Air pollution refers to the presence of certain gases as well as solid and liquid particles called aerosols, that are harmful to health and the environment. Most air pollutants are caused by burning fossil fuels – in power plants, refineries, industry and transportation. Natural air pollution sources (accounting for a small fraction) include dust, pollen, mold and wildfires.
Air pollution in Israel claims over 2,500 lives annually. Israel’s Ministry of Environment assesses pollution costs (in health-related and other damages) at a staggering NIS 31 billion annually.
Air pollution is generally defined using two primary standards:
1) Target Health Values, based on international standards – such as those set by the World Health Organization. These values are not necessarily feasible in Israel and therefore not mandatory.
2) Environmental Standards – currently feasible in Israel and therefore mandatory. Values exceeding these levels violate the law.
Israel’s Clean Air Law sets the following standards for key pollutants:
Benzene, a known carcinogen, is a colorless, flammable liquid with a sweet odor. It belongs to a group of compounds known as hydrocarbons – naturally-occurring compounds that form the basis of crude oil, natural gas, coal and other petroleum products. The International Agency for Research on Cancer (IARC) has determined that benzene causes leukemia in humans. According to the WHO and Israel’s Almog Committee, appointed by the Ministry of Environment, benzene is a carcinogen at any level, even below its assigned environmental values. Additionally, benzene and other hydrocarbon compounds, including toluene and xylene, can harm the central nervous system at very high concentrations, leading to death.
Source: Most benzene exposure results from human activities. It occurs naturally in crude oil, gasoline and cigarette smoke (though also in volcanoes, forest fires and other natural processes). Benzene is among the 20 most widely used chemicals in the U.S, applied to produce other chemicals, such as plastics, lubricants, rubbers, pesticides, and even dyes, detergents and drugs.
Benzene Target Health Values: Due to its toxicity, the WHO has not defined a threshold value below which there is no health hazard due to benzene exposure.
Benzene Environmental Health Standard: In Israel, the daily environmental standard is set to 1.2 parts per billion (PPB), meaning that values above this level violate the law. Note that this does not refer to a single value of 1.2 PPB but rather a daily average (of 288 samples measured every 5 minutes).
Particulate Matter: PM10, PM2.5
Particulate matter (PM) stands for mixtures of tiny solid or liquid droplets in the air containing hundreds of different materials, such as metals, black carbon, ammonia, sulfates, nitrates, and soil particles. The particles vary greatly in size and shape. While the naked eye can see some particles, such as dust, dirt, soot, and smoke, others, such as PM10 and PM2.5, are so small we can only detect them with a microscope. (For perspective, the average human hair is roughly 70 micrometers.)
Source: Particulate matter is primarily created by the complex reactions of sulfur dioxide, nitrogen oxides and other pollutants emitted by transportation, power plants and industries.
Health effects: PM2.5 poses the most significant health risk of the varying forms of particulate matter. The smaller the particle, the deeper it penetrates the respiratory system, passes into the bloodstream, and can even reach the brain. Smaller particles may also adsorb carcinogenic compounds.
According to the World Health Organization, there is no safe threshold for respiratory exposure to small particles. Numerous studies link PM pollution to:
- Premature death in people with heart or lung disease
- Nonfatal heart attacks
- Irregular heartbeat
- Aggravated asthma
- Decreased lung function
- Respiratory symptoms (including airway irritation, coughing, or difficulty breathing).
- Liver damage
Environmental Effects: Fine particles can be carried over long distances by the wind to settle down on the ground or water, acidifying lakes and streams, depleting soil nutrients, damaging forests, crops, etc.
PM10 Environmental Standards: The WHO PM10 standard is 50 mcg/m3 per day and 20 mcg/m3 per year. Israel’s Clean Air Act allows for up to 130 mcg/m3 per day and 50 per year.
PM2.5 Environmental Standards: The WHO PM 2.5 standard is 25 mcg/m3 per day and ten mcg/m3 per year. Israel’s Clean Air Act allows 37.5 mcg/m3 per day and 25 mcg/m3 per year.
