Evaluating the 35°C wet-bulb temperature adaptability threshold for young, healthy adults (PSU HEAT)

A wet-bulb temperature of 35°C has been theorized to be the limit to human adaptability to extreme heat, a growing concern in the face of continued and predicted accelerated climate change. While this theorized threshold is based in physiological principles it has not been tested using empirical data. This study examined the critical wet-bulb temperature (Twb, crit) at which heat stress becomes uncompensable in young, healthy adults performing tasks at modest metabolic rates mimicking basic activities of daily life. Across six experimentally determined environmental limits, no subject's Twb, crit reached the 35°C limit and all means were significantly lower than the theoretical 35°C threshold. Mean Twb, crit values were relatively constant across 36-40°C humid environments and averaged 30.55±0.98 °C but progressively decreased (higher deviation from 35°C) in hotter, dry ambient environments. Twb, crit was significantly associated with mean skin temperature (and a faster warming rate of the skin) due to larger increases in dry heat gain in the hot-dry environments. As sweat rates did not significantly differ among experimental environments, evaporative cooling was outpaced by dry heat gain in hot-dry conditions, causing larger deviations from the theoretical 35°C adaptability threshold. In summary, a wet-bulb temperature threshold cannot be applied to human adaptability across all climatic conditions and where appropriate (high humidity), that threshold is well below 35°C.

Validity and Reliability of a Protocol to Establish Human Critical Environmental Limits (PSU HEAT)

The PSU HEAT protocol has been used to determine critical environmental limits, i.e., those combinations of ambient temperature and humidity above which heat stress becomes uncompensable and core temperature rises continuously. However, no studies have rigorously investigated the reliability and validity of this experimental protocol. Here, we assessed the (1) between-visit reliability and (2) validity of the paradigm. Twelve subjects (5M/7W; 25±4 yr) completed a progressive heat stress protocol during which they walked on a treadmill (2.2 mph, 3% gradient) in a controllable environmental chamber. After an equilibration period, either dry-bulb temperature (Tdb) was increased every 5 min while ambient water vapor pressure (Pa) was held constant (Tcrit experiments) or Pa was increased every 5 min while Tdb was held constant (Pcrit experiments) until an upward inflection in gastrointestinal temperature (Tgi) was observed. For reliability experiments, 11 subjects repeated the same protocol on a different day. For validity experiments, 10 subjects performed a Tcrit experiment at their previously determined Pcrit or vice versa. The between-visit reliability (intraclass correlation coefficient, ICC) for critical environmental limits was 0.98. Similarly, there was excellent agreement between original and validity trials for Tcrit (ICC = 0.95) and Pcrit (ICC = 0.96). Further, the wet-bulb temperature at the Tgi inflection point was not different during reliability (p = 0.78) or validity (p = 0.32) trials compared to original trials. These findings support the reliability and validity of this experimental paradigm for the determination of critical environmental limits for maintenance of human heat balance.

Critical environmental limits for young, healthy adults (PSU HEAT)

Critical environmental limits are those combinations of ambient temperature and humidity above which heat balance cannot be maintained for a given metabolic heat production, limiting exposure time and placing individuals at increased risk of heat-related illness. The aim of the present study was to establish those limits in young (18-34 yr) healthy adults during low-intensity activity approximating the metabolic demand of activities of daily living. Twenty-five (12 men/13 women) subjects were exposed to progressive heat stress in an environmental chamber at two rates of metabolic heat production chosen to represent minimal activity (MinAct) or light ambulation (LightAmb). Progressive heat stress was performed with either (1) constant dry-bulb temperature (Tdb) and increasing ambient water vapor pressure (Pa) (Pcrit trials; 36, 38, or 40 °C), or (2) constant Pa and increasing Tdb (Tcrit trials; 12, 16, or 20 mmHg). Each subject was tested during MinAct and LightAmb in 2-3 experimental conditions in random order, for a total of 4-6 trials per participant. Higher metabolic heat production (p < 0.001) during LightAmb compared to MinAct trials resulted in significantly lower critical environmental limits across all Pcrit and Tcrit conditions (all p < 0.001). These data, presented graphically herein on a psychrometric chart, are the first to define critical environmental limits for young adults during activity resembling those of light household tasks or other activities of daily living, and can be used to develop guidelines, policy decisions, and evidence-based alert communications to minimize the deleterious impacts of extreme heat events.

