Pollutants include lead, sulfur dioxide, heavy metals and other air pollutants. Modern pollution prevention technologies are capable of addressing all of these potential pollutants. Algae can filter high levels of toxins and pollutants. Burning generates both airborne pollutants and ash rich in toxic materials, mainly heavy metal compounds. Sewage also contains environmental persistent pharmaceutical pollutants. Particulate matter is the most harmful to public health of all air pollutants in Europe. The administration loosened regulations on toxic pollutants, such as mercury. Other factors include certain infections, exposure to ionizing radiation and environmental pollutants. This process is very vulnerable to multiple toxic substances, environmental pollutants, and nutritional imbalance. For others, its through inhaling (e.g. air pollutants) or ingesting it (e.g. toxic metals). The NESHAPs were incorporated into a greatly expanded program for controlling toxic air pollutants. These substances are consequently known as "persistent organic pollutants" or POPs. They are likely involved in detoxification or biodegradation of many other environmental pollutants. Risk factors include exposure to tobacco smoke, dust, and other air pollutants. Seagrasses also enhance water quality by stabilizing heavy metals, pollutants, and excess nutrients.