NOx (Nitrogen Oxides)
Nitrogen oxides are a group of highly reactive gaseous air pollutants consisting mainly of two gases: a colorless gas known as nitrogen monoxide (NO) and nitrogen dioxide (NO2), a brown-orange gas. Nitrogen oxides produce the yellowish/brown color of smog. While all nitrogen oxides are harmful to human health and the environment, NO2 is of greatest concern and is used as the indicator for all nitrogen oxides.
Source: Natural sources include volcanos and bacteria, but nitrogen oxides mainly originate from processes involving the burning of fossil fuels, such as those occurring in transportation, power plants, and factories.
Health effects: Short-term high NO2 concentrations can aggravate existing respiratory diseases, irritating airways and causing coughing, wheezing, or labored breathing. More prolonged exposure may damage lung tissue and airways, leading to asthma, respiratory inflammation and increased susceptibility to viral diseases. Studies have correlated high nitrogen dioxide concentrations with increased asthma attacks and emergency hospital visits. In pregnant women – elevated NO2 levels are linked to an increased risk of gestational diabetes and preeclampsia, fetal heart defects (from exposure during the first trimester) and low birth weight (last-trimester exposure). Studies have also correlated high NO2 levels with Sudden Infant Death Syndrome (SIDS). Moreover, nitrogen oxides also react with other chemicals in the air to form ozone and particulate matter, harming the respiratory system.
NO2 Environmental Standards: About 200 micrograms per cubic meter per hour (mcg/m3h) and 40 mcg/m3 per year.
Sulfur dioxide is a toxic gas responsible for the smell of burnt matches.
Source: Though released naturally by volcanic activity, sulfur dioxide is mainly a byproduct of copper extraction and the burning of fossil fuels in transportation and industry. High SO2 concentrations can also lead to the formation of other sulfur oxides (SOx), which can react with yet additional compounds to form particulate matter, another key air pollutant.
Health effects: Short-term exposure to SO2 can harm the respiratory system and impair breathing. Asthmatics and patients with chronic lung disease (COPD and bronchitis) are particularly vulnerable.
SO2 Target Health Values: Israel’s clean air standard for SO2 (below which no apparent negative health effects are known) is 500 micrograms per cubic meter (mcg/m3) for ten minutes and 20 mcg/m3 per day.
SO2 Environmental standards: (Above which violates the law): 50 mcg/m3 per day and 20 mcg/m3 per year.
O3 (Ozone) - Good or Bad for Us, Depending on Location
Ozone is a gas consisting of three oxygen atoms. It occurs in Earth’s upper atmosphere (called stratospheric ozone) and ground level.
Stratospheric ozone is critical to life on Earth because it forms a protective layer that shields us from the sun’s ultraviolet rays. In contrast, ground-level ozone is a harmful air pollutant and the main ingredient in smog. It forms when pollutants such as nitrogen oxides and volatile organic compounds (emitted by cars, power plants and other sources) react chemically in sunlight. Therefore, this pollutant is most likely to reach unhealthy levels on hot sunny days in urban environments. However, it can also be carried long distances by the wind, impacting rural areas.
Health effects: Ozone can be harmful, especially at the high levels formed during hot, sunny days. Asthmatics, children (whose lungs are still developing and generally spend more time outdoors), and senior citizens (most likely to suffer from cardiopulmonary diseases) are at the greatest risk from ozone exposure. However, short-term exposure can impact everyone, causing irritation to the eyes and nose and impairing lung function. Studies have correlated higher ozone concentrations with increased asthma attacks, emergency hospital visits and even respiratory and cardiac disease mortality among sensitive populations.
Ozone Target Health Values: (below which there are no likely adverse health effects) is 100 mcg/m3.
Ozone Environmental Standards: The recommended WHO level is 100 mcg/m3 for eight hours. Israel’s standard is set at 140 mcg/m3 for eight hours due to the region’s strong solar radiation, which increases ozone production.