# Air Pollution Associates with Cancer Incidences in Poland
## 1 Introduction  
Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. Humans are affected by over 100 types of cancers. Exposure to ionizing radiation and air pollution are listed among other carcinogenic factors. Air pollutants include oxides of sulfur, nitrogen and carbon, as well as benzene and smog-forming particles, namely PM2.5(in which PM stands for particulate matter)--atmospheric aerosols (suspended dust) with a diameter of no more than 2.5 \(\upmu\)m, which according to the World Health Organization are the most harmful to human health from other atmospheric pollutants, and PM10--a mixture of suspended particles with a diameter of no more than 10 \(\upmu\)m. The composition may additionally include such toxic substances as, for example, benzopyrene, dioxins, and furans. Air pollution occurs when harmful or excessive quantities of substances, including gases, particulates, and biological molecules, are introduced into the Earth's atmosphere. It may cause diseases, allergies and even death in the most severe cases [1]. For many years, studies have been conducted to examine the impact of air pollution on the risk and incidence of cancer. Canadian researchers investigated the impact of sulfur dioxide (SO\({}_{2}\)) air pollution on mortality in breast and colon cancer patients in 20 cities in their country. It was assumed that SO\({}_{2}\) absorbs ultraviolet light in the region of the spectrum which is most active in forming vitamin D in the skin. Since vitamin D plays a role in reducing the risk of colon and breast cancer, high concentrations of the pollutant (acid haze) may lead to its deficiencies in exposed populations [2]. Indeed, statistically significant positive associations were found between air pollution and age-adjusted mortality rates for colon cancer in women and men, and breast cancer in women. Researchers from Spain (Barcelona Institute of Global Health) and the United States (American Cancer Society) carried out a large-scale epidemiological study that linked certain air pollutants to kidney, bladder, and colon diseases. The study involved over 600,000 adults in the US who were followed up for 22 years (from 1982 to 2004). A team of researchers investigated a possible association of deaths from cancer in 29 places in the country with a long-term population exposure to three types of pollutants: PM2.5, nitrogen dioxide (NO\({}_{2}\)), and ozone (O\({}_{3}\)). Research has shown that PM2.5 was associated with mortality from kidney and bladder cancer, and exposure to NO\({}_{2}\) was associated with colorectal cancer death [3]. In 2009, the results of the long-term studies on geographical variation in cancer mortality rates were reported. Researchers from the Nutrition and Health Research Center, located in the United States, proved that there is a connection between atmospheric air pollution from fossil fuel combustion with the risk of cancer development in the digestive tract, elimination organs (esophageal and bladder), and female reproductive organs [4]. Studies carried out at the National Statistics Institute in Spain have allowed for the designation of industries that contribute to the emission of the most dangerous compounds into the atmosphere. These include mining, paper and wood production plants, the food industry, metal production and processing, and ceramics. Further studies were then conducted to verify whether the proximity of such industries that emit pollutants into the air could be an added risk factor for colorectal cancer mortality [5]. A summary of the past literature (only relevant studies) is presented in Table 1.  
Poland belongs to the top European Union countries when it comes to air pollution. The very poor air quality that the inhabitants of many regions of Poland inhale should be viewed not only in terms of environmental degradation, but also as a huge example of neglected development for the country.