Disinfection is a common practice to inhibit pathogens, yet success is limited by microbial adaptation and our poor knowledge of viral transmission, notably in the current COVID-19 pandemic. There is a need for alternative disinfection strategies and techniques that are adapted to the actual behavior of humans living in densely populated mega-cities. Here, high public circulation in shared passenger vehicles such as taxis, buses and personal cars represents a major risk of viral transmission due to confined space and commonly touched surfaces. Actual regulatory guidelines are not fully successful because they rely both on passengers’ willingness to wear face masks and on drivers’ willingness to disinfect cars after each shift or each ride with symptomatic individuals. Here we propose that passive solar heating, a sustainable technique that has been used in agronomy to kill weeds and soil pathogens, could inactivate the virus in vehicles during warm-to-hot weather within few minutes to half an hour at 50–60 °C. We measured temperatures in a white compact-size sedan left in a parking lot under direct sunlight. Air temperatures increased from 30 to 42–49 °C after 30 min and then reached a plateau at 52–57 °C after 90 min. Temperatures were about 3 °C higher in front versus back of the car and about 5 °C higher at face height compared to knee height. Since COVID-19 is inactivated in 30 min at 56 °C, our findings confirm that hot air generated passively by solar heating in enclosed spaces is a promising strategy of disinfection with benefits of no added costs, chemicals or worktime. Though this technique appears limited to hot climate, possible heating systems that work during parking time might be developed by vehicle makers to extend the technique to cold climates.

消毒是抑制病原体的常见做法，但成功受到微生物适应和我们对病毒传播了解甚少的限制，特别是在当前的 COVID-19 大流行中。需要适合生活在人口稠密的大城市中的人类实际行为的替代消毒策略和技术。在这里，出租车、公共汽车和私家车等共享客运车辆的高公共交通由于空间有限和经常接触的表面而成为病毒传播的主要风险。实际的监管指南并不完全成功，因为它们既依赖于乘客戴口罩的意愿，也依赖于司机在每次轮班或每次与有症状的人乘坐后对汽车进行消毒的意愿。在这里，我们提出，被动式太阳能加热是一种可持续技术，已在农学中用于杀死杂草和土壤病原体，在50-60°C的温度下，在温暖到炎热的天气下，几分钟到半小时内可以灭活车辆中的病毒。我们测量了停在停车场的一辆白色紧凑型轿车在阳光直射下的温度。30 分钟后，气温从 30 °C 升至 42–49 °C，90 分钟后达到 52–57 °C 的稳定水平。车前部的温度比车后部的温度高出约 3°C，面部高度的温度比膝盖高度高出约 5°C。由于 COVID-19 在 56 °C 下 30 分钟内就会灭活，我们的研究结果证实，在封闭空间内通过太阳能加热被动产生的热空气是一种很有前途的消毒策略，具有不增加成本、化学品或工作时间的优点。尽管这项技术似乎仅限于炎热的气候，但汽车制造商可能会开发出在停车期间工作的加热系统，以将该技术扩展到寒冷的气候。