in fact , indoor air pollution levels can even be higher than the outdoor levels . in addition to outdoor pollutants , secondhand tobacco smoke is one of the main sources of indoor air pollution . secondhand smoke is a mixture of exhaled mainstream smoke and sidestream smoke released from a smoldering cigarette or other smoking device ( cigar , pipe , bidi , etc . ) . scientific evidence available for more than two decades convincingly demonstrates that the exposure to secondhand smoke harms health and worsens existing health problems among non - smokers . the adverse effects of secondhand smoke are both immediate and long term , and are felt by both children and adults . in addition to several toxic chemicals and compounds , secondhand tobacco smoke also contains respirable suspended particles ( rsps ) . rsps are the proportion of total suspended particulates of a size smaller than 10 m ( pm10 ) and , among them , pm2.5 particles pose the greatest health risks because they have the ability to penetrate deeply into the lungs , where they may reach the peripheral regions of the bronchioles and interfere with gas exchange inside the lungs . monitoring the change in rsps in indoor public places is a useful tool to assess the effectiveness of smoke - free policies . globally , the who estimates that nearly 700 million or almost half of the world 's children breathe air polluted by tobacco smoke . in adults , secondhand smoke increases the risk of lung cancer by 2030% and the risk of coronary heart disease by 2530% . children are particularly vulnerable to secondhand smoke  for example , exposed children tend to get more respiratory infections , ear problems and asthma . policies requiring smoke - free environments are the most effective method of reducing shs exposure . in india , prohibition of smoking in public places is mandated under section 4 of the cigarettes and other tobacco products act ( which includes prohibition of advertisement and regulation of trade and commerce , production , supply and distribution ) of 2003 . as defined under 3(l ) of cotpa public place  means any place to which the public have access , whether as of right or not , but does not include any open space . in addition , smoking is also prohibited at the open spaces that are visited by the public , like open auditoriums , stadiums , railway stations , bus stops and other such places . the exception to this provision is that hotels with more than 30 rooms and restaurants with more than 30 seats are allowed to have a smoking area or space . airports are also an exception to this rule as they are also allowed to have a separate smoking zone . smoking area or space  is not provided at the entrance or exit of a restaurant , hotel or airport . smoking area  is used only for the purposes of smoking and no service(s ) are allowed therein . detailed rules prohibiting smoking in public places were notified on 30 may 2008 and came into force on 2 october 2008 . a study was conducted to assess the implementation of smoke - free policies and its impact on indoor air quality in the city of mumbai . mumbai ( formerly bombay ) is a large , densely populated metropolitan city ( density 22,000 inhabitants per km ) with a population of about 12 million ( census of india , 2001 ) . the venues were sampled near railway stations and commercial areas , because the concentration of venues is much higher in these areas . venues were then categorized into bars and restaurants ( hereafter called bars ) , restaurants , country liquor bars , hookah restaurants and pubs , as per signboards put up by venue owners . as per the indian context , these places are described as : 
 restaurant  premises which is carried on principally or wholly the business of supplying meals or refreshments to the public or a class of the public for consumption on the premises.bar  premises which is carried on principally or wholly the business of supplying alcoholic beverages ( beer , wine , whisky and cocktails , etc . ) and food to the public or a class of the public for consumption on the premises.country liquor bar  premises which is carried on principally or wholly the business of supplying locally made alcoholic beverages ( fenny , toddy , etc . ) to the public or a class of the public for consumption on the premises . these establishments are usually run - down and feature a clientele of mainly the working class people.pub  a pub is an entertainment venue with recorded music played by disc jockeys and there is a provision of a back bar . pubs in india may or may not have dancing floors.hookah restaurant  the hookah restaurant is an establishment where patrons share shisha ( flavored tobacco ) from a communal hookah that is placed at each table . restaurant  premises which is carried on principally or wholly the business of supplying meals or refreshments to the public or a class of the public for consumption on the premises . bar premises which is carried on principally or wholly the business of supplying alcoholic beverages ( beer , wine , whisky and cocktails , etc . ) and food to the public or a class of the public for consumption on the premises . country