Heavy dust is covering the Negev region and parts of the Jerusalem hills, resulting from storm clouds that were over Jordan during the night. Similar phenomena may appear in the Negev throughout the week, as thunderstorm clouds are expected to develop in the area. Accordingly, the Health and Environmental Protection ministries issued a warning about very high air pollution measured in the Jerusalem area, Judea, Samaria and the Jordan Valley - due to very high concentrations of respirable particles. Additionally, vulnerable populations, including heart and vascular disease patients, lung patients, the elderly, pregnant women and children, were advised to avoid strenuous physical activity outdoors, while the general population was recommended to reduce activity.