**3.1 Indoor air pollution**

There are many sources of indoor air pollution, which can be increase with outdoor pollutions contaminant. Exposure to indoor air pollutants can cause detrimental health issues, which could cause minor symptoms such as allergies represented with constant sneezing, coughing which can be exacerbated with indoor change in temperatures and irritants [17]. This irritant could cause only upper respiratory symptoms; however, it could get complicated with lower respiratory symptoms such as reactive airway disease and bronchial asthma exacerbations in patients with underlying hyperactive airways. It's important to note that indoor environments will get outdoor mixtures of pollutants in which will reaccumulate with indoor sources causing a conjoined effect. Indoor factors could range from animal matters, molds from humid areas, secondhand tobacco exposure and dust mites among others that will be further discuss.

### **3.2 Particulate matter**

It consists of particles suspended in the air which can be from human sources such as factories, vehicles, personal or community transports, electricity plants and industrial fumes, or natural matters such as pollen, spontaneous fires, spores, animal debris and

*Environmental and Occupational Factors; Contribution and Perspectives on Difficult to Treat… DOI: http://dx.doi.org/10.5772/intechopen.108605*

plants among others. It's important to note that particulate matter can be divided with sizes going from particles less than 10 um in diameter (PM10) to particles less than 2.5 um (PM2.5) [18]. One of the strongest clinical differences between this particle is that particles less than 10 um could enter the respiratory system, and the smallest ones will be able to enter the alveoli which is the distal component of the airway. Particles that are between 2.5 um to 10 um will not be able to reach the alveoli but will be possible to deposit in the more proximal airways in which the clinical sequela will be different. With this it's important to point out that proximal airway deposition will have a clinical presentation of asthma, with reactive airway disease, which may cause inflammation and subsequent exacerbation of underlying asthma. Multiple studies have shown that strong particulate exposure led to lower pulmonary function and deterioration overtime [19]. Physiology of particulate matter starts when it enters the body through the nose and mouth when we are breathing, at that moment the body will be able to eliminate most of the largest particles which are the ones more than 2.5 um, but the other smaller particles will continue passage into the lungs and have detrimental stationary inflammatory effects in the alveoli. This effect could lead to interstitial lung disease with permanent parenchyma damage as well acute diseases such as hypersensitivity pneumonitis, chronic bronchitis among others [20]. It will not only lead to respiratory symptoms if can case cardiovascular complications such as arrhythmia and coronary artery disease. This makes particulate matter a detrimental environmental factor to the healthy people but most importantly to patients with comorbidities such as asthma.

### **3.3 Indoor nitrogen dioxide**

Nitrogen dioxide is an irritant gas that has strongly been linked with respiratory symptoms with negative long term sequelas. It's a product of elevated temperature combustion as can been seen in indoor gasses such as indoor stoves. There are other sources of NO2 such as power plants which is specifically important in low-income countries with poor power supply, as well diesel power construction machines and industrial machines. It's important to note that even though most of the NO2 sources are from the outdoors, this outdoors contaminants could penetrate inside houses and became constant irritants to the households, making patients with pulmonary diseases more vulnerable [21]. Severe health effects of NO2 exposures would affect proximal airway causing worsened of cough with wheezes, causing increased in asthma exacerbations, leading to more hospital admissions. Constant exposure will eventually cause increased airway inflammation with remodeling of the airway, making it more severe with time. This patient will be escalating asthma treatments quickly without major relief and eventually will ne on advanced asthma treatments of this exposures are not recognized. There are multiple scientific studies that link decreased in pulmonary function such as diminished peak flows with higher exposure of N02. Avoidance and early recognition of improperly used heating devices and combustion devices is of greatest importance for avoidance [22]. Special attention to poorly vented placed, in which combustion products are been produced such as Nitrogen dioxide (NO2), carbon monoxide, Sulfur dioxide (SO2) and particulate matter as previously mentioned is key on the management of this patients.

#### **3.4 Dust mites**

Dust Mites are a worldwide problem in respiratory vulnerable patients. This are tiny organism that live in furniture's such as beddings, bed, soft toys, and clothing

most of the time at people's homes. This organism is not airborne they live in soft and humid environments [23]. Dust mites most of the time become airborne with cleaning activities such as vacuum and dusting which organism will be mobilized and as other particulate matter react to nasal receptors and start the perpetuating sequela. Dust mite allergies can be detected with blood samples, for better preventive measures which the goal when recognizing exacerbating factors. Other preventive measures that will be discussed is the use of allergen proof mattress with pillowcases, close washing of bedding in a weakly basis, carpets and rugs management with high efficiency particulate air filter. The physiology of symptoms starts with indoor mites that are constantly feeding from death skin, that eventually will liberate allergens during that chemical process that will eventually lead to an asthma trigger, that most of the time will start with upper airway symptoms, with eventual bronchospasm due to airway hyperresponsiveness. It's important to recognize Dust mites because it's a strong allergen, difficult to take care of, and take meticulous weekly indoor management protocols for prevention of exacerbations. Asthma medications can help ameliorate dust mite reaction, but preventive measures with bedding cleaning, keeping beds with dust proof covers as well warm cleaning with higher degree temperature is the recommended range for adequate cleaning [24].