liquor bar  premises which is carried on principally or wholly the business of supplying locally made alcoholic beverages ( fenny , toddy , etc . ) to the public or a class of the public for consumption on the premises . these establishments are usually run - down and feature a clientele of mainly the working class people . pub a pub is an entertainment venue with recorded music played by disc jockeys and there is a provision of a back bar . hookah restaurant  the hookah restaurant is an establishment where patrons share shisha ( flavored tobacco ) from a communal hookah that is placed at each table . the sidepak uses a pump to draw air inside to measure the real - time concentration of air particles in milligrams per cubic meter . pm2.5 is a non - specific marker for shs exposure as there may be other sources of pm2.5 . the sidepak was zeroed prior to each use by attaching a high - efficiency particulate air ( hepa ) filter according to the manufacturer 's specification . air sampling was carried out any time between 6:30 pm to 11:00 pm for a minimum of 60 min at each venue . the field investigator seated himself in the central area of the venue and away from open doors , windows and kitchen entry and conducted observational monitoring , such as surveying rooms for the posting of  no smoking  signs and ash trays on tables . the monitor was placed in a central location on a table near the height at which a person breathes air . the investigators also interacted with managers , owners and waiters to assess the implementation of smoke - free policies . data recorded in the sidepak monitor at each venue were downloaded to a computer with the help of  tsi trackpro data analysis software , version 3.41 .  in accordance with the global air monitoring study protocol , a calibration factor of 0.32 , which is suitable for the contribution of secondhand tobacco smoke , was applied to all data . median and coefficient of variation of pm2.5 ( g / m ) levels were calculated separately for each venue . for describing air quality , guidelines developed by the us environmental protection agency ( epa ) were used . the air quality index ( aqi ) ranged from 0 to 500 , with a higher value indicating a greater level of air pollution and , therefore , greater health concern . mumbai ( formerly bombay ) is a large , densely populated metropolitan city ( density 22,000 inhabitants per km ) with a population of about 12 million ( census of india , 2001 ) . the venues were sampled near railway stations and commercial areas , because the concentration of venues is much higher in these areas . venues were then categorized into bars and restaurants ( hereafter called bars ) , restaurants , country liquor bars , hookah restaurants and pubs , as per signboards put up by venue owners . as per the indian context , these places are described as : 
 restaurant  premises which is carried on principally or wholly the business of supplying meals or refreshments to the public or a class of the public for consumption on the premises.bar  premises which is carried on principally or wholly the business of supplying alcoholic beverages ( beer , wine , whisky and cocktails , etc . ) and food to the public or a class of the public for consumption on the premises.country liquor bar  premises which is carried on principally or wholly the business of supplying locally made alcoholic beverages ( fenny , toddy , etc . ) to the public or a class of the public for consumption on the premises . these establishments are usually run - down and feature a clientele of mainly the working class people.pub  a pub is an entertainment venue with recorded music played by disc jockeys and there is a provision of a back bar . pubs in india may or may not have dancing floors.hookah restaurant  the hookah restaurant is an establishment where patrons share shisha ( flavored tobacco ) from a communal hookah that is placed at each table . restaurant  premises which is carried on principally or wholly the business of supplying meals or refreshments to the public or a class of the public for consumption on the premises . bar premises which is carried on principally or wholly the business of supplying alcoholic beverages ( beer , wine , whisky and cocktails , etc . ) and food to the public or a class of the public for consumption on the premises . country liquor bar  premises which is carried on principally or wholly the business of supplying locally made alcoholic beverages ( fenny , toddy , etc . ) to the public or a class of the public for consumption on the premises . these establishments are usually run - down and feature a clientele of mainly the working class people . pub a pub is an entertainment venue with recorded music played by disc jockeys and there is a provision of a back bar . hookah restaurant  the hookah restaurant is an establishment where patrons share shisha ( flavored tobacco ) from a communal hookah that is placed at each table . the sidepak uses a pump to draw air inside to measure the real - time concentration of air particles in milligrams per cubic meter . pm2.5 is a non - specific marker for shs exposure as there may be other