Here we’re most concerned about three types of air pollutant that cause environmental and health problems:

Particulate matter (PMs). The most dangerous tiny particles of air pollution can penetrate deep into our lungs, and can even get into the bloodstream. Particulates worsen heart and lung disease.

Nitrogen dioxide (NO2). A toxic gas that you might sometimes notice as an orange haze over a city. High levels of NO2 can cause a flare-up of asthma or symptoms such as coughing and difficulty breathing.

Ground level ozone (O3). Ground level or “bad” ozone is created by chemical reactions between oxides of nitrogen (NOx) and volatile organic compounds (VOC) in the presence of sunlight. It can irritate the eyes, nose, and throat.

Almost 300 million children around the world are exposed to toxic levels of outdoor air pollution, and those growing up in low- and middle-income countries are most at risk, according to a new report from the United Nations Children’s Fund (UNICEF). Air pollution may cause, contribute to, or aggravate respiratory disease in children, which is the most important health outcome in children. In adults, effects on the cardiovascular system are of greater importance. It is theoretically possible that air pollution exposure during childhood may pose a risk for cardiovascular disease or cancer in adulthood, however, this aspect has not yet been sufficiently studied. Childhood exposure to traffic-related air pollution is therefore of great concern and has been discussed as a key causative factor. Children are judged to be more susceptible than adults to the adverse effects of air pollution. Their developing airway and lung function distinguish them from adults and, since reduced lung growth may be seen as a permanent impairment, children may indeed be seen as a susceptible group. In addition, children cannot choose or modify their environment to the same extent as adults.

Since respiratory tract symptoms are particularly prevalent in young children, elevated risks due to exposure to traffic-related air pollution have major implications for public health. Effects of air pollution may be divided into short-term and long-term effects, depending on the time lag from exposure until they make themselves felt.

Short-term effects:

Exacerbation of asthma:

Exposure to NO2, PM10 and to some extent PM2,5 has been associated with symptoms of the lower respiratory tract in asthmatic children and with their hospital admission for asthma, often on the same or the following day

Long-term effects:

i) Sensitization to new Allergens:

Exposure to NO2 (or NOx) has been shown, in some studies, to be associated with sensitization to common new allergens in children leading to future recurrent episodes of asthma exacerbations. In addition, the health effects of air pollution may be especially pronounced in individuals who are genetically susceptible, as well as in those exposed to other environmental factors. However, the association between air pollution and sensitization needs to be studied further before it can serve as the basis for preventive action.

ii) Stunted lung development:

There is strong evidence that exposure to traffic-related air pollution in childhood adversely affects children’s age-dependent development in lung function, at least up to adolescence, an effect that probably — although this remains to be studied — persists into adulthood, thus exerting an impact on adult respiratory health as well. Children are judged to be more susceptible than adults to the adverse effects of air pollution. Their developing airway and lung function distinguishes them from adults and, since reduced lung growth may be seen as a permanent impairment, children may indeed be seen as a susceptible group. Whether they are especially susceptible when it comes to other respiratory effects is less clear. In addition, children cannot choose or modify their environment to the same extent as adults.

What you can do: In case you think air pollution is extremely high in the area you live in, you can restrict the time your child spends outdoors. If your child complains of sore eyes, cough, or sore throat, you should immediately prevent her from playing outdoors.