Climate Change Inaction and Meaning

Continuing growth, insofar as it increases human environmental impact, is in conflict with the environment. ‘Green growth’, if it increases the absolute size of the economy, is an oxymoron. Environmental limits are discountenanced, a pretence made possible because they are difficult to specify in advance. The consequent weakness in public discourse, both moral and intellectual, has worsened into contradiction as it has become ever more studiously unadmitted. It is obscured with language that is misleading or self-contradictory, and even issues from institutions that exist (and are relied upon) to respect correctness. At its most conforming it gives rise to overshoot, by which statements meant to sound authoritative are in fact open to ridicule. Such untruthfulness perpetuates climate change inaction, and in a kind of direct action those using such language, contrary to their public or professional duty, could be asked to justify themselves in plain English.

Analysis of key criteria and requirements in implementing green procurement for green construction projects in Malaysia

Construction industry is one key driver in stimulating Malaysia’s economic growth. Green procurement is known as procurement that is consistent with the principles of sustainable development, such as ensuring a strong, healthy and just society, living within environmental limits and promoting good governance. Malaysian government has published a standard guideline of green procurement known as Government Green Procurement (GGP) guideline; however, it does not merely used for the construction development. Hence, this paper aims to analyse the criteria and requirements to implement green procurement for construction projects. Questionnaires were distributed to 60 respondents, comprising of project stakeholders that has experience in the development of green construction projects. Limiting to category commercial and office building projects only, hence, the respondents’ population was drawn using purposive method. The analysis uses descriptive statistics via mean score, and the standard deviation was used to measure the variables and the mean’s dispersion. It is revealed that all of the criteria stated are important and one or more criteria are more important than the rest. This study recommends that the government focus on these criteria to help implement green procurement for green construction projects in Malaysia.

Social Policy Without Growth: Moving Towards Sustainable Welfare States

Growth-dependent welfare states contribute to climate emergency. The ecological economics, degrowth, and sustainable welfare literatures demonstrate that to re-embed Western production and consumption patterns in environmental limits, an encompassing social-ecological transformation would need to be initiated very soon. This article focuses on the potential roles of the welfare state and social policy in this transformation, applying the concepts of ‘sustainable welfare’ and ‘safe-operating space’. Based on two Swedish studies, it also provides an empirical analysis of the popularity of selected eco-social policies designed to steer the economy and society towards this space: maximum and basic incomes, taxes on wealth and meat, as well as working time reductions. In analogy to the historical role of the state in reconstituting the welfare-work nexus in the post-WWII era and its present engagement in the context of the Covid-19 crisis, it is argued that a more interventionist state is required to grapple with climate emergency.

Unintended Consequences: Unknowable and Unavoidable, or Knowable and Unforgivable?

Recognizing that there are multiple environmental limits within which humanity can safely operate, it is essential that potential negative outcomes of seemingly positive actions are accounted for. This alertness to unintended consequences underscores the importance of so called “nexus” research, which recognizes the integrated and interactive nature of water, energy and food systems, and aims to understand the broader implications of developments in any one of these systems. This article presents a novel framework for categorizing such detrimental unintended consequences, based upon how much is known about the system in question and the scope for avoiding any such unintended consequences. The framework comprises four categories (Knowable and Avoidable; Knowable and Unavoidable; Unknowable and Avoidable, and Unknowable and Unavoidable). The categories are explored with reference to examples in both the water-energy-food nexus and planetary boundary frameworks. The examples highlight the potential for the unexpected to happen and explore dynamic nature of the situations that give rise to the unexpected. The article concludes with guidance on how the framework can be used to increase confidence that best efforts have been made to navigate our way toward secure and sustainable water, energy and food systems, avoiding and/or managing unintended consequences along the way.