sources of pm2.5 . the sidepak was zeroed prior to each use by attaching a high - efficiency particulate air ( hepa ) filter according to the manufacturer 's specification . air sampling was carried out any time between 6:30 pm to 11:00 pm for a minimum of 60 min at each venue . the field investigator seated himself in the central area of the venue and away from open doors , windows and kitchen entry and conducted observational monitoring , such as surveying rooms for the posting of  no smoking  signs and ash trays on tables . the monitor was placed in a central location on a table near the height at which a person breathes air . the investigators also interacted with managers , owners and waiters to assess the implementation of smoke - free policies . data recorded in the sidepak monitor at each venue were downloaded to a computer with the help of  tsi trackpro data analysis software , version 3.41 .  in accordance with the global air monitoring study protocol , a calibration factor of 0.32 , which is suitable for the contribution of secondhand tobacco smoke , was applied to all data . average concentration ( mean ) , median and coefficient of variation of pm2.5 ( g / m ) levels were calculated separately for each venue . for describing air quality , guidelines developed by the us environmental protection agency ( epa ) were used . the air quality index ( aqi ) ranged from 0 to 500 , with a higher value indicating a greater level of air pollution and , therefore , greater health concern . a total of 50 venues were selected for the study , including five restaurants , four pubs , 27 bars and restaurants , 10 country liquor bars and four hookah restaurants ( n = 50 ) . one measurement session was carried out per venue . at the time of observational monitoring of the total 50 venues , smoking within premises there was no smoking observed in all five restaurants and four pubs , while smoking was observed in seven of 27 bars . the venue with the highest proportion of smoking observed was country liquor bars ( eight out of 10 ) . in addition , the  no smoking  signage was seen at 33 venues , of which four were in marathi and two in hindi , commonly spoken languages in mumbai , while the remaining signages were in english . smoking ban ( according to owner ) vs. smoking seen ( by the investigators ) at different venues table 2 shows the respective average pm2.5 ( g / m ) concentrations in the different hospitality venues included in the study . the lowest average pm2.5 ( g / m ) level was observed in restaurants ( 55.36 g / m ) and the highest average level was observed in hookah restaurants ( 707.04 g / m ) [ figure 1 ] . the average pm2.5 level was also higher in venues where smoking was observed ( 363.04 g / m ) compared with venues where smoking was not observed ( 97.19 g / m ) [ figure 2 ] . average pm2.5 levels in different types of venues included in the study average pm2.5 ( g / m ) levels at different venues comparison of average pm2.5 ( g / m ) levels at garbage dumping grounds and non - smoking and smoking venues in the present study table 3 shows the aqi of all the venues in the study . the average pm2.5 levels at restaurants and bars were categorized as  moderate level  of health concern . country liquor bars and hookah restaurants however had average pm2.5 levels falling under the category of  hazardous level  of health concern . this study mainly focused on assessing the implementation of smoke - free policies and its impact on indoor air quality . seven months after the law mandating a ban on smoking in public places came into force , there were only 32 out of 50 venues where smoking within premises was not observed . furthermore , even though  no smoking  signages were observed in 33 of the venues , none of these venues had signage that met the mandated minimum size of 60 cm  30 cm . according to air quality guidelines of the us environmental protection agency , an aqi value for pm2.5 particles level between 0 and 50 is considered satisfactory , and air pollution at this level poses little or no health risk . in the present study , 20% of the venues fell under the  good  category [ table 3 ] . a  moderate  category ( pm2.5 particle level between 51 and 100 ) indicates that air quality is acceptable . however , for some pollutants , there may still be a moderate health concern for a small number of people . in the present study , 15 ( 30% ) venues were in this category , including nine bars , three restaurants ( average pm2.5 levels of 55.36 g / m ) and three pubs ( average 58.96 g / m ) . average pm2.5 levels of all 27 bars ( 123.79 g / m ) fell under the category of air quality was worse in 10 country liquor bars ( average 326.56 g / m ) and worst in four hookah restaurants ( average 707.04 g / m ) . the level of pollution in these venues fell under the category of  hazardous  to health ( levels between 301 and 500 ) or higher , which has the potential to trigger emergency health conditions . when these results were getting analyzed , a news about air quality at garbage dumping grounds created a lot of agitation in mumbai . the average level of pm2.5 ( g / m ) particles in