electron microscopy and quantified by inductively coupled plasma optical emission spectrometry. The functional property of the fabric as an antibacterial surface was successfully demonstrated using model bacteria such as Staphylococcus aureus, Enterococcus faecalis and Escherichia coli. The successful generation of silver nanoparticle-functionalized textile fabrics without the use of caustic chemicals, solvents and excessive heating presents a major step towards realizing a scalable green chemistry for industrial generation of functionalized fabrics for a wide range of applications.

Particulate matter from indoor environments of classroom induced higher cytotoxicity and leakiness in human microvascular endothelial cells in comparison with those collected from corridor

We investigated the physicochemical properties (size, shape, elemental composition, and endotoxin) of size resolved particulate matter (PM) collected from the indoor and corridor environments of classrooms. A comparative hazard profiling of these PM was conducted using human microvascular endothelial cells (HMVEC). Oxidative stress-dependent cytotoxicity responses were assessed using quantitative reverse transcriptase polymerase chain reaction (RT-PCR) and high content screening (HCS), and disruption of monolayer cell integrity was assessed using fluorescence microscopy and transwell assay. Scanning electron microscopy (SEM) coupled with energy-dispersive X-ray spectroscopy (EDX) analysis showed differences in the morphology and elemental composition of PM of different sizes and origins. While the total mass of PM collected from indoor environment was lower in comparison with those collected from the corridor, the endotoxin content was substantially higher in indoor PM (e.g., ninefold higher endotoxin level in indoor PM_8.1-20 ). The ability to induce oxidative stress-mediated cytotoxicity and leakiness in cell monolayer were higher for indoor PM compared to those collected from the corridor. In conclusion, this comparative analysis suggested that indoor PM is relatively more hazardous to the endothelial system possibly because of higher endotoxin content.

Individual and combined effects of Aflatoxin B1, Deoxynivalenol and Zearalenone on HepG2 and RAW 264.7 cell lines

To understand the combinatorial toxicity of mycotoxins, we measured the effects of individual, binary and tertiary combinations of Aflatoxin B₁ (AFB₁), Deoxynivalenol (DON) and Zearalenone (ZEN) on the cell viability and cellular perturbations of HepG2 and RAW 264.7 cells. The nature of mycotoxins interactions was assessed using mathematical modeling (Chou-Talalay). Mechanisms of cytotoxicity were studied using high content screening (HCS) that probed cytotoxicity responses, such as changes in intracellular reactive oxygen species (ROS), mitochondrial membrane potential (MMP), intracellular calcium ([Ca²⁺]_i) flux, and cell membrane damage. Our results showed that individual cytotoxicity of mycotoxins in a decreasing order was DON>AFB₁>ZEN. Varying combinations of mycotoxins at differing concentrations showed different types of interactions. Most of the mixtures showed increasing toxic effects-synergism and/or addition while antagonistic effects were observed with combination of AFB₁+ZEN. Generally, combination of mycotoxins showed significantly increased intracellular ROS production and [Ca²⁺]_i flux, and decreased MMP in both cell lines, showing that the synergistic and additive effects of mycotoxin combination originate from perturbations of multiple cellular functions. Additionally, this study demonstrated the applicability of HCS for gaining mechanistic understanding on the toxicity of individual as well as combinatorial mycotoxins, and also provided scientific bases for formulating regulatory policies.