the air of the dumping ground area in one area ( sudha park at ghatkopar ) was 148.5 g / mand 169.5 g / mat another area ( shivaji nagar , deonar ) . air quality at indoor public places where smoking was observed in this study was far worse than that at the garbage dumping grounds . the average level of pm2.5 ( g / m ) particles in all the venues where smoking was seen despite the ban was 363.04 g / m , which was much higher than the levels found at both the dumping grounds in mumbai [ figure 2 ] . increased levels of pm2.5 ( g / m ) in these smoking areas are also harmful to the health of the customers at these venues . the present study used a real - time aerosol monitor to measure pm2.5 levels in all venues . our exposure metric was comparable to an average concentration of pm2.5 ( g / m ) particles reported in other studies conducted in different countries . the levels we measured at smoking places ( mean pm2.5 363.04 g / m ) are broadly comparable with those reported by studies in indoor smoking public places in canada ( mean pm2.5 171 g / m ) , germany ( mean pm2.5 327 g / m ) , the united states ( mean pm2.5 265 g / m ) , the united kingdom ( mean pm2.5 285 g / m ) , malaysia ( mean pm2.5 181 g / m ) and pakistan ( mean pm2.5 169 g / m ) . a recent cross - sectional study in china reported that pm2.5 levels were much higher at bars and restaurants where smoking was observed ( 208 g / m ) than where smoking was not observed ( 99 g / m ) . the values observed in this china study were similar to those found in our study for venues where smoking was not observed ( 97.19 g / m ) , but were higher in our study for venues where smoking was observed ( 363.04 g / m ) . we also found much higher levels among country liquor bars and hookah restaurants . a study reported from ireland showed that there was a dramatic change in the air quality of bars / pubs after the national level comprehensive workplace smoke - free law was implemented in march 2004 . as a result of this law , smoking at bars / pubs in ireland went down from 98% to 5% , but remained nearly unchanged in the uk ( 9897% ) , where the law was not in effect . in our study , smoking was not observed in any of the restaurants and pubs at the time of data collection , which suggests that the 2008 ban in india has been effective in these venues . because there are no safe levels of secondhand smoke , it is important that smoke - free environment policies be as strong as possible . the objective of the smoke - free policy is to protect non - smokers from exposure to secondhand smoke , thereby enhancing the air quality of the living environment . although some people know that they are harming their self by smoking , they may not be aware of the negative effects on the people around them . many people who smoke say that restricting smoking in public would be taking away their freedom but , in reality , smoking in public takes away non - smokers right to breathe fresh air . the most serious problem with smoking in public is the negative effects it has on children . children are the future ; therefore , instead of polluting their bodies , we should be doing everything we can to keep them healthy . exposure to secondhand smoke is an entirely preventable cause of significant morbidity and mortality associated with tobacco use . smoke - free public places not only protect non - smokers from the dangers of passive smoking but also encourage smokers to quit or reduce consumption and children not to take up the habit . for smoking bans to succeed , enthusiastic endorsement by and active participation of the community and an awareness of the health consequences of exposure to secondhand smoke are needed . our study clearly demonstrated that the average pm2.5 level was highest at hospitality venues where smoking was observed compared with those where smoking was not observed , and was especially high in hookah restaurants and country liquor bars .
background : second - hand smoke contains several toxic chemicals that are known to pollute the air and harm people 's health . in india , smoking in public places has been prohibited since october 2008 as a way to reduce second - hand smoke ( shs ) exposure . 
 the purpose of the present study was to assess the implementation of smoke - free policies and its impact on indoor air quality by measuring the pm2.5 levels in bars and restaurants , restaurants , country liquor bars , hookah restaurants and pubs in mumbai.materials and methods : air quality measurements at 50 venues were conducted by using a 
 sidepak am510 personal aerosol monitor  during april to may 2009 . 
 average concentration of pm2.5 ( g / m3 ) particles was calculated separately for each venue.results:smoking was observed in 36% of the surveyed venues during an hour of data collection . 
 the pm2.5 levels ranged from 16.97 to 1101.76 g / m3 . 
 the average level of pm2.5 among non - smoking venues was 97.19 g / m3 and among smoking venues was 363.04 g / m3.conclusion : considerable scope for improvement in implementation of smoke - free policies exists . 
 the pm2.5 levels were exceedingly high in venues where smoking